Microgravity

A Teacher’s Guide With Activities

in Science, Mathematics, and Technology

National Aeronautics and Space Administration

Office of Life and Microgravity Sciences and Applications

Microgravity Research Division

Office of Human Resources and Education

Education Division

This publication is in the Public Domain and is not protected by copyright.

Permission is not required for duplication.

EG-1997-08-110-HQ
Acknowledgements This publication was developed for the National

Aeronautics and Space Administration with the

assistance of the many educators of the

Aerospace Education Services Program,

Oklahoma State University.

Writers:

Melissa J. B. Rogers, MS

TAL-CUT Company

NASA Lewis Research Center

Cleveland, OH

Gregory L. Vogt, Ed-D.

Teaching From Space Program

NASA Johnson Space Center

Houston, TX

Michael J. Wargo, Sc.D.

Microgravity Research Division

NASA Headquarters

Washington, DC
Activity Contributors

Microgravity In The Classroom

Accelerometers

Around The World

Inertial Balance

Candle Drop

Crystallization Model

Gregory L. Vogt, Ed.D.

Teaching From Space Program

NASA Johnson Space Center

Gravity-Driven Fluid Flow

Charles E. Bugg, Ph.D. Professor Emeritus

University of Alabama, Birmingham

and

Chairman and Chief Executive Officer

Biocrypt Pharmaceuticals, Inc.

Craig D. Smith, Ph.D.

Manager

X-Ray Crystallography Laboratory

Center for Macromolecular

Crystallography

University of Alabama at Birmingham

Surface Tension-Driven Flows

Gregory L. Vogt, Ed.D.

Teaching From Space Program

NASA Johnson Space Center

R. Glynn Holt, Ph.D.

Research Assistant Professor

Boston University

Aeronautics and Mechanical Engineering

Department

Temperature Effects on Surface

Tension

Michael F. Schatz

School of Physics

Georgia Institute of Technology

Stephen J. VanHook

Center for Nonlinear Dynamics

Department of Physics

University of Texas at Austin

Candle Flames

Howard D. Ross, Ph.D.

Chief

Microgravity Combustion Branch

NASA Lewis Research Center

Crystal Growth and Buoyancy-Driven

Convection Currents

Roger L. Kroes, Ph.D.

Researcher

Microgravity Science Division

NASA Marshall Space Flight Center

Donald A. Reiss, Ph.D.

Researcher

Microgravity Science Division

NASA Marshall Space Flight Center

Rapid Crystallization

Microscopic Observation of Crystals

David Mathiesen, Ph.D.

Assistant Professor

Case Western Reserve University

and

Alternate Payload Specialist

USML-2 Mission

Zeolite Crystal Growth

Albert Sacco, Jr.

Head

Department of Chemical Engineering

Worchester Polytechnical Institute

and

Payload Specialist

USML-2 Mission
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏) i

As opportunities for extended space flight have

become available, microgravity research in

physical and biological sciences has grown in

importance. Using the Space Shuttle and soon the

International Space Station, scientists are able to

add long term control of gravity’s effects to the

short list of variables they are to manipulate in

their experiments. Although most people are

aware of the floating effects of astronauts and

things in orbiting spacecraft, few understand what

causes microgravity much less how it can be

utilized for research.

The purpose of this curriculum supplement guide

is to define and explain microgravity and show

how microgravity can help us learn about the

phenomena of our world. The front section of the

guide is designed to provide teachers of science,

mathematics, and technology at many levels with

a foundation in microgravity science and

applications. It begins with background

information for the teacher on what microgravity

is and how it is created. This is followed with

information on the domains of microgravity

science research; biotechnology, combustion

science, fluid physics, fundamental physics,

materials science, and microgravity research

geared toward exploration. The background

section concludes with a history of microgravity

research and the expectations microgravity

scientists have for research on the International

Space Station.

Following the background information are

classroom activities that enable students to

experiment with the forces and processes

microgravity scientists are investigating today.

The activities employ simple and inexpensive

materials and apparatus that are widely available

in schools. The activities emphasize hands-on

involvement, prediction, data collection and

interpretation, teamwork, and problem solving.

Activity features include objectives, materials and

tools lists, management suggestions, assessment

ideas, extensions, instructions and illustrations,

student work sheets, and student readers.

Because many of the activities and

demonstrations apply to more than one subject

area, a matrix chart relates activities to national

standards in science and mathematics and to

science process skills.

Finally, the guide concludes with a suggested

reading list, NASA educational resources

including electronic resources, and an evaluation

questionnaire. We would appreciate your

assistance in improving this guide in future

editions by completing the questionnaire and

making suggestions for changes and additions.

The evaluation can be sent to us by mail or

electronically submitted through the Internet site

listed on the form.

How To Use This Guide
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏) ii

Note on Measurement and

Format

In developing this guide, metric units of

measurement were employed. In a few

exceptions, notably within the “Materials and

Tools” lists, British units have been listed. In the

United States, metric-sized parts such as screws

and wood stock are not as accessible as their

British equivalents. Therefore, British units have

been used to facilitate obtaining required

materials.

The main text of this guide uses large print

located in a wide column. Subjects relating to

mathematics, physical science, and technology

are highlighted in bold. Definitions, questions for

discussion, and examples are provided in smaller

print in the narrow column of each page. Each

area highlighted in the text has a corresponding

section in the narrow column. This corresponding

section first lists applicable Mathematics and

Science Content Standards, indicated by grade

level: ∆ Grades 5–8, ❏ Grades 9-12. We have

attempted to position the appropriate discussion

as close as possible to the relevant highlighted

text. A key word or phrase in each margin

discussion is also highlighted for ease in

identifying related text.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏) iii

Table of Contents

Introduction

First, What is Gravity? ............................................................................................... 1

What is Microgravity? ................................................................................................ 1

Creating Microgravity ................................................................................................ 3

Drop Facilities ..................................................................................................... 7

Aircraft ................................................................................................................ 8

Rockets............................................................................................................... 9

Orbiting Spacecraft ........................................................................................... 10

Microgravity Science Primer .......................................................................................... 13

The Microgravity Environment of Orbiting Spacecraft ............................................. 15

Biotechnology .......................................................................................................... 16

Protein Crystal Growth ..................................................................................... 18

Mammalian Cell and Tissue Culture ................................................................ 19

Fundamental Biotechnology ............................................................................ 21

Combustion Science ............................................................................................... 21

Premixed Gas Flames ..................................................................................... 25

Gaseous Diffusion Flames ............................................................................... 25

Liquid Fuel Droplets and Sprays ...................................................................... 25

Fuel Particles and Dust Clouds........................................................................ 26

Flame Spread Along Surfaces ......................................................................... 26

Smoldering Combustion................................................................................... 27

Combustion Synthesis ..................................................................................... 27

Fluid Physics ........................................................................................................... 28

Complex Fluids ................................................................................................ 29

Multiphase Flow and Heat Transfer ................................................................. 31

Interfacial Phenomena ..................................................................................... 32

Dynamics and Stability..................................................................................... 33

Fundamental Physics .............................................................................................. 34

Materials Science .................................................................................................... 37

Electronic Materials.......................................................................................... 39

Glasses and Ceramics ..................................................................................... 40

Metals and Alloys ............................................................................................. 41

Polymers .......................................................................................................... 43

Microgravity Research and Exploration................................................................... 44
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏) iv

Microgravity Science Space Flights ...............................................................................46

International Microgravity Laboratory-1, January 1992 .......................................49

United States Microgravity Laboratory-1, June 1992 ..........................................49

Spacelab-J, September 1992 ..............................................................................51

United States Microgravity Payload-1, October 1992 .........................................52

United States Microgravity Payload-2, March 1994 ............................................53

International Microgravity Laboratory-2, July 1994 .............................................55

United States Microgravity Laboratory-2, October 1995 .....................................57

United States Microgravity Payload-3, February 1996 ........................................59

Life and Microgravity Spacelab, June 1996 ........................................................62

Shuffle/Mir Science Program, March 1995 to May 1998 .....................................64

Future Directions ............................................................................................................68

Glossary .........................................................................................................................71

Activities .........................................................................................................................75

NASA Resources for Educators ...................................................................................167

NASA Educational Materials ........................................................................................168
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

1

Introduction

Space flight is important for rnany reasons. Space

flight carries scientific instruments and human

researchers high above the ground, permitting us

to see Earth as a planet and to study the complex

interactions of atmosphere, oceans, land, energy,

and living things. Space flight lifts scientific

instruments above the filtering effects of the

atmosphere, making the entire electromagnetic

spectrum available and allowing us to see more

clearly the distant planets, stars, and galaxies.

Space flight permits us to travel directly to other

worlds to see them close up and sample their

compositions. Finally, space flight allows

scientists to investigate the fundamental states of

matter—solids, liquids, and gases—and the

forces that affect them in a microgravity

environment.

The study of the states of matter and their

interactions in microgravity is an exciting

opportunity to expand the frontiers of science.

Areas of invest’gation include biotechnology,

combustion scie,lce, fluid physics, fundamental

physics, materials science, and ways in which

these areas of research can be used to advance

efforts to explore the Moon and Mars.

Microgravity is the subject of this teacher’s guide.

This publication identifies the underlying

mathematics, physics, and technology principles

that apply to microgravity. Supplementary

information is included in other NASA educational

products.

First, What is Gravity?

Gravitational attraction is a fundamental property

of matter that exists throughout the known

universe. Physicists identify gravity as one of the

four types of forces in the universe. The others

are the strong and weak nuclear forces and the

electromagnetic force.

Mathematics Standards

❏ Mathematical Connections

❏ Mathematics as Communication

∆ Number and Number Relationships

∆ Number Systems and Number Theory

Science Standards

∆ ❏ Physical Science

∆ ❏ Unifying Concepts and Processes

The electromagnetic spectrum is generally separated into

different radiation categories defined by frequency (units of

Hertz) or wavelength (units of meters). Wavelength is commonly

represented hy the symbol λ.

Example:

Name

Xrays

Ultraviolet

Visible Light

Infrared

Microwave

Television

AM Radio

Mathematics Standards

∆ ❏ Algebra

❏ Conceptual Underpinnings of Calculus

Geometry

❏ Geometry from an Algebraic Perspective

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Reasoning

❏ Trigonometry

Science Standards

∆ ❏ Physical Science

∆ ❏ Unifying Concepts and Processes

An impressed force is an action exerted upon a body,

in order to change its state, either of rest, or of uniApproximate

Wavelength (m)

= 10-15 to 10-9

= 10-8 to 10-7

= 10-7 to 10-6

= 10-6 to 10-3

= 10-3 to 10-1

= 10-1 to 1

= 10-2 to 103
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

2

form motion in a straight line. A body force acts on the entire

mass as a result of an external effect not due to direct contact;

gravity is a body force. A surface force is a contact force that acts

across an internal or external surface of a body.

Mathematics Standards

∆ ❏ Algebra

❏ Conceptual Underpinnings of Calculus

∆ Geometry

❏ Geometry from an Algebraic Perspective

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Reasoning

❏ Trigonometry

Science Standards

∆ ❏ Physical Science

∆ ❏ Unifying Concepts and Processes

Velocity is the rate at which the position of an object changes

with time; it is a vector quantity. Speed is the magnitude of

velocity.

Mathematics Standards

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Reasoning

Science Standards

∆ ❏ History and Nature of Science

∆ ❏ Science as Inquiry

∆ ❏ Unifying Concepts and Processes

Newton’s discovery of the universal nature of the force of

gravity was remarkable. To take the familiar force that makes an

apple fall to Earth and be able to recognize it as the same force

that keeps the planets on their quiet and predictable paths

represents one of the major achievements of human intellectual

endeavor. This ability to see beyond the obvious and familiar is

the mark of a true visionary. Sir Issac Newton’s pioneering work

epitomizes this quality.

Mathematics Standards

∆ ❏ Algebra

∆ Computation and Estimation

❏ Functions

∆ ❏ Mathematical as Communication

∆ Number and Number Relationships

∆ Patterns and Functions

Science Standards

∆ ❏ Unifying Concepts and Processes

More than 300 years ago the great English

scientist Sir Isaac Newton published the

important generalization that mathematically

describes this universal force of gravity. Newton

was the first to realize that gravity extends well

beyond the domain of Earth. The basis of this

realization stems from the first of three laws he

formulated to describe the motion of objects. Part

of Newton’s first law, the law of inertia, states that

obiects in motion travel in a straight line at a

constant velocity unless acted upon by a net

force. According to this law, the planets in space

should travel in straight lines. However, as early

as the time of Aristotle, scholars knew that the

planets travelled on curved paths. Newton

reasoned that the closed orbits of the planets are

the result of a net force acting upon each of them.

That force, he concluded, is the same force that

causes an apple to fall to the ground—gravity.

Newton’s experimental research into the force of

gravity resulted in his elegant mathematical

statement that is known today as the Law of

Universal Gravitation. According to Newton, every

mass in the universe attracts every other mass.

The attractive force between any two objects is

directly proportional to the product of the two

masses being considered and inversely

proportional to the square of the distance

separating them. If we let F represent this force, r

represent the distance between the centers of the

masses, and m1 and m2 represent the magnitudes

of the masses, the relationship stated can be

written symbolically as:

From this relationship, we can see that the greater

the masses of the attracting objects, the greater

the force of attraction between them. We can also

see that the farther apart the objects are from

each other, the less the attraction. If the distance

between the objects doubles, the attraction

between them diminishes by a factor of four, and

if the distance triples, the attraction is only oneninth as much.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

3

The eighteenth-century English physicist Henry

Cavendish later quantified Newton’s Law of

Universal Gravitation. He actually measured the

gravitational force between two one kilogram

masses separated by a distance of one meter.

This attraction was an extremely weak force, but

its determination permitted the proportional

relationship of Newton’s law to be converted into

an equality. This measurement yielded the

universal gravitational constant, G. Cavendish

determined that the value of G is 6.67 x 10-11 N

m2/kg2. With G added to make the equation, the

Law of Universal Gravitation becomes:

What is Microgravity?

The presence of Earth creates a gravitational field

that acts to attract objects with a force inversely

proportional to the square of the distance

between the center of the object and the center of

Earth. When we measure the acceleration of an

object acted upon only by Earth’s gravity at the

Earth’s surface, we commonly refer to it as one g

or one Earth gravity. This acceleration is

approximately 9.8 meters per second squared (m/

s2). The mass of an object describes how much

the object accelerates under a given force. The

weight of an object is the gravitational force

exerted on it by Earth. In British units (commonly

used in the United States), force is given in units

of pounds. The British unit of mass

corresponding to one pound force is the slug.

While the mass of an object is constant and the

weight of an object is constant (ignoring

differences in g at different locations on the

Earth’s surface), the environment of an object

may be changed in such a way that its apparent

weight changes. Imagine standing on a scale in a

stationary elevator car. Any vertical accelerations

of the elevator are considered to be positive

indicates proportionality

indicates equality

is an expression

is an equation

Mathematics Standards

∆ ❏ Algebra

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Communication

∆ Measurement

Science Standards

∆ ❏ Science and Technology

∆ ❏ Science as Inquiry

∆ ❏ Unifying Concepts and Processes

The internationally recognized Systeme International (Sl) is a

system of measurement units. The Sl units for length (meter) and

mass (kg) are taken from the metric system. Many dictionaries

and mathematics and science textbooks provide conversion tables

between the metric system and other systems of measurement.

Units conversion is very important in all areas of life. for

example in currency exchange, airplane navigation, and scientific

research.

Units Conversion Examples

1 kg ≅ 2.2lb 1 in = 2.54cm

1 liter ≅ 1 qt 1 yd ≅ 0.9 m

Questions for Discussion

• What common objects have a mass of about 1 kg?

• What are the dimensions of this sheet of paper in cm and

inches?

• How many liters are there in a gallon?

Mathematics Standards

∆ Computation and Estimation

∆ ❏ Mathematics as Communication

∆ Number and Number Relationships

∆ Number Systems and Number Theory
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

4

Science Standards

∆ ❏ Science as Inquiry

∆ ❏ Science in Personal and Social Perspectives

∆ ❏ Unifying Concepts and Processes

Scientific notation makes it easier to read, write, and manipulate

numbers with many digits. This is especially useful tor making

quick estimates and for indicating the number of significant

figures.

Examples:

0.001 = 10-3

 10 = 101

1000 = 103

Which is bigger, 6 x 10-3 or 8 x 10-4? 6 x 103 or 8 x 104?

How much bigger?

Mathematics Standards

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Reasoning

Science Standards

∆ ❏ Science and Technology

∆ ❏ Science as Inquiry

∆ ❏ Unifying Concepts and Processes

Questions for Discussion

• How does a scale work ?

• What does a scale measure?

• How many different kinds of scales can you list?

• Do they need gravity for them to work?

• Would you get different results on the Moon or Mars?

• How can you measure the mass of an object in

microgravity?

upwards. Your weight, W, is determined by your

mass and the acceleration due to gravity at your

location.

If you begin a ride to the top floor of a building,

an additional force comes into play due to the

acceleration of the elevator. The force that the

floor exerts on you is your apparent weight, P, the

magnitude of which the scale will register. The

total force acting on you is F=W+P=mae

, where ae

is the acceleration of you and the elevator and

W=mg. Two example calculations of apparent

weight are given in the margin of the next page.

Note that if the elevator is not accelerating then

the magnitudes W and P are equal but the

direction in which those forces act are opposite

(W=-P). Remember that the sign (positive or

negative) associated with a vector quantity, such

as force, is an indication of the direction in which

the vector acts or points, with respect to a defined

frame of reference. For the reference frame

defined above, your weight in the example in the

margin is negative because it is the result of an

acceleration (gravity) directed downwards

(towards Earth).

Imagine now riding in the elevator to the top floor

of a very tall building. At the top, the cables

supporting the car break, causing the car and.

you to fall towards the ground. In this example,

we discount the effects of air friction and elevator

safety mechanisms on the falling car. Your

apparent weight P=m(ae

-g)=(60 kg)(-9.8 m/s2-

(-9.8 m/s2)) = O kg m/s2; you are weightless. The

elevator car, the scale, and you would all be

accelerating downward at the same rate, which is

due to gravity alone. If you lifted your feet off the

elevator floor, you would float inside the car. This

is the same experiment that Galileo is purported

to have performed at Pisa, Italy, when he dropped

a cannonball and a musketball of different mass

at the same time from the same height. Both balls

hit the ground at the same time, just as the

elevator car, the scale, and you would reach the

ground at the same time.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

5

Normal

weight

Heavier

than normal

Lighter

than normal

No apparent

weight

Acceleration and weight

The person in the stationary elevator car experiences normal

weight. In the car immediately to the right, apparent weight

increases slightly because of the upward acceleration.

Apparent weight decreases slightly in the next car because of

the downward acceleration. No weight is measured in the last

car on the right because of free fall.

For reasons that are discussed later, there are

many advantages to performing scientific

experiments under conditions where the apparent

weight of the experiment system is reduced. The

name given to such a research environment is

microgravity. The prefix micro- (m) derives from

the original Greek mikros meaning small. By this

definition, a microgravity environment is one in

which the apparent weight of a system is small

compared to its actual weight due to gravity. As

we describe how microgravity envifonments can

be produced, bear in mind that many factors

contribute to the experienced accelerations and

that the quality of the microgravity environment

depends on the mechanism used to create it. In

practice, the microgravity environments used by

scientific researchers range from about one

percent of Earth’s gravitational acceleration

(aboard aircraft in parabolic flight) to better than

one part in a million (for example, onboard Earthorbiting research satellites).

Quantitative systems of measurement, such as

the metric system, commonly use micro- to mean

one part in a million. Using that definition, the

acceleration experienced by an object in a

Mathematics Standards

∆ ❏ Algebra

∆ Computational and Estimation

❏ Conceptual Underpinnings of Calculus

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Problem Solving

∆ Measurement

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Science as Inquiry

∆ ❏ Unifying Concepts and Processes

F=W+P=mae

Rewriting yields P=mae-mg=m(ae- g).

If your mass is 60 kg and the elevator is aecelerating

upwards at 1 m/s2, your apparent weight is

P=60 kg (+1 m/s2-(-9.8 m/s2))=+648 kg m/s2

while your weight remains

W=mg=(60 kg)(-9.8 m/s2)=-588 kg m/s2.

If the elevator aceelerates downwards at 0.5 m/s2

,

your apparent weight is

P=60 kg (-0.5 m/s2

-(-9.8 m/s2))=+558 kg m/s2.

Mathematics Standards

∆ ❏ Mathematics as Communications

∆ ❏ Mathematics as Reasoning

Science Standards

∆ ❏ Science as Inquiry

∆ ❏ Science in Personal and Social Perspectives

∆ ❏ Unifying Concepts and Processes

1 micro-g or 1 μg = 1 x 10-6 g

Questions for Discussion

• What other eommon prefixes or abbreviations tor powers of

ten do you know or ean you find ?

• In what everyday places do you see these used ?

Grocery stores, farms, laboratories, sporting facilities,

pharmacies, machine shops.

Common prefixes for powers of ten:

10-9 nano- n

10-3 milli- m

102 centi- c

103 kilo- k

106 mega- M

109 giga- G
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

6

Mathematics Standards

∆ ❏ Algebra

∆ Computation and Estimation

❏ Conceptual Underpinnings of Calculus

❏ Discrete Mathematics

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Problem Solving

∆ ❏ Mathematics as Reasoning

∆ Number and Number Relationships

Science Standards

∆ ❏ Unifying Concepts and Processes

Calculate the times in these examples. Teachers can

use these examples at several different scholastic

levels.

Provide the equation as:

Provide the equation as d=(1/2) as t2

, and have the

students re-order the equation.

Making measurements and calculating results involve

the concepts of accuracy and precision, significant figures, and

orders of magnitude. With these concepts in mind, are the drop

times given in the text “correct”?

Mathematics Standards

∆ ❏ Algebra

∆ Computation and Estimation

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Problem Solving

∆ ❏ Mathematics as Reasoning

∆ Measurement

Science Standards

∆ ❏ Science and Technology

∆ ❏ Science as Inquiry

∆ ❏ Unifying Concepts and Processes

Questions for Discussion

• How far away is the Mooon?

• How far away is the center of Earth from the center

of the Moon?

• Why did we ask the previous question?

• How far away is the surface of Earth from the surface

of the Moon

• What are the elevations of different features of

Earth and the Moon?

• How are elevations measured?

microgravity environment would be one-millionth

(10-6) of that experienced at Earth’s surface. The

use of the term microgravity in this guide will

correspond to the first definition. For illustrative

purposes only, we provide the following simple

example using the quantitative definition. This

example attempts to provide insight into what

might be expected if the local acceleration

environment would be reduced by six orders of

magnitude from 1 g to 10-6 g,

If you dropped a rock from a roof that was five

meters high, it would take just one second to

reach the ground. In a reduced gravity

environment with one percent of Earth’s

gravitational pull, the same drop would take 10

seconds. In a microgravity environment equal to

one-millionth of Earth’s gravitational pull, the

same drop would take 1,000 seconds or about 17

minutes!

Researchers can create microgravity conditions in

two ways. Because gravitational pull diminishes

with distance, one way to create a microgravity

environment (following the quantitative definition)

is to travel away from Earth. To reach a point

where Earth’s gravitational pull is reduced to

onemillionth cf that at the surface, you would

have to travel into space a distance of 6.37

million kilometers from Earth (almost 17 times

farther away than the Moon, 1400 times the

highway distance between New York City and Los

Angeles, or about 70 million football fields). This

approach is impractical, except for automated

spacecraft, because humans have yet to travel

farther away from Earth than the distance to the

Moon. However, freefall can be used to create a

microgravity environment consistent with our

primary definition of microgravity. We discuss

this in the next section.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

7

Creating Microgravity

As illustrated in the elevator examples in the

previous section, the effects of gravity (apparent

weight) can be removed quite easily by putting

anything (a person, an object, an experiment) into

a state of freefall. This possibility of using Earth’s

gravity to remove the effects of gravity within a

system were not always evident. Albert Einstein

once said, “I was sitting in a chair in the patent

office at Bern when all of a sudden a thought

occurred to me: ‘If a person falls freely, he will not

feel his own weight.’ I was startled. This simple

thought made a deep impression on me. It

impelled me toward a theory of gravitation.”

Working with this knowledge, scientists involved

in early space flights rapidly concluded that

micro-gravity experiments could be performed by

crew members while in orbit.

Gravity and Distance

The inverse square relationship between gravitational force and

distance can be used to determine the acceleration due to gravity

at any distance from the center of Earth, r.

F = Gmem/re

2 force of gravity due to Earth on a mass,

m, at Earth’s surface

F = mg ➔ g = Gme

/re

2

F = Gmem/r2 force of gravity due to Earth on a mass,

m, at a distance, r, from Earth’s center

F = ma ➔ a = Gme/r2

gre

2

 = ar2

a = gre

2

/r2 acceleration due to Earth’s gravity at

distance, r, from Earth’s center

A typical altitude for a Space Shuttle Orbiter orbit is 296 km. The

Earth’s mean radius is 6.37x106

 m. The acceleration due to

gravity at the Orbiter’s altitude is

a = 9.8 m/s2 (6.37x106 m)2 / (6.67x106 m)2 = 8.9 m/s2

This is about 90% of the acceleration due to gravity at Earth’s

surface. Using the same equations, you can see that to achieve a

microgravity environment of 10-6 g by moving away from Earth,

a research laboratory would have to be located 6.37x109

 m from

the center of Earth.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

8

Mathematics Standards

∆ ❏ Algebra

∆ Computation and Estimation

❏ Conceptual Underpinnings of Calculus

❏ Discrete Mathematics

❏ Functions

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Problem Solving

∆ ❏ Mathematics as Reasoning

∆ Patterns and Functions

∆ ❏ Statistics

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Science as Inquiry

∆ ❏ Science in Personal and Social Perspectives

∆ ❏ Unifying Concepts and Processes

Questions for Discussion

• What is the functional relationship between acceleration,

distance, and time?

Use the four sets of drop facility data points given in the text

and the additional data set (0 meters, 0 seconds). What does

the (0 meters, 0 seconds) data set represent? Why is it a valid

data set to use?

Suggested solution methods: Use different types of graph

paper Use a computer e urvefitting r)rogrnm Do a dimensional

analysis.

• Knowing that g=9.8 m/s2

, what equation can you write to

incolporate acceleration, distance, and time?

• Assume it costs $5,000 per meter of height to build a drop

tower.

How much does it cost to build a drop tower to allow drops of

1 second, 2 seconds, 4 seconds, 10 seconds?

Why does it cost so much more for the longer times?

What would be an inexpensive way to double lowgravity time in a drop tower?

Shoot the experiment package up from the bottom.

The use of orbiting spacecraft is one method

used by NASA to create microgravity conditions.

In addition, four other methods of creating such

conditions are introduced here and we give

examples of situations where the student can

experience microgravity.

Drop Facilities

Researchers use high-tech facilities based on the

elevator analogy to create micro-gravity

conditions. The NASA Lewis Research Center has

two drop facilities. One provides a 132 meter

drop into a hole in the ground similar to a mine

shaft. This drop creates a reduced gravity

environment for 5.2 seconds. A tower at Lewis

allows for 2.2 second drops down a 24 meter

structure. The NASA Marshall Space Flight Center

has a different type of reduced gravity facility.

This 100 meter tube allows for drops of 4.5

second duration. Other NASA Field Centers and

other countries have additional drop facilities of

varying sizes to serve different purposes. The

longest drop time currently available (about 10

seconds) is at a 490 meter deep vertical mine

shaft in Japan that has been converted to a drop

facility. Sensations similar to those resulting from

a drop in these reduced gravity facilities can be

experienced on freefall rides in amusement parks

or when stepping off of diving platforms.

Schematic of the NASA Lewis Research Center 2.2 Second

Drop Tower.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

9

Aircraft

Airplanes are used to achieve reduced gravity

conditions for periods of about 15 seconds. This

environment is created as the plane flies on a

parabolic path. A typical flight lasts two to three

hours allowing experiments and crew members to

take advantage of about forty periods of

microgravity. To accomplish this, the plane climbs

rapidly at a 45 degree angle (this phase is called

pull up), traces a parabola (pushover), and then

descends at a 45 degree angle (pull out). During

the pull up and pull out segments, crew and

experiments experience accelerations of about 2

g. During the parabola, net accelerations drop as

low as 1.5x10-2 g for about 15 seconds. Due to

the experiences of many who have flown on

parabolic aircraft, the planes are often referred to

as “Vomit Comets.” Reduced gravity conditions

created by the same type of parabolic motion

described above can be experienced on the series

of “floater” hills that are usually located at the end

of roller coaster rides and when driving over

swells in the road.

Parabolic Flight Characteristics

Mathematics Standards

❏ Conceptual Underpinnings of Calculus

❏ Functions

∆ ❏ Mathematical Connections

∆ Patterns and Functions

Science Standards

∆ ❏ Earth and Space Science

∆ ❏ Physical Science

∆ ❏ Unifying Concepts and Processes

Microgravity carriers and other spacecraft follow paths best

described by conic sections. The aircraft and sub-orbital rockets

trace out parabolas. Orbiting spacecraft are free falling on

elliptical paths. When a meteoroid is on a path that is influenced

by Earth or any other planetary body but does not get captured

by the gravitational field of the body, its motion, as it approaches

then moves away from the body, traces out a hyperbolic path.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

10

Rocket Parabolic Flight Profile

Mathematics Standards

∆ ❏ Algebra

∆ Computation and Estimation

❏ Conceptual Underpinnings of Calculus

❏ Discrete Mathematics

❏ Functions

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Problem Solving

∆ ❏ Mathematics as Reasoning

∆ Number and Number Relationships

Science Standards

❏ Physical Science

∆ ❏ Science and Technology

❏ Science as Inquiry

❏ Unifying Concepts and Processes

Questions for Discussion

• How does the Shuttle stay in orbit? Use the following two

equations that descnbe the foree aeting on an object. The first

equation represents the force of gravity acting on the Shuttle.

Where:

F1 = Force of gravity acting on the Shuttle

G = Universal gravitational constant

me = Mass of Earth

ms = Mass of the Shuttle

r = Distance from center of Earth to the Shuttle

Rockets

Sounding rockets are used to create reduced

gravity conditions for several minutes; they follow

suborbital, parabolic paths. Freefall exists during

the rocket’s coast: after burn out and before

entering the atmosphere. Acceleration levels are

usually around 10-5 g. While most people do not

get the opportunity to experience the

accelerations of a rocket launch and subsequent

freefall, springboard divers basically launch

themselves into the air when performing dives

and they experience microgravity conditions until

they enter the water.

Orbiting Spacecraft

Although drop facilities, airplanes, and rockets

can establish a reduced gravity environment, all

these facilities share a common problem. After a

few seconds or minutes, Earth gets in the way

and freefall stops. To conduct longer scientific

investigations, another type of freefall is needed.

To see how it is possible to establish microgravity

conditions for long periods of time, one must first

understand what keeps a spacecraft in orbit. Ask

any group of students or adults what keeps

satellites and Space Shuttles in orbit and you

will probably get a variety of answers. Two

common answers are “The rocket engines keep

firing to hold it up,” and “There is no gravity in

space.”

Although the first answer is theoretically possible,

the path followed by the spacecraft would

technically not be an orbit. Other than the altitude

involved and the specific means of exerting an

upward force, little difference exists between a

spacecraft with its engines constantly firing and

an airplane flying around the world. A satellite

could not carry enough fuel to maintain its

altitude for more than a few minutes. The second

answer is also wrong. At the altitude that the

Space Shuttle typically orbits Earth, the

gravitational pull on the Shuttle by Earth is about

90% of what it is at Earth’s surface.

F1

 = G me

ms

r2
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

11

In a previous section, we indicated that Issac

Newton reasoned that the closed orbits of the

planets through space were due to gravity’s

presence. Newton expanded on his conclusions

about gravity and hypothesized how an artificial

satellite could be made to orbit Earth. He

envisioned a very tall mountain extending above

Earth’s atmosphere so that friction with the air

would not be a factor. He then imagined a cannon

at the top of that mountain firing cannonballs

parallel to the ground. Two forces acted upon

each cannonball as it was fired. One force, due to

the explosion of the black powder, propelled the

cannonball straight outward. If no other force

were to act on the cannonball, the shot would

travel in a straight line and at a constant velocity.

But Newton knew that a second force would act

on the cannonball: gravity would cause the path

of the cannonball to bend into an arc ending at

Earth’s surface.

The second equation represents the force acting on the Shuttle

that causes a centripetal acceleration,

This is an expression of Newton’s second law, F=ma.

F2 = Force acting on the Shuttle that causes uniform

circular motion (with centripetal acceleration)

v = Velocity of the Shuttle

These two forces are equal: Fl=F2

 V =

In order to stay in a circular orbit at a given distance from the

center of Earth, r, the Shuttle must travel at a precise velocity, v.

• How does the Shuttle change its altitude? From a detailed

equation relating the Shuttle velocity with the Shuttle altitude,

one can obtain the following simple relationship for a circular

orbit. Certain simplifying assumptions are made in developing

this equation: 1) the radius of the Shuttle orbit is nearly the

same as the radius of Earth, and 2) the total energy of the

Shuttle in orbit is due to its kinetic energy, 1/2 mv2; the change

in potential energy associated with the launch is neglected.

∆r = ∆v

τ = orbital period. the time it takes thc Shuttle to complete

one revolution around Earth

=

∆v = the change in Shuttle velocity

∆r = the change in Shuttle altitude

v2

r

G =

me

ms

r

2

msv2

r

v2 =

Gme

r

τ

π

2 π r 3/2

(Gme) 1/2

Gm

r

e

Illustration from Isaac Newton, Principia, VII,

Book III, p. 551.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

12

For example:

Consider a Shuttle in a circular orbit at 160 nautical miles (296.3

km) altitude. Determine the new altitude caused by the Shuttle

firing a thruster that increases its velocity by I m/s.

First, calculate the orbital period, X, from the above equation.

τ = 2π(re+2.96 x l05

 m)3/2

 (Gme) 1/2

 = 2π(6.37 x 106m+2.96 x 105 m)3/2

 (6.67 x 10-11 m3 x 5.98 x1024kg)l/2

 s2kg

 = 5.41 x 103

 s

Next, use the period and the applied velocity change to calculate

the altitude change.

 τ

 = 5.41x103

s

 = 1.72xl03

 m

This altitude change is actually seen on the opposite side of the

orbit. In order to make the orbit circular at the new altitude, the

Shuttle needs to apply the same ∆v at the other side of the orbit.

In the discussion and example just given, we state that the

equations given are simple approximations of more complex

relationships between Shuttle velocity and altitude. The more

complex equations are used by the Shuttle guidance and

navigation teams who track the Shuttles’ flights. But the

equations given here can be used for quick approximations of the

types of thruster firings needed to achieve certain altitude

changes. This is helpful when an experiment team may want to

request an altitude change. Engineers supporting the experiment

teams can determine approximately how much propellant would

be required for such an altitude change and whether enough

would be left for the required de-orbit burns. In this way, the

engineers and experiment teams can see if their request is

realistic and if it has any possibility of being implemented.

Newton considered how additional cannonballs

would travel farther from the mountain each time

the cannon fired using more black powder. With

each shot, the path would lengthen and soon the

cannonballs would disappear over the horizon.

Eventually, if one fired a cannon with enough

energy, the cannonball would fall entirely around

Earth and come back to its starting point. The

cannonball would be in orbit around Earth.

Provided no force other than gravity interfered

with the cannonball’s motion, it would continue

circling Earth in that orbit.

This is how the Space Shuttle stays in orbit. It

launches on a path that arcs above Earth so that

the Orbiter travels at the right speed to keep it

falling while maintaining a constant altitude above

the surface. For example, if the Shuttle climbs to

a 320 kilometer high orbit, it must travel at a

speed of about 27,740 kilometers per hour to

achieve a stable orbit. At that speed and altitude,

the Shuttle executes a falling path parallel to the

curvature of Earth. Because the Space Shuttle is

in a state of freefall around Earth and due to the

extremely low friction of the upper atmosphere,

the Shuttle and its contents are in a high-quality

microgravity environment.

∆r= π

(1 m/s )

π

∆v
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

13

Microgravity

Science Primer

We experience many manifestations of gravity on

a day to day basis. If we drop something, it falls

toward Earth. If we release a rock in a container of

water, the rock settles to the bottom of the container. We experience other effects of gravity

regularly, although we may not think of gravity as

playing a role.

Consider what happens when a container of water

is heated from below. As the water on the bottom

is heated by conduction through the container, it

becomes less dense than the un-heated, cooler

water. Because of gravity, the cooler, more dense

water sinks to the bottom of the container and the

heated water rises to the top due to buoyancy. A

circulation pattern is produced that mixes the hot

water with the colder water. This is an example of

buoyancy driven (or gravity driven) convection.

The convection causes the water to be heated

more quickly and uniformly than if it were heated

by conduction alone. This is the same density

driven convection process to which we refer when

we state matter-of-factly that”hot air rises.”

In addition to mixing, density differences can also

cause things to differentially settle through a

process called sedimentation. In this process, the

more dense components of mixtures of

immiscible fluids or solid particles in fluids sett’e

to the bottom of a container due to gravity. If you

fill a bucket with very wet mud, and then leave the

bucket sitting on the ground, over time the more

dense soil particles will sink to the bottom of the

bucket due to gravity, leaving a layer of water on

top. When you pick up a bottle of Italian salad

dressing from the grocery store shelf, you see

several different layers in the bottle. The dense

solids have settled to the bottom, the vinegar

forms a middle layer, and the least dense oil is on

top.

Science Standards

∆ ❏ Physical Science

∆ ❏ Unifying Concepts and Processes

Heat transfer occurs through one of three processes or a

combination of the three. Conduction is the flow of heat through

a body from an area of higher temperature to an area of lower

temperature. Molecules in the hot region increase their

vibrational energy as they are heated. As they collide with

molecules with lower vibrational energy (cooler ones). some of

the vibrational energy is passed to the cooler ones, their energy is

incrcased. and heat is passed on.

Heat transfer by convection is the movement of heat by motion

of a fluid. This motion can he the result of some force, such as a

pump circulating heated water. and is referred to as forced

convection. If the motion is the result of difterences in density

(thermal or compositional). the convection is referred to as

buoyancy-driven, density-driven. or natural convection.

Radiation is the emission of energy trom the surface of a body.

Energy is emitted in the form of electromagnetic waves or

photons (packets of light). The character (wavelength. energy of

photons, etc.) of the radiation depends on the temperature.

surface area. and characteristics of the body emitting the energy.

Electromagnetic waves travel with the speed of light through

empty space and are absorbed (and/or reflected) by objects they

fall on, thus transferring heat. An excellent example of radiative

heating is the sun’s heat that we experience on Earth.

Mathemathics Standards

∆ ❏ Mathematical Conneclions

Science Standards

∆ ❏ Earth and Space Science

∆ ❏ Physical Science

∆ ❏ Unifying Concepts and Processes

The mass of a body divided hy its volume is its average density.

Science Standards

∆ ❏ Physical Science

∆ ❏ Unifying Concepts and Processes

When two or more liquids are immiscible they do not mix

chemically.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

14

Density Table Units (kg/m3)

Interstellar space 10-21 - 10-18

Atmosphere at normal altitude

of Space Shuttle in orbit 1-4x10-11

Air at 0°C and 1 atm 1.3

Carbon Dioxide 1.9

Balsa 110-140

Bone 170-200

Cork 220-260

The Larch 500-560

Lithium 530

Applewood 660-840

Peat Blocks 840

Ice 920

Olive Oil 920

Sodium 970

Water at 0°C and 1 atm 1000

Rock Salt 2180

Graphite 2300-2700

Alunıinum 2700

Basalt 2400-3100

Talc 2700-2800

Dolomite 2830

Diamond 3010-3520

Average density of Earth 5520

Iron 7860

Lead 11340

Irdium 22400

Osmium 22500

Uranium nucleus 3x1017

Neutron star (center) 1017-1018

Mathematics Standards

∆ ❏ Algebra

❏ Functions

∆ Geometry

❏ Geometry from a Synthetic Perspective

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Communication

∆ ❏ Mathematics as Problem Solving

∆ Measurement

❏ Trigonometry

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Science in Personal and Social Perspectives

∆ ❏ Unifying Concepts and Processes

Gravity can also mask some phenomena that

scientists wish to study. An example is the

process of diffusion. Diffusion is the intermingling

of solids, liquids, and gases due to differences in

composition. Such intermingling occurs in many

situations, but diffusion effects can be easily

hidden by stronger convective mixing. As an

example, imagine a large room in which all air

circulation systems are turned off and in which a

group of women are spaced ten feet apart

standing in a line. If an open container of

ammonia were placed in front of the first woman

in line and each woman raised her hand when she

smelled the ammonia, it would take a

considerable amount of time before everyone

raised her hand. Also, the hand raising would

occur sequentially along the line from closest to

the ammonia to furthest from the ammonia. If the

same experiment were performed with a fan

circulating air in the room, the hands would be

raised more quickly, and not necessarily in the

same order. In the latter case, mixing of the

ammonia gas with the air in the room is due to

both diffusion and convection (forced convection

due to the fan) and the effects of the two

processes cannot be easily separated. In a similar

manner, buoyancy driven convection can mask

diffusive mixing of components in scientific

experiments.

Some behavior of liquids can also be masked by

gravity. If you pour a liquid into a container on

Earth, the liquid conforms to the bottom of the

container due to gravity. Depending on the shape

of the container and on the properties of the

container and the liquid, some of the liquid may

creep up the walls or become depressed along

the walls due to the interrelated phenomena of

surface tension, adhesion, cohesion, and

capillarity.

The resulting curved surface may be familiar to

anyone who has measured water in a small

diameter glass container (the water cups

upward) or has looked at the level of mercury in a

glass thermometer (the mercury cups

downward). The distance the contact
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

15

line between the liquid and the container moves

up or down the container wall is affected by

gravity.

Experiments performed on Earth often take

advantage of the effects of gravity discussed. For

many experiments, however, these effects tend to

make the execution of experiments or the analysis

of experimental results difficult and sometimes

even impossible. Therefore, many researchers

design experiments to be performed under

microgravity conditions. The different scientific

research areas that are studied in microgravity

include biotechnology, combustion science, fluid

physics, fundamental physics, and materials

science. Each of these areas, or disciplines, is

discussed below. The discipline is defined, some

of the specific effects of gravity that illustrate the

benefits of microgravity research are discussed,

and some examples of current research are

presented. In addition, a brief discussion of the

microgravity environment of orbiting spacecraft is

provided as is an introduction to the application

of microgravity research to the exploration and

development of space.

The Microgravity

Environment of

Orbiting Spacecraft

While freefall reduces the effects of gravity, being

in an orbiting laboratory introduces other

accelerations that cause effects that are

indistinguishable from those due to gravity. When

a spacecraft is in orbit around Earth, the orbit is

actually defined by the path of the center of mass

of the spacecraft around the center of Earth. Any

object in a location other than on the line

traversed by the center of mass of the spacecraft

is actually in a different orbit around Earth.

Because of this, all objects not attached to the

spacecraft move relative to the orbiter center of

mass. Other relative motions of unattached

objects are related to aerodynamic drag on the

Capillarity can be defined as the attraction a fluid has for itself

versus the attraction it has for a solid surface (usually the fluid’s

container). Thc surface tension σ in a liquid-liquid or liquid-gas

system is the fluids’ tendency to resist an increase in surface area.

Surface tension is temperature dependent. Surface tension,

capillarity, adhesion, and cohesion work together to drive the

contact angle θ between a solid-liquid interface and liquid-liquid

interface when a small diameter tube is dipped into a liquid.

When the contact angle θ=0, the liquid “wets” the tubc

completely. When θ<90° (an acute angle), the liquid rises in the

tube; when θ>90° (an obtuse angle). the liquid is depressed in the

tube and does not wet the walls. The distance belween the liquid

suri’ace in the container and in the tube is h=2<σcosθ/rρg where

r is the radius of the tube (D/2), ρ is the density of the liquid, and

g is the acceleration due to gravity.

Mathematics Standards

❏ Functions

∆ Geometry

❏ Geometry from a Synthetic Perspective

Science Standards

∆ ❏ Science and Technology

∆ ❏ Science in Personal and Social Perspectives

∆ ❏ Unifying Concepts and Processes

Something that is concave is curved inward like the inner surface

of a sphere. Something that is convex is curved like the outer

surfiace of a sphere. A variety of concave and convex lenses and

mirrors are used in the design of eyeglasses, magnifying glasses,

cameras, microscopes, and telescopes. In the cxample in the text,

water cupping upward produces a concave surface; mercury

cupping downward produces a convex surface.

θ

h

D

ρ

h

θ

ρ

D
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

16

Mathematics Standards

∆ Computation and Estimation

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Communication

∆ Measurement

Science Standards

Grades 5-8 (∆); Grades 9-12 (❏)

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Unifying Concepts and Processes

Quasi-steady accelerations in spacecraft are related to the

position in the spacecraft, aerodynamic drag, and vehicle

rotation. For the Space Shuttle Orbiters, these accelerations are

on the order of lx10-6 g and vary with the orbital frequency.

Mathematics Standards

∆ Computation and Estimation

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Communication

∆ Measurement

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Unifying Concepts and Processes

g-jitter indicates the vibrations expenenced by microgravity

expenments (for example on parabolic aircraft and the Space

Shuttle) that cause effects similar to those that would be caused

by a time-varying gravitational field.

The quasi-steady microgravity environment on the Orbiter

Columbia shows the effiects of variations in Earth’s atmospheric

density. The primary contribution to the variation is the day/night

diffierence in atmospheric density. The plot shows that the drag

on the Orbiter varies over a ninety minute orbit.

vehicle and spacecraft rotations. A spacecraft in

low-Earth orbit experiences some amount of drag

due to interactions with the atmosphere. An

object within the vehicle, however, is protected

from the atmosphere by the spacecraft itself and

does not experience the same deceleration that

the vehicle does. The floating object and

spacecraft therefore are moving relative to each

other. Similarly, rotation of the spacecraft due to

orbital motion causes a force to act on objects

fixed to the vehicle but not on objects freely

floating within it. On average for the Space

Shuttles, the quasi-steady accelerations

resulting from the sources discussed above

(position in the spacecraft, aerodynamic drag,

and vehicle rotation) are on the order of 1x1 0-6 g,

but vary with time due to variations in the

atmospheric density around Earth and due to

changes in Shuttle orientation.

In addition to these quasi-steady accelerations,

many operations on spacecraft cause vibrations

of the vehicle and the payloads (experiment

apparatus). These vibrations are often referred to

as g-jitter because their effects are similar to

those that would be caused by a time-varying

gravitational field. Typical sources for vibrations

are experiment and spacecraft fans and pumps,

motion of centrifuges, and thruster firings. With a

crew onboard to conduct experiments, additional

vibrations can result from crew activities.

The combined acceleration levels that result from

the quasi-steady and vibratory contributions are

generally referred to as the microgravity

environment of the spacecraft. On the Space

Shuttles, the types of vibration-causing

operations discussed above tend to create a

cumulative background microgravity environment

of about 1x10-4 g, considering contributions for

all frequencies below 250 Hz.

Biotechnology

Biotechnology is an applied biological science

that involves the research, manipulation, and
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

17

manufacturing of biological molecules, tissues,

and living organisms. With a critical and

expanding role in health, agriculture, and

environmental protection, biotechnology is

expected to have a significant impact on our

economy and our lives in the next century.

Microgravity research focuses on three principal

areas—protein crystal growth, mammalian cell

and tissue culture, and fundamental

biotechnology.

Gravity significantly influences attempts to grow

protein crystals and mammalian cell tissue on

Earth. Initial research indicates that protein

crystals grown in microgravity can yield

substantially better structural information than

can be obtained from crystals grown on Earth.

Proteins consist of thousands—or in the case of

viruses, millions—of atoms, which are weakly

bound together, forming large molecules. On

Earth, buoyancy-induced convection and

sedimentation may inhibit crystal growth. In

microgravity, convection and sedimentation are

significantly reduced, allowing for the creation of

structurally better and larger crystals.

The absence of sedimentation means that protein

crystals do not sink to the bottom of their growth

container as they do on Earth. Consequently, they

are not as likely to be affected by other crystals

growing in the solution. Because convective flows

are also greatly reduced in microgravity, crystals

grow in a much more quiescent environment,

which may be responsible for the improved

structural order of space-grown crystals.

Knowledge gained from studying the process of

protein crystal growth under microgravity

conditions will have implications for protein

crystal growth experiments on Earth.

Research also shows that mammalian cells—

particularly normal cells—are sensitive to

conditions found in ground-based facilities used

to culture (grow) them. Fluid flows caused by

gravity can separate the cells from each other,

Protein crystals grown in microgravity can have

regular, simple shapes and a more highly ordered

internal structure than those grown on Earth.

1 g μ g
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

18

severely limiting the number of cells that will

aggregate (come and stay together). But tissue

samples grown in microgravity are much larger

and more representative of the way in which

tissues are actually produced inside the human

body. This suggests that better control of the

stresses exerted on cells and tissues can play an

important role in their culture. These stresses are

greatly reduced in microgravity.

Protein Crystal Growth

The human body contains over 100,000 different

proteins. These proteins play important roles in

the everyday functions of the body, such as the

transport of oxygen and chemicals in the blood,

the formation of the major components of muscle

and skin, and the fighting of disease. Researchers

in this area seek to determine the structures of

these proteins, to understand how a protein’s

structure affects its function, and ultimately to

design drugs that intercede in protein activities

(penicillin is a well-known example of a drug that

works by blocking a protein’s function).

Determining protein structure is the key to the

design and development of effective drugs.

The main purpose in growing protein crystals is

to advance our knowledge of biological molecular

structures. Researchers can use microgravity to

help overcome a significant stumbling block in

the determination of molecular structures: the

difficulty of growing crystals suitable for

structural analysis. Scientists use X-ray

diffraction to determine the three-dimensional

molecular structure of a protein. They can

calculate the location of the atoms that make up

the protein based on the intensity and position of

the spots formed by the diffracted X-rays. From

high resolution diffraction data, scientists can

describe a protein’s structure on a molecular

scale and determine the parts of the protein that

are important to its functions. Using computer

analysis, scientists can create and manipulate

three-dimensional models of the protein and

examine the intricacies of its structure to create a

drug that”fits” into a protein’s active site, like

inserting a key into a lock to “turn off” the

Crystallized protein lysozyme after dialysis to remove small

molecule contaminants.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

19

protein’s function. But X-ray diffraction requires

large, homogeneous crystals (about the size of a

grain of table salt) for analysis. Unfortunately,

crystals grown in Earth’s gravity often have

internal defects that make analysis by X-ray

diffraction difficult or impossible. Space Shuttle

missions have shown that crystals of some

proteins (and other complex biological molecules

such as viruses) grown on orbit are larger and

have fewer defects than those grown on Earth.

The improved data from the space-grown crystals

significantly enhance scientists’ understanding of

the protein’s structure and this information can be

used to support structure-based drug design.

Scientists strive for a better understanding of the

fundamental mechanisms by which proteins form

crystals. A central goal of microgravity protein

crystal growth experiments is to determine the

basic science that controls how proteins interact

and order themselves during the process of

crystallization. To accomplish this goal, NASA has

brought together scientists from the protein

crystallography community, traditional crystal

growers, and other physical scientists to form a

multidisciplinary team in order to address the

problems in a comprehensive manner.

Mammalian Cell and Tissue Culture

Mammalian cell tissue culturing is a major area of

research for the biotechnology community. Tissue

culturing is one of the basic tools of medical

research and is key to developing future medical

technologies such as ex vivo (outside of the

body) therapy design and tissue transplantation.

To date, medical science has been unable to fully

culture human tissue to the mature states of

differentiation found in the body.

The study of normal and cancerous mammalian

tissue growth holds enormous promise for

applications in medicine. However, conventional

static tissue culture methods form flat sheets of

growing cells (due to their settling on the bottom

of the container) that differ in appearance and

function from their three-dimensional counterparts

Science Standards

∆ ❏ Physical Science

∆ ❏ Unifying Concepts and Processes

A substance that is homogeneous is uniform in structure and/or

composition.

Three different types of protein c rystals grown on the

Space Shuttle Columbia in 1995: satellite tobacco mosaic

virus, lysozyme, and thaumatin.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

20

Science Standards

∆ ❏ Life Science

∆ ❏ Unifying Concepts and Processes

Differentiation is the process (or the result of that process) by

which cells and/or tissues undergo a progressive specialization of

form or function.

Mathematics Standards

❏ Algebra

❏ Conceptual Underpinnings of Calculus

❏ Geometry from an Algebraic Perspective

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Problem Solving

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Unifying Concepts and Processes

The forces acting on a surface can be separated into components

perpendicular (normal) to and tangential to the surface. The

normal force causes a normal stress and the tangential force is

responsible for a tangential, or shear, stress acting on the surface.

Shear forces cause contiguous parts of a structure or liquid to

slide relative to each other.

growing in a living body. In an effort to enhance

threedimensional tissue formation, scientists have

developed a ground-based facility for cell and

tissue culture called a bioreactor. This instrument

cultures cells in a slowly rotating horizontal

cylinder, which produces lower stress levels on

the growing cells than previous Earth-based

experimental environments. The continuous

rotation of the cylinder allows the sample to

escape much of the influence of gravity, but

because the bioreactor environment tends to be

rather passive, it is sometimes difficult for the

growing tissue to find the fresh media (food

supply) it needs to survive.

Another reason normal mammalian cells are

sensitive to growth conditions found in standard

bioreactors is that fluid flow causes shear forces

that discourage cell aggregation. This limits both

the development of the tissue and the degree to

which it possesses structures and functions

similar to those found in the human body. Tissue

cultures of the size that can be grown in these

bioreactors allow tests of new treatments on

cultures grown from cells from the patient rather

than on patients themselves. In the future, this

technology will enable quicker, more thorough

testing of larger numbers of drugs and

treatments. Ultimately, the bioreactor is expected

to produce even better results when used in a

microgravity environment.

In cooperation with the medical community, the

bioreactor design is being used to prepare better

models of human colon, prostate, breast, and

ovarian tumors. Cells grown in conventional

culture systems may not differentiate to form a

tumor typical of cancer. In the bioreactor,

however, these tumors grow into specimens that

resemble the original tumor. Similar results have

been observed with normal human tissues as

well. Cartilage, bone marrow, heart muscle,

skeletal muscle, pancreatic islet cells, liver cells,

and kidney cells are examples of the normal

tissues currently being grown in rotating

bioreactors by investigators. In addition,

A bioreactor vessel thatflew on the Space Shuttle Discovery in

July 1995.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

21

laboratory models of heart and kidney diseases,

as well as viral infections (including Norwalk virus

and Human Immunodeficiency Virus (HIV)) are

currently being developed using a modified NASA

bioreactor experiment design with slight

variations in experimental technique and some

adjustments to hardware. Continued use of the

bioreactor can improve our knowledge of normal

and cancerous tissue development. NASA is

beginning to explore the possibility of culturing

tissues in microgravity, where even greater

reduction in stresses on growing tissue samples

may allow much larger tissue masses to develop.

A hioreactor is in use on the Russian Space

Station Mir in preparation for the International

Space Station.

Fundamental Biotechnology

Electrophoresis has been studied on a dozen

Space Shuttle flights and has led to additional

research in fluid physics in the area of

electrohydrodynamics. Phase partitioning

experiments, which use interfacial energy (the

energy change associated with the contact

between two different materials) as the means of

separation, have flown on six missions.

Combustion Science

Combustion, or burning, is a rapid, selfsustaining chemical reaction that releases a

significant amount of heat. Examples of common

combustion processes are burning candles, forest

fires, log fires, the burning of natural gas in home

furnaces, and the burning of gasoline in internal

combustion engines. For combustion to occur,

three things must normally be present: a fuel, an

oxidizer, and an ignition stimulus. Fuels can be

solid, liquid, or gas. Examples of solid fuels

include filter paper, wood, and coal. Liquid fuels

include gasoline and kerosene. Propane and

hydrogen are examples of gaseous fuels.

Oxidizers can be solid (such as ammonium

perchlorate, which is used in Space Shuttle booster

rockets), liquid (like hydrogen peroxide), or gaseous

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Sciences in Personal and Social Perspectives

∆ ❏ Unifying Concepts and Processes

Electrophoresis is the separation of a substance based on the

electrical charge of the molecule and its motion in an applied

electric field.

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Science in Personal and Social Perspectives

∆ ❏ Unifying Concepts and Processes

An exception to the standard combustion process is hypergolic

combustion. In this situation, a fuel and an oxidizer

spontaneously react on contact without the need for an ignition

stimulus. The jets used to maintain and change the Shuttle’s

orientation when in orbit are powered by hypergolic reactions.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

22

(like oxygen). Air, which contains oxygen, is a

particularly common oxidizer. An electrical spark

is an example of an ignition stimulus.

Combustion is a key element in many of modern

society’s critical technologies. Electric power

production, home heating, ground transportation,

spacecraft and aircraft propulsion, and materials

processing are all examples in which combustion

is used to convert chemical energy to thermal

energy. Although combustion, which accounts for

approximately 85 percent of the world’s energy

usage, is vital to our current way of life, it poses

great challenges to maintaining a healthy

environment. Improved understanding of

combustion will help us deal better with the

problems of pollutants, atmospheric change and

global warming, unwanted fires and explosions,

and the incineration of hazardous wastes. Despite

vigorous scientific examination for over a century,

researchers still lack full understanding of many

fundamental combustion processes.

Some objectives of microgravity combustion

science research are to enhance our

understanding of the fundamental combustion

phenomena that are affected by gravity, to use

research results to advance combustion science

and technology on Earth, and to address issues of

fire safety in space. NASA microgravity

combustion science research combines the

results of experiments conducted in groundbased microgravity facilities and orbiting

laboratories and studies how flames ignite,

spread, and extinguish (go out) under

microgravity conditions.

Research in microgravity permits a new range of

combustion experiments in which

buoyancyinduced flows and sedimentation are

virtually eliminated. The effects of gravitational

forces often impede combustion studies

performed on Earth. For example, combustion

generally produces hot gas (due to the energy

reieased in the reaction), which is less dense that

the cooler gases around it. In Earth’s gravity, the

The familiar shape of a candle flame on Earth is

caused by buoyancy-driven convection. In

microgravity, a candle flame assumes a spherical

shape as fresh oxidizer reaches it by diffusion

processes.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

23

hot gas is pusched up by the denser surrounding

gases. As the hot gas rises, it creates buoyancyinduced flow that promotes the mixing of the

unburned fuel, oxidizer, and combustion

products.

The ability to significantly reduce gravity-driven

flows in microgravity helps scientists in several

ways. One advantage is that the “quieter” and

more symmetric microgravity environment makes

the experiments easier to model (describe

mathematically), thus providing a better arena

for testing theories. In addition, eliminating

buoyancy-induced flows allows scientists to study

phenomena that are obscured by the effects of

gravity, such as the underlying mechanisms of

fuel and heat transport during combustion

processes. Because buoyancy effects are nearly

eliminated in microgravity, experiments of longer

duration and larger scale are possible, and more

detailed observation and examination of

important combustion processes can occur.

Scientists often desire an even mixture of the

component parts of fuels so that models

developed for their experiments can use

simplified sets of equations to represent the

processes that occur. Sedimentation affects

combustion experiments involving particles or

droplets because, as the components of greater

density sink in a gas or liquid, their movement

relative to the other particles creates an

asymmetrical flow around the dropping particles.

This can complicate the interpretation of

experimental results. On Earth, scientists must

resort to mechanical supports, levitators, and

stirring devices to keep fuels mixed, while fluids

in microgravity stay more evenly mixed without

sticking together, colliding, or dispersing

unevenly.

Mathematics Standards

∆ Computation and Estimation

❏ Discrete Mathematics

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Communication

∆ ❏ Mathematics as Problem Solving

∆ ❏ Mathematics as Reasoning

Science Standards

∆ ❏ Physical Science

∆ ❏ Science as Inquiry

∆ ❏ Science and Technology

∆ ❏ Unifying Concepas and Processes

The creation and use of mathematical models is a key element

of science, engineering, and technology. Modeling begins with

identifying the physical and chemical phenomena involved in an

experiment. Associated mathematical equations such as equations

of motion are then identified. These governing equations are

solved in order to predict important aspeces of the experiment

behavior, using appropriate values of experiment parameters such

as density, composition, temperature, and pressure. Simple

mathematical models can be solved hy hand, while more

complex experiments are generally modeled using sophisticated

algorithms on high speed computers.

In microgravity research, scientists use modeling in preparation

for flight experiments and in analysis of the results. Models and

experiment procedures are fine-tuned based on comparisons

between model predictions and the results of ground-based

microgravity experiments (for example, drop facilities and

parabolic aircraft flights). This preliminary work allows

researchers to best take advantage of space flight opportunities.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

24

To date, combustion science researchers have

demonstrated major differences in the structures

of various types of flames burning under

microgravity conditions and under 1 g conditions.

In addition to the practical implications of these

results in combustion efficiency, pollutant control,

and flammability, these studies establish that

better understanding of the individual processes

involved in the overall combustion process can be

obtained by comparing results from microgravity

and Earth gravity tests. One clear example of the

advantage of these comparison tests is in the area

of fire safety. Most smoke detectors have been

designed to detect soot particles in the air, but the

sizes of soot particles produced in 1 g are

different from those produced in microgravity

environments. This means that smoke-detecting

equipment must be redesigned for use on

spacecraft to ensure the safety of equipment and

crew.

Comparisons of research in microgravity and in

1 g have also led to improvements in combustion

technology on Earth that may reduce pollutants

and improve fuel efficiency. Technological

advances include a system that measures the

composition of gas emissions from factory

smoke stacks so that they can be monitored. In

addition, a monitor for ammonia, which is one

gas that poses dangers to air quality, is already

being produced and is available for industrial use.

Engineers have also designed a device that allows

natural gas appliances to operate more efficiently

while simultaneously reducing air pollution. This

may be used in home furnaces, industrial

processing furnaces, and water heaters in the

future. Another new technology is the use of

advanced optical diagnostics and lasers to better

define the processes of soot formation so that

soot-control strategies can be developed. Devices

have also been developed to measure percentages

of soot in exhausts from all types of engines and

combustors, including those in automobiles and

airplanes.

Transmission Electron Microscope image of laserheated soot.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

25

The combustion science program supports

experiments in the following research areas:

Premixed Gas Flames

In premixed gas flame research, the fuel and

oxidizer gases are completely mixed prior to

ignition. Scientists are interested in flame speed

(the rate at which the flame zone travels away

from the ignition source and into the unreacted

mixture) as a function of both the type of fuel and

oxidizer used and the oxidizer-to-fuel ratio. With

sufficiently high or low ratios, the flame does not

move into the unreacted mixture; these critical

ratios are referred to as lower and upper

flammability limits and are of considerable

interest in terms of both safety and fundamental

science. Gravity can strongly affect both flame

speed and flammability limits, chiefly through

buoyancy effects. Scientists in this area are also

researching gravity’s effects on the stability,

extinction, structure, and shape of premixed gas

flames.

Gaseous Diffusion Flames

In this area of research, the fuel and oxidizer

gases are initially separate. They tend to diffuse

into each other and will react at their interface

upon ignition. The structure of these flames under

microgravity conditions is quite different than on

Earth because of buoyancy-induced flows caused

by Earth’s gravity. Scientists study flammability

limits, burning rates, and how diffusion flame

structure affects soot formation. Within this area,

results of studies of the behavior of gas-jet flames

in a microgravity environment, both in transition

and in turbulent flows, are being used to develop

models with potential applications in creating

effective strategies to control soot formation in

many practical applications.

Liquid Fuel Droplets and Sprays

In this research area, scientists study the

combustion of individual liquid fuel droplets

suspended in an oxidizing gas (air, for example).

For these experiments, investigators commonly

use fuels

Candle flame energy flow. Adapted from “The Science of Flames”

poster, National Energy Foundation, Salt Lake City, Utah.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

26

Ultraviolet images of OH radiation taken at hnIf:vecnnd

interval.s during a drrvp tower test of the Droplet

Combustion Experiment. The diameter of the flame produced

by burning a heptane droplet decreases in freefall.

such as heptane, kerosene, and methanol. Gravity

hinders fundamental studies of droplet

combustion on Earth due to flows induced by

high-density droplets that sink and

buoyancyinduced upward acceleration of hot

combustion products relative to the surrounding

gas. These flows cause drops to burn unevenly,

making it difficult for scientists to draw

meaningful conclusions from their experiments.

This area of study also includes the investigation

of the combustion of sprays and ordered arrays

of fuel droplets in a microgravity environment for

an improved understanding of interactions

between individual burning droplets in sprays.

Knowledge of spray combustion processes

resulting from these studies should lead to major

improvements in the design of combustors using

liquid fuels.

Fuel Particles and Dust Clouds

This area is particularly important in terms of fire

safety because clouds of coal dust have the

potential to cause mine explosions and grain-dust

clouds can cause silos and grain elevators to

explode. It is particularly difficult to study the

fundamental combustion characteristics of fueldust clouds under normal gravity because initially

welldispersed dust clouds quickly settle due to

density differences between the particles and the

surrounding gas. Because particles stick together

and collide during the sedimentation process,

they form nonuniform fuel-air ratios throughout

the cloud. In microgravity, fuel-dust clouds

remain evenly mixed, allowing scientists to study

them with much greater experimental control with

a goal of mitigating coal mine and grain elevator

hazards.

Flame Spread Along Surfaces

An important factor in fire safety is inhibiting the

spread of flames along both solid and liquid

surfaces. Flame spread involves the reaction

between an oxidizer gas and a condensed-phase

fuel or the vapor produced by the “cooking” of
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

27

such a fuel. Research has revealed major

differences in ignition and flame-spreading

characteristics of liquid and solid fuels under

microgravity and normal gravity conditions.

Material flammability tests in 1 g, which are

strongly affected by buoyancy-induced flows, do

not match results obtained in microgravity. It is

therefore useful to study both flame spread and

material flammability characteristics in

microgravity to ensure fire safety in environments

with various levels of gravity. The knowledge

gained from these studies may also lead to better

understanding of dangerous combustion

reactions on Earth. Microgravity experiments

eliminate complexities associated with buoyancy

effects, providing a more fundamental scenario

for the development of flame-spreading theories.

Smoldering Combustion

Smoldering combustion is a relatively slow,

nonflaming combustion process involving an

oxidizer gas and a porous solid fuel. Well-known

examples of smoldering combustion are

“burning” cigarettes and cigars. Smoldering

combustion can also occur on much larger scales

with fuels such as polyurethane foam. When a

porous fuel smolders for a long period of time, it

can create a large volume of gasified fuels, which

are ready to react suddenly if a breeze or some

other oxidizer flow occurs. This incites the fuel to

make the transition to full-fledged combustion,

often leading to disastrous fires (like those

involving mattresses or sofa cushions). Since

heat is generated slowly in this process, the rate

of combustion is quite sensitive to heat exchange;

therefore, buoyancy effects are particularly

important. Accordingly, smoldering combustion is

expected to behave quite differently in the

absence of gravity.

Combustion Synthesis

Combustion synthesis, a relatively new area of

research, involves creating new materials through

a combustion process and is closely tied to work

in materials science. One area of particular

interest is referred to as self-deflagrating highView looking down at a piece qf ashless filter paper with a 1

centimeter grid on it. On the USMP-3 Shuttle mission, a radiant

heater (two concentric rings exposed at the center of the image)

was used to ignite samples to study flame spread and smoldering

in weak air f1ows under microgravity conditions. In this image,

areas where the grid is not seen have been burned, with the

cracking and curling edges of the burning paper leaving a cusped

appearance. The flame started at the heater site and propagated

toward the right where a fan provided a source of fresh air.

Charred paper around the burnt area is a darker grey than the

uraffected paper. White areas to the right of the heater rings are

soot zones.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

28

Science Standards

∆ ❏ Physical Science

∆ ❏ Unifying Concepts and Processes

A fluid is something that flows. Highly compressible fluids are

usually considered gases; essentially incompressible fluids are

usually considered liquids. Fluids tend to conform to the shape of

a container. On Earth’s surface, liquids tend to fill the bottom of

an open or closed container and gases tend to fill closed

containers.

temperature synthesis. This occurs when two

materials— usually two solids—are mixed

together, are reactive with one another, and create

a reaction that gives off a large amount of heat.

Once the reaction is started, the flame will

propagate through a pressed mixture of these

particles, resulting in a new material. Much of the

initial research in this groundbreaking area

involves changing variables such as composition,

pressure, and preheat temperature. Manipulating

these factors leads to interesting variations in the

properties of materials created through the

synthesis process.

Flame processes are also being used to create

fullerenes and nanoparticles. Fullerenes, a new

form of carbon, are expensive to produce at this

time and cannot be produced in large quantities,

but scientists predict more uses for them will be

developed as they become more readily available.

Nanoparticles (super-small particles) are also of

great interest to materials scientists due to the

changes in the microstructure of compacted

materials that can be produced by sintering,

which results in improved properties of the final

products. These nanoparticles can thus be used

to form better pressed composite materials.

Fluid Physics

A fluid is any material that flows in response to

an applied force; thus, both liquids and gases are

fluids. Some arrangements of solids can also

exhibit fluid-like behaviors; granular systems

(such as soil) can respond to forces, like those

induced by earthquakes or floods, with a flow-like

shift in the arrangement of solid particles and the

air or liquids that fill the spaces between them.

Fluid physicists seek to better understand the

physical principles governing fluids, including

how fluids flow under the influence of energy,

such as heat or electricity; how particles and gas

bubbles suspended in a fluid interact with and

change the properties of the fluid; how fluids

interact with solid boundaries; and how fluids

change phase, either from fluid to solid or from one

fluid phase to another. Fluid phenomena studied
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

29

range in scale from microscopic to atmospheric

and include everything from the transport of cells

in the human body to changes in the composition

of the atmosphere.

The universal nature of fluid phenomena makes

their study fundamental to science and

engineering. Understanding the fluid-like behavior

of soils under stress will help civil engineers

design safe buildings in earthquake-prone areas.

Materials engineers can benefit from a better

grasp of how the structure and properties of a

solid metal are determined by fluid behavior

during its formation. And knowledge of the flow

characteristics of vapor-liquid mixtures is useful

in designing power plants to ensure maximum

stability and performance. The work of fluid

physics researchers often applies to the work of

other microgravity scientists.

Complex Fluids

This research area focuses on the unique

properties of complex fluids, which include

colloids, gels, magneto-rheological fluids, foams,

and granular systems.

Colloids are suspensions of finely divided solids

or liquids in fluids. Some examples of colloidal

dispersions are aerosols (liquid droplets in gas),

smoke (solid particles in gas), and paint (solid in

liquid). Gels are colloidal mixtures of liquids and

solids in which the solids have linked together to

form a continuous network, becoming very

viscous (resistant to flow). Magneto-rheological

fluids consist of suspensions of colloidal

particles. Each particle contains many tiny,

randomly oriented magnetic grains and an

externally applied magnetic field can orient the

magnetic grains into chains. These chains may

further coalesce into larger-scale structures in the

suspension, thereby dramatically increasing the

viscosity of the suspension. This increase,

however, is totally reversed when the magnetic

field is turned off.

Side views of water and airflowing through a clearpipe. At Ig,

the air stays on top. In microgravity, the air canform a core

down the center of the pipe.

1 g

μ g
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

30

Science Standards

∆ ❏ Physical Science

∆ ❏ Unifying Concepts and Processes

Rheology is the scientific study of the deformation and flow of

matter.

USML-2 Payload Commander Kathryn C. Thomton works at the

Drop Physics Module, used to investigate liquid drop behavior in

microgravity.

A foam is a nonuniform dispersion of gas bubbles

in a relatively small volume of liquid that contains

surface-active macromolecules, or surfactants

(agents that reduce the surface tension of

liquids). Foams have striking properties in that

they are neither solid, liquid, nor vapor, yet they

exhibit features of all three. Important uses for

customdesigned foams include detergents,

cosmetics, foods, fire extinguishing, oil recovery,

and many physical and chemical separation

techniques. Unintentional generation of foam, on

the other hand, is a common problem affecting

the efficiency and speed of a vast number of

industrial processes involving the mixing or

agitation of multicomponent liquids. It also

occurs in polluted natural waters and in the

treatment of wastewater. In all cases, control of

foam rheology and stability is required.

Examples of granular systems include soil and

polystyrene beads, which are often used as

packing material. Granular systems are made up

of a series of similar objects that can be as small

as a grain of sand or as large as a boulder.

Although granular systems are primarily

composed of solid particles, their behavior can be

fluid-like. The strength of a granular system is

based upon the friction between and geometric

interlocking of individual particles, but under

certain forces or stresses, such as those induced

by earthquakes, these systems exhibit fluidic

behavior.

Studying complex fluids in microgravity allows

for the analysis of fluid phenomena often masked

by the effects of gravity. For example, researchers

are particularly interested in the phase transitions

of colloids, such as when a liquid changes to a

solid. These transitions are easier to observe in

microgravity. Foams, which are particularly

sensitive to gravity, are more stable (and can

therefore be more closely studied for longer

periods of time) in microgravity. In magnetorheological fluids, controlling rheology induced by

a magnetic field has many potential applications,

from shock absorbers and clutch controls for cars

to robotic joint controls. Under the force
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

31

of Earth’s gravity, the magnetic particles in these

fluids often fall out of suspension due to

sedimentation, but in microgravity this problem is

eliminated. Investigations of the behavior of

granular systems, which have previously been

hampered by Earth’s gravity, are more feasible in

microgravity because they do not settle as they

do on Earth.

Multiphase Flow and Heat Transfer

This research area, which has applications in the

engineering of heat transfer systems and gas

purification systems, focuses on complex

problems of fluid flow in varying conditions.

Scientists are seeking to add to their currently

limited knowledge of how gravity-dependent

processes, such as boiling and steam

condensation, occur in microgravity. Boiling is

known to be an efficient way to transfer large

amounts of heat, and as such, it is often used for

cooling and for energy conversion systems. In

space applications, boiling is preferable to other

types of energy conversion systems because it is

efficient and the apparatus needed to generate

power is smaller.

Another of the mechanisms by which energy and

matter move through liquids and gases is

diffusive transport. The way atoms and molecules

diffuse, or move slowly, through a liquid or gas is

due primarily to differences in concentration or

temperature. Researchers use microgravity to

study diffusion in complex systems, a process

that would normally be eclipsed by the force of

gravity.

Understanding the physics of multiphase flow and

heat transfer will enable scientists to extend the

range of human capabilities in space and will

enhance the ability of engineers to solve problems

on Earth as well. Applications of this research

may include more effective air conditioning and

refrigeration systems and improvements in power

plants that could reduce the cost of generating

electricity.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

32

Interfacial Phenomena

Research in this area focuses on how an

interface, like the boundary between a solid and a

liquid, acquires and maintains its shape. Interface

dynamics relate to the interaction of surfaces in

response to heating, cooling, and chemical

influences. A better understanding of this topic

will contribute to improved materials processing

and other applications.

Interfacial phenomena, such as the wetting and

spreading of two immiscible liquids or the

spreading of fluid across a solid surface, are

ubiquitous in nature and technology. Duck

feathers and waterproof tents repel water because

the wetting properties of the surfaces of their

fibers prevent water from displacing the air in the

gaps between the fibers. In contrast, water

spontaneously displaces air in the gaps of a

sponge or filter paper. Technologies that rely on

dousing surfaces with fluids like agricultural

insecticides, lubricants, or paints depend on the

wetting behavior of liquids and solids. Wetting is

also a dominant factor in materials processing

techniques, including film and spray coating,

liquid injection from an orifice, and crystal

growth. Interfaces dominate the properties and

behavior of advanced composite materials, where

wetting of the constituent materials dictates the

processing of such materials. Understanding and

controlling wetting and spreading pose both

scientific and technological challenges.

In reduced gravity, wetting determines the

configuration and location of fluid interfaces, thus

greatly influencing, if not dominating, the

behavior of multiphase fluid systems. This

environment provides scientists with an excellent

opportunity to study wetting and surface tension

forces that are normally masked by the force of

Earth’s gravity. This research also provides

information that can help improve the design of

space engineering systems strongly affected by

wetting, including liquid-fuel supply tanks, two-phase

heat transfer and/or storage loops, and fluids

management devices for life support purposes.

Comparison of thermocapillary flows on Earth (top) and in

micogravity (bottom). The flow pattern (indicated by the white

areas) in the Earth-based experiments is only evident on the fluid’s

surface, while the flow pattern in microgravity encompasses the

entire fluid.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

33

Dynamics and Stability

This broad area of research includes drop

dynamics, capillarity, and magneto/electrohydrodynamics.

Drop dynamics research deals with the behavior

of liquid drops and gas bubbles under the

influence of external forces and chemical effects.

Research in drop dynamics ranges from the study

of rain in the atmosphere to the investigation of

chemical processes. A potential application of

these studies is in the realm of materials

processing. In forming solid materials from

liquids in space, it is usually important to create

pure and/or uniform solids—gas bubbles and

drops of foreign liquids are undesirable. Yet due

to the microgravity environment, these bubbles

and drops of substances of lower densities would

not “rise to the top” the way they would if they

were on the ground, which makes extraction of

the bubbles difficult. Researchers are attempting

to resolve this problem in order to facilitate better

materials processing in space.

Scientists are also interested in studying single

bubbles and drops as models for other natural

systems. The perfect spheres formed by bubbles

and drops in microgravity (due to the dominance

of surface tension forces) are an easy fit to

theoretical models of behavior—fewer

adjustments need to be made for the shape of the

model. Investigators can manipulate the spherical

drops using sound and other impulses, creating

an interactive model for processes such as atom

fissioning.

Capillarity refers to a class of effects that depend

on surface tension. The shape a liquid assumes in

a liquid-liquid or liquid-gas system is controlled

by surface tension forces at the interface. Small

disturbances in the balance of molecular energies

at these boundaries or within the bulk of the liquid

can cause shifts in the liquid’s position and shape

within a container (such as a fuel tank) or in a

containing material (such as soil). These changes,

or capillary effects, often occur in liquids on Earth,

This sequential photo shows a liquid bridge undergoing a

series of shape changes. Liquid bridge investigations on the

Shuttle have tested theories of electrohydrodynamics.

In materials science research, float 20ne samples are

sometimes usedfor crystal growth. For a 87oat-zone

sampler the surface tension of the melt keeps the sample

suspended between two sample rods in afurnace. A

thorough understanding of the capillarity and surface

tension effects in a molten sample allows better

experiment control and results prediction.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

34

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Unifying Concepts and Processes

Joule heating occurs when electric current flows through a

material. This is how an electric toaster works .

Researchers observe thefloat package and data rack of a superfluid

helium experiment on a parabolic aircraft fight.

but are to some degree masked or minimized by

the stronger force of gravity. In microgravity,

however, capillary effects become prominent. The

study of capillary phenomena in microgravity will

enable researchers to better understand and

predict fluid configurational changes both on

Earth and in low-gravity environments.

Microgravity fluid physics researchers also study

the effects of magnetic and electric fields on fluid

flows, or magneto/electrohydrodynamics.

Promising microgravity research subjects in this

area include weak fluid flows, such as those

found in poorly conducting fluids in a magnetic

field, and Joule heating. In Earth’s gravity, Joule

heating causes buoyancy-driven flows which, in

turn, obscure its effects. In microgravity, however,

buoyancy-driven flows are nearly eliminated, so

researchers are not only able to study the effects

of Joule heating, but they can also observe other

processes involving applied electric fields, such

as electrophoresis.

Fundamental Physics

Physics is a major part of fundamental science

where the ultimate goal is to establish a unified

description of the basic laws that govern our

world. At present fundamental physics includes

low temperature physics, condensed matter

physics (the study of solids and liquids), laser

cooling and atomic physics, and gravitational and

relativistic physics. A unifying characteristic of

these research areas is that they address

fundamental issues which transcend the

boundaries of a particular field of science.

The majority of experiments in fundamental

physics are extensions of investigations in

Earthbased laboratories. The microgravity

experiment in these cases presents an

opportunity to extend a set of measurements

beyond what can be done on Earth, often by

several orders of magnitude. This extension can

lead either to a more precise confirmation of our

previous understanding of a problem,
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

35

or it can yield fundamentally new insight or

discovery. The remainder of fundamental physics

research involves tests of the fundamental laws

which govern our universe. Investigations aim at

enhancing our understanding of the most basic

aspects of physical laws, and as such may well

have the most profound and lasting longrange

impact on mankind’s existence on Earth and in

space.

There are many examples of how fundamental

science has had an impact on the average person.

Basic research in condensed matter physics to

explain the behavior of semiconductors led to the

development of transistors which are now used in

communication devices, and which produce ever

more prevalent and capable computer technology.

Research in low temperature physics to explore

the properties of fluids at very low temperatures

led to advanced magnetic resonance techniques

that have brought extremely detailed magnetic

resonance imaging to the medical doctor, so

today much exploratory surgery can be avoided.

A less widely appreciated part played by

fundamental science in today’s world has been

the need to communicate large quantities of data

from physics experiments to collaborators at

many locations around the world. Satisfying this

need was instrumental in the development of the

Internet and the World Wide Web.

Fundamental physics research benefits from both

the reduction in gravity’s effects in Earth-orbit and

from the use of gravity as a variable parameter. In

condensed matter physics, the physics of critical

points has been studied under microgravity

conditions. This field needs microgravity because

the ability to approach a critical point in the

Earthbound laboratory is limited by the uniformity

of the sample which is spoiled by hydrostatic

pressure variations. One of the important issues

in condensed matter physics is the nature of the

interface between solids and fluids. The boundary

conditions at this interface have an influence on

macroscopic phenomena, including wetting. The

microscopic aspects of the system near the

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Unifying Concepts and Processes

The critical point is the temperature at which the differences

between liquids and gases disappear. Above that temperature, the

liquid smoothly transforms to the gaseous state; boiling

disappears.

Mathematics Standards

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Communication

∆ ❏ Mathematics as Problem Solving

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Unifying Concepts and Processes

Hydrostatic pressure is the result of lhe weighl of a material

above the point of measurement.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

36

Mathematics Standards

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Communication

∆ ❏ Mathematics as Problem Solving

∆ ❏ Measurement

Science Standards

∆ ❏ History and Nature of Science

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Science as Inquiry

∆ ❏ Unifying Concepts and Processes

There are three temperature scales commonly used in the world.

The Kelvin scale, the Celsius temperature scale, and the

Fahrenheit scale. The SI unit for temperature is the Kelvin. In

most scientific laboratories, temperatures are measured and

recorded in Kelvin’s or degrees Celsius. The Celsius scale is used

for weather reporting in most of the world. The United States and

some other countries use the Fahrenheit scale for weather

reporting.

The Kelvin scale is defined around the triple point of water (solid

ice, liquid water, and water vapor coexist in thermal equilibrium)

which is assigned the temperature 273.16 K. This is equal to

0.01°C and 32.02°F. Absolute zero, the coldest anything can get,

is 0 K, -273.15°C, and -459.67°F.

Questions for Discussion

• How do you convert between these different temperature

scales?

• What are the boiling and freezing points of water on all these

scales, at 1 atm pressure?

boundary are difficult to study. However, when the

fluid is near a critical point, the boundary layer

adjacent to the solid surface acquires a

macroscopic thickness. Research under

microgravity conditions permits the study of not

only the influence of the boundaries on

thermodynamic properties, but also transport

properties such as heat and mass transport. One

of the most dramatic advancements in atomic

physics over the last decade has been the

demonstration that laser light can be used to cool

a dilute atomic sample to within micro- or even

nano-degrees of absolute zero. At these low

temperatures, the mean velocity of the atoms

drops from several hundred m/s to cm/s or mm/

s, a reduction by four to five orders of magnitude.

When atoms are moving this slowly,

measurements of atomic properties can be made

more precisely because the atoms stay in a given

point in space for a longer time. In this regime,

the effects of gravity dominate atomic motion so

experiments performed in a microgravity

environment would allow even more precise

measurements.

Among the most important goals of such

research is the improvement of ultra-high

precision clocks. These clocks not only provide

the standard by which we tell time, but are crucial

to the way we communicate and navigate on

Earth, in the air, and in space. Laser cooled atoms

have significantly improved the accuracy and

precision of clocks because these atoms move

very slowly and they remain in a given

observation volume for very long times. However,

observation times in these clocks are still affected

by gravity. Because of the effects of gravity, the

atoms used in these clocks ultimately fall out of

the observation region due to their own weight.

Increased observation times are possible in

microgravity and can result in further

improvements in precision of at least one or two

orders of magnitude.

Indeed, clocks are central to the study of general

relativity and in questions concerning the very

nature of gravity itself. The motivation for space
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

37

based clocks is not only tied to the improved

performance expected in a microgravity

environment but also these clocks will have

access to different positions in space than are

available on Earth. An important example of this

physics is revealed in the comparison of an Earthbased clock with a space-based clock. This

comparison provides a direct measurement of the

gravitational redshift. Tests of Einstein’s theories

of relativity and of other theories of gravitation

serve as a foundation for understanding how

matter and space-time itself behave at large

length scales and under extreme conditions. The

freefall environment of orbit, the use of low

temperature techniques, and the use of high

precision frequency standards offer opportunities

to perform improved tests of these theories.

Direct tests of gravitation theories and other

fundamental theories, including the Law of

Universal Gravitation, can be performed in a

microgravity environment.

Materials Science

Materials science is an extremely broad field that

encompasses the study of all materials. Materials

scientists seek to understand the formation,

structure, and properties of materials on various

scales, ranging from the atomic to microscopic to

macroscopic (large enough to be visible).

Establishing quantitative and predictive

relationships between the way a material is

produced (processing), its structure (how the

atoms are arranged), and its properties is

fundamental to the study of materials.

Materials exist in two forms: solids and fluids.

Solids can be subdivided into two categorie—-

crystalline and noncrystalline (amorphous)—

based on the internal arrangement of their atoms

or molecules. Metals (such as copper, steel and

lead), ceramics (such as aluminum oxide and

magnesium oxide), and semiconductors (such as

silicon and gallium arsenide) are all crystalline

solids because their atoms form an ordered

Many materials scientists use a triangle such as this to

describe the relationship between structure, processing,

and properties. Microgravity can play an important role

in establishing the relationships in a quantitative and

predictive manner.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

38

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Unifying Concepts and Processes

A semiconductor is a substance, such as germanium and silicon,

that is a poor electrical conductor at room temperature but is

improved by minute additions of certain substances (dopants) or

by the application of heat, light, or voltage; a material with a

forbidden energy gap less than 3 eV.

Schematic of the Electromagnetic Containerless Processing Facility

(TEMPUS) used on Shuttle missions STS-65 and STS-83.

internal structure. Most polymers (such as

plastics) and glasses are amorphous solids,

which means that they have no long range

specifically ordered atomic or molecular

arrangement.

One principal objective of microgravity materials

science research is to gain a better understanding

of how gravity-driven phenomena affect the

solidification and crystal growth of materials.

Buoyancy-driven convection, sedimentation, and

hydrostatic pressure can create defects

(irregularities) in the internal structure of

materials, which in turn alter their properties.

The virtual absence of gravity-dependent

phenomena in microgravity allows researchers to

study underlying events that are normally

obscured by the effects of gravity and which are

therefore difficult or impossible to study

quantitatively on Earth. For example, in

microgravity, where buoyancy-driven convection

is greatly reduced, scientists can carefully and

quantitatively study segregation, a phenomenon

that influences the distribution of a solid’s

components as it forms from a liquid or gas.

Microgravity also supports an alternative

approach to studying materials called

containerless processing. Containerless

processing has an advantage over normal

processing in that containers can contaminate the

materials being processed inside them. In

addition, there are some cases in which there are

no containers that will withstand the very high

temperatures and corrosive environments needed

to work with certain materials. Containerless

processing, in which acoustic, electromagnetic,

or electrostatic forces are used to position and

manipulate a sample, thereby eliminating the need

for a container, is an attractive solution to these

problems.

Furthermore, microgravity requires much smaller

forces to control the position of containerless

samples, so the materials being studied are not
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

39

disturbed as much as they would be if they were

levitated on Earth.

Materials science research in microgravity leads

to a better understanding of how materials are

formed and how the properties of materials are

influenced by their formation. Researchers are

particularly interested in increasing their

fundamental knowledge of the physics and

chemistry of phase changes (when a material

changes from liquid to solid, gas to solid, etc.).

This knowledge is applied to designing better

process-control strategies and production

facilities in laboratories on Earth. In addition,

microgravity experimentation will eventually

enable the production of limited quantities of

high-quality materials and of materials that exhibit

unique properties for use as benchmarks.

Microgravity researchers are interested in

studying various methods of crystallization,

including solidification (like freezing water to

make ice cubes), crystallization from solution (the

way rock candy is made from a solution of sugar

and water), and crystal growth from the vapor

(like frost forming in a freezer). These processes

all involve fluids, which are the materials that are

most influenced by gravitational effects.

Examining these methods of transforming liquids

or gases into a solid in microgravity gives

researchers insight into other influential

processes at work in the crystallization process.

Electronic Materials

 Electronic materials play an important role in the

operation of computers, medical instruments,

power systems, and communications systems.

Semiconductors are well-known examples of

electronic materials and are a main target of

microgravity materials science research.

Applications include creating crystals for use in

X-ray, gamma-ray, and infrared detectors, lasers,

computer chips, and solar cells. Each of these

devices epends on the ability to manipulate the

crystalline and chemical structure (perfection) of

Schematic diagram of a multizone furnace used to grow

semiconductor materials on the Shuttle. A mechanism moves an

existing c crystal through the temperature zones, melting the

sample then cooling it so that it solidifies. In other furnace

designs, the heating mechanism moves and the sample is

stationary. What are the advantages and disadvantages of each

approach?
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

40

Mathematics Standards

∆ ❏ Mathematical Connections

∆ Patterns and Functions

∆ Geometry

❏ Geometry from a Synthetic Perspective

Science Standards

∆ ❏ Earth and Space Science

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Unifying Concepts and Processes

Questions for Discussion

• What is an ordinary drinking glass made from?

• What different things are added to glass to change its

properties?

• What natural processes produce glasses?

• What are the differences between how glasses and crystalline

solids fracture?

the material, which can be strongly influenced by

gravity as crystals are formed.

The properties of electronic materials are directly

related to the degree of chemical and crystalline

perfection present in the materials. However,

perfect crystals are not normally the ultimate

goal. For example, the presence of just a few

impurities in some electronic materials can

change their ability to conduct electricity by over

a million times. By carefully controlling crystalline

defects and the introduction of desirable

impurities to the crystals, scientists and

engineers can design better electronic devices

with a wide range of applications.

Glasses and Ceramics

A glass is any material that is formed without a

long range ordered arrangement of atoms. Some

materials that usually take crystalline forms, like

metals, can also be forced to form as glasses by

rapidly cooling molten materials to a temperature

far below their normal solidification point. When

the material solidifies, it freezes so quickly that its

atoms or molecules do not have time to arrange

themselves systematically.

Ceramics are inorganic nonmetallic materials that

can be extraordinarily strong at very high

temperatures, performing far better than metallic

systems under certain circumstances. They will

have many more applications when important

fundamental problems can be solved. If a ceramic

turbine blade, for example, could operate at high

temperatures while maintaining its strength, it

would provide overall thermodynamic efficiencies

and fuel efficiencies that would revolutionize

transportation. The problem with ceramics is that

when they fail, they fail catastrophically, breaking

in an irreparable manner.

Glasses and ceramics are generally unable to

absorb the impacts that metals can; instead, they

crack under great force or stress (whereas metals

generally bend before they break). An important

part of ceramics and glass research in

Schematic of silicon dioxide tetrahedra. The top

view is of a crystalline ordered structure. The

bottom view is of a disordered glassy solid.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

41

microgravity involves controlling the minute flaws

that govern how these materials fail. From

information obtained through microgravity

research, scientists hope to be able to control the

processing of ceramics so that they can, during

processing, prevent the formation of

imperfections that lead to catastrophic failure.

Applications for knowledge obtained through

research in these areas include improving glass

fibers used in telecommunications and creating

high-strength, abrasion-resistant crystalline

ceramics used for gas turbines, fuel-efficient

internal combustion engines, and bioceramic

artificial bones, joints, and teeth.

Metals and Alloys

Metals and alloys constitute an important

category of engineered materials. These materials

include structural materials, many types of

composites, electrical conductors, and magnetic

materials. Research in this area is primarily

concerned with advancing the understanding of

metals and alloys processing so that structure

and, ultimately, properties, can be controlled as

the materials are originally formed. By removing

the influence of gravity, scientists can more

closely observe influential processes in structure

formation that occurs during solidification. The

properties of metals and alloys are linked to their

crystalline and chemical structure; for example,

the mechanical strength and corrosion resistance

of an alloy are determined by its internal

arrangement of atoms, which develops as the

metal or alloy solidifies from its molten state.

One aspect of the solidification of metals and

alloys that influences their microstructures is the

shape of the boundary, or interface, that exists

between a liquid and a solid in a solidifying

material. During the solidification process, as the

rate of solidification increases under the same

thermal conditions, the shape of the solidifying

interface has been shown to go through a series

of transitions. At low rates of growths the

interface is planar (flat or smoothly curved

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Unifying Concepts and Processes

An alloy is a combination of two or more metals.

Magnification of a sample of an aluminum-indium alloy. When

the sample is melted then controllably solidifies in the AGHF; the

indium forms in cylindrica lfibers within a solid aluminum

matrix.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

42

Mathematics Standards

∆ Geometry

❏ Geometry from an Algebraic Perspective

❏ Geometry from a Synthetic Perspective

∆ ❏ Mathematical Connections

∆ ❏ Mathematics as Communication

Science Standards

∆ ❏ Physical Science

∆ ❏ Unifying Concepts and Processes

One of the important characteristics of a solid is its shape. On a

visible scale, the function of some solids may depend on the

ability to sit in a stable manner on a surface or to fit tightly into

some configuration. On a smaller scale, the structures of

crystalline solids are defined by the ordered placement of atoms.

The basis of understanding crystalline structure and the shapes of

solids is a knowledge of the definitions of two-dimensional

shapes (polygons) and three-dimensional solids (polyhedra).

A simple k-sided polygon is defined by connecting k points in a

plane with line segments such that no edges intersect except at

the defining points (vertices). The sum of the angles in any

polygon equals 2x(k-2)x90°. Specific names given to some

simple polygons are given below.

Name # of Sides (k)

triangle 3

quadrilateral 4

pentagon 5

hexagon 6

heptagon 7

octagon 8

nonagon 9

decagon 10

undecagon 11

dodecagon 12

Regular polygons are those for which all the sides are the same

length and all the angles are the same. The angles of a regular

polygon are defined by θ=(k-2)x 180°/k.

Questions for Discussion

• Discuss special cases of triangles and quadrilaterals such as

isosceles triangles, parallelograms, trapezoids.

• What is the common name for a regular triangle? For a regular

quadrilateral?

• Is there a general equation for the area of any polygon’?

on a macroscopic scale). As the rate of growth

increases, the interface develops a corrugated

texture until three dimensional cells (similar in

shape to the cells in a beehive but much smaller)

form in the solid. A further increase in the rate of

growth causes the formation of dendrites. The

development of these different interface shapes

and the transition from one shape to another is

controlled by the morphological stability (shape

stability) of the interface. This stability is

influenced by many factors. Gravity plays an

important role in a number of them. In particular,

buoyancy-driven convection can influence the

stability and, thus, the shape of the solidifying

interface. Data obtained about the conditions

under which certain types of solidification

boundaries appear can help to explain the

formation of the crystalline structure of a

material.

Another area of interest in metals and alloys

research in microgravity is multiphase

solidification. Certain materials, which are known

as eutectics and monotectics, transform from a

single phase liquid to substances of more than

one phase when they are solidified. When these

materials are processed on Earth, the resultant

substances have a structure that was influenced

by gravity either due to buoyancy-driven

convection or sedimentation. But when processed

in microgravity, theory predicts that the end

product should consist of an evenly dispersed,

multiphase structure.

Eutectic solidification is when one liquid, of

uniform composition, forms with two distinct

solid phases. An example of such a material is the

alloy manganese-bismuth. Solidifying liquid MnBi results in two different solids, each of which

has a chemical composition that differs from the

liquid. One solid (the minor phase) is distributed

as rods, particles, or layers throughout the other

solid (a continuous matrix, or major phase).

Monotectics are similar to eutectics, except that a

monotectic liquid solidifies to form a solid and a
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

43

liquid (both of which are different in composition

from the original liquid). Al-In is a monotectic that

starts out as indium dissolved completely in

aluminum, but when the alloy is solidified under

the appropriate conditions, it forms a solid

aluminum matrix with long thin “rods” of liquid

indium inside it. As the system cools, the rods of

liquid indium freeze into solid rods. The indium

rods are dispersed within the structure of the

solidified material.

Polymers

Polymers are macromolecules (very large

molecules) made up of numerous small repeating

molecular units called monomers. They appear

naturally in wool, silk, and rubber and are

manufactured as acrylic, nylon, polyester, and

plastic. Polymers are typically composed of long

chains of monomers, appearing on the molecular

scale as if they had a spine of particular elements

such as carbon and nitrogen. The bonding

between individual polymer molecules affects the

material’s physical properties such as surface

tension, miscibility, and solubility. Manipulation of

these bonds under microgravity conditions may

lead to the development of processes to produce

polymers with more uniform and controlled

specific properties. Important optoelectronic and

photonic applications are emerging for polymers,

and many of the properties needed are affected by

the polymers’ crystallinity. This crystallinity,

which is the extent to which chains of molecules

line up with each other when the polymer is

formed, may be more easily understood and

controlled when removed from the influence of

gravity.

Growing polymer crystals is more difficult than

growing inorganic crystals (such as metals and

alloys) because the individual polymer molecules

weigh more and are more structurally complex,

which hinders their ability to attach to a growing

crystal in the correct position. Yet in microgravity,

the process of polymer crystal growth can be

studied in a fundamental way, with special

attention to the effects of such variables as

Regular polyhedra (or the Platonic Solids) are listed and shown

below.

Name Formed By

tetrahedron 4 triangles

cube 6 squares

octahedron 8 triangles

dodecahedron 12 pentagons

icosahedron 20 triangles

The Five Regular Polyhedra or Platonic Solids Tnp-Tetrahedron;

second row left-Cube: second row right- Octahedron; third row

left-Dodecahedron; third row right-Icosahedron.

Questions for Discussion

• What do you think of as a cylinder and cone?

• What are the general definitions cylinder and cone’?

• What shapes are some mineral samples you have in your

classroom?

• Investigate the crystalline structure of halite (rock salt),

fluorine, quartz, diamond, iron.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

44

NASA’s Enterprise for the Human

Exploration and Development of Space

The goals of this Enterprise are to

• Increase human knowledge of nature’s processes using the

space environment,

• Explore and settle the Solar System,

• Achieve routine space travel,

• Enrich life on Earth through people living and working in

space.

Microgravity research will contribute to the areas of cryogenic

fuel management, spacecraft systems, in-situ resource utilization,

power generation and storage, life support, fire safety, space

structures, and science exploration.

Elemental Percent Weight on Earth and Moon

Earth’s Crust Lunar Highland

Soils

O 47 45

 Fe 5 5

Si 28 21

Mg 2 4

Ca 4 11

Al 8 13

Na 3 0

K 3 0

temperature, compositional gradients, and the

size of individual polymer units on crystal growth.

In addition, just as microgravity enables the

growth of larger protein crystals, it may allow

researchers to grow single, large polymer crystals

for use in studying properties of polymers and

determining the effects of crystal defects on those

properties.

Microgravity Research and

Exploration

There is one endeavor for which microgravity

research is essential. That is the goal of exploring

new frontiers of space and using the Moon and

Mars as stepping stones on our journey. To

achieve these goals, we must design effective life

support systems, habitation structures, and

transportation vehicles. To come up with

workable designs, we must have a thorough

understanding of how the liquids and gases that

we need to sustain human, plant, and animal life

can be obtained, transported, and maintained; of

how structural materials can be formed in-situ

(on site); and of what types of fuels and fuel

delivery systems would allow us to get around

most efficiently. Microgravity research can

provide the insight needed to get us on our way.

The ability to use extraterrestrial resources is a

key element in the exploration of the solar

system. We believe that we can use the Moon as

a research base to develop and improve

processes for obtaining gases and water for

human life support and plant growth; for creating

building materials; and for producing propellants

and other products for transportation and power

generation. Oxygen extracted from lunar rocks

and soils will be used for life support and liquid

oxygen fuel. A byproduct of the extraction of

oxygen from lunar minerals may be metals and

semiconductors such as magnesium, iron, and

silicon. Metals produced on the Moon and

material mined from the surface will then be used

for construction of habitats, successive

processing plants, and solar cells.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

45

Current research in the areas of microgravity

science will guide our path as we develop the

means to use the Moon as a stepping stone to

Mars. Research into how granular materials

behave under reduced gravity conditions will be

important when we design equipment to mine and

move large amounts of lunar material. The ability

to extract gases and metals from minerals

requires an understanding of how gases, liquids,

and solids of different densities interact in lunar

gravity. Building blocks for habitats and other

structures can be made from the lunar regolith.

Research into sedimentation and sintering under

reduced gravity conditions will lead to appropriate

manufacturing procedures. Experiments have

already been performed on the Space Shuttle to

determine how concrete and mortar mixes and

cures in microgravity. An understanding of fluid

flow and combustion processes is vital for all the

materials and gas production facilities that will be

used on the Moon and beyond.

Science Standards

∆ ❏ Earth and Space Science

∆ ❏ Physical Science

Regolith is a layer of powder-like dust and loose rock that rests

on bedrock. In the case of the moon, fragmentation of surface

rocks by meteorite bombardment created much of the regolith

material.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

46

Skylab, America’s first space station.

Microgravity

Science Space

Flights

Until the mid-20th century, gravity was an

unavoidable aspect of research and technology.

During the latter half of the century, the use of

drop towers to reduce the effects of gravity

became more prevalent, although the extremely

short periods of time they provided (<6 seconds)

severely restricted the type of research that could

be performed.

Initial microgravity research centered around

solving space flight problems created by the

reduction in gravity’s effects experienced on orbit.

How do you get the proper amount of fuel to a

rocket engine in space or water to an astronaut on

a spacewalk? The brief periods of microgravity

available in drop towers at the Lewis Research

Center and the Marshall Space Flight Center were

sufficient to answer these basic questions and to

develop the pressurized systems and other new

technologies needed to cope with this new

environment. But, they still were not sufficient to

investigate the host of other questions that were

raised by having gravity as an experimental

variable.

The first long-term opportunities to explore

microgravity and conduct research relatively free

of the effects of gravity came during the latter

stages of NASA’s first great era of discovery. The

Apollo program presented scientists with the

chance to test ideas for using the space

environment for research in materials, fluid, and

life sciences. The current NASA microgravity

program had its beginning in experiments

conducted in the later flights of Apollo, the

Apollo-Soyuz Test Project, and onboard Skylab,

America’s first space station.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

47

Preliminary microgravity experiments conducted

during the 1970’s were severely constrained,

either by the relatively low power levels and space

available on the Apollo spacecraft, or by the low

number of flight opportunities provided to Skylab.

These experiments, as simple as they were,

provided new insights into the roles of fluid and

heat flows in materials processing Much of our

understanding of the physics underlying

semiconductor crystal growth, for example, can

be traced back to research initiated on Skylab.

Since the early 1980’s, NASA has sent crews and

payloads into orbit on board the Space Shuttle.

The Space Shuttle has given microgravity

scientists an opportunity to bring their

experiments to low-Earth orbit on a more regular

basis. The Shuttle introduced significant new

capabilities for microgravity research: larger,

scientifically trained crews; a major increase in

payload volume and mass and available power;

and the return to Earth of all instruments,

samples, and data. The Spacelab module,

developed for the Shuttle by the European Space

Agency, gives researchers a laboratory with

enough power and volume to conduct a limited

range of sophisticated microgravity experiments

in space.

Use of the Shuttle for microgravity research

began in 1982, on its third flight, and continues

today on many missions. In fact, most Shuttle

missions that aren’t dedicated to microgravity

research do carry microgravity experiments as

secondary payloads.

The Spacelab-1 mission was launched in

November 1983. The primary purpose of the

mission was to test the operations of the complex

Spacelab and its subsystems. The 71

microgravity experiments, conducted using

instruments from the European Space Agency,

produced many interesting and provocative

results. One investigator used the travelling heater

method to grow a crystal of gallium antimonide

doped with tellurium (a compound useful for

The Spacelab module in the Orbiter Cargo Bay.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

48

making electronic devices). Due to the absence of

gravity-driven convection, the space-grown

crystal had a far more uniform distribution of

tellurium than could be achieved on Earth. A

second investigator used molten tin to study

diffusion in low gravity- research that can

improve our understanding of the solidification of

molten metals.

Another Shuttle mission using the Spacelab

module was Spacelab-3, which flew in April 1985.

SL-3 was the first mission to include U.S.

developed microgravity research instruments in

the Spacelab. One of these instruments supported

an experiment to study the growth of crystals of

mercury iodide-a material of significant interest

for use as a sensitive detector of X-rays and

gamma rays. Grown at a high rate for a relatively

short time, the resulting crystal was as good as

the best crystal grown in the Earth-based

laboratory. Another U.S. experiment consisted of

a series of tests on fluid behavior using a

spherical test cell. The microgravity environment

allowed the researcher to use the test cell to

mimic the behavior of the atmosphere over a

large part of Earth’s surface. Results from this

experiment were used to improve mathematical

models of our atmosphere.

In October 1985, NASA launched a Spacelab

mission sponsored by the Federal Republic of

Germany, designated Spacelab-D1. American and

German scientists conducted experiments to

synthesize high quality semiconductor crystals

useful in infrared detectors and lasers. These

crystals had improved properties and were more

uniform in composition than their Earth-grown

counterparts. Researchers also successfully

measured critical properties of molten alloys.

The first Spacelab mission dedicated to United States microgravity

science on USML-I. The coast of Florida appears in the background.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

49

International Microgravity

Laboratory-1, January 1992

More than 220 scientists from the United States

and 14 other countries contributed to the

experiments flown on the first International

Microgravity Laboratory (IML-1) in January 1992.

Several biotechnology experiments concerned

with protein crystal growth enabled NASA

scientists to successfully test and compare two

different crystal-growing devices.

A German device called the Cryostat produced

superior-quality crystals of proteins from several

microorganisms including the satellite tobacco

mosaic virus (STMV), which has roles in diseases

affecting more than 150 crop plants. As a result

of this experiment, scientists now have a much

clearer understanding of the overall structure of

STMV. This information is useful in efforts to

develop strategies for combating viral damage to

crops.

IML-1 also carried experiments designed to probe

how microgravity affects the internal structure of

metal alloys as they solidify. The growth

characteristics, determined from one of the

experiments, matched the predictions of existing

models, providing experimental evidence that

current hypotheses about alloy formation are

correct.

United States Microgravity

Laboratory-1, June 1992

In June 1992 the first United States Microgravity

Laboratory (USML-1) flew aboard a 14-day

shuttle mission, the longest up to that time. This

Spacelab-based mission was an important step in

a long-term commitment to build a microgravity

program involving government, academic, and

industrial researchers.

The payload included 31 microgravity

experiments using some facilities and

instruments from previous flights, including the

Protein Crystal Growth facility, a Space

Payload Commander Bonnie J. Dunbar and Payload Specialist

Lawrence J. DeLucas working in the module on USML-1.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

50

Science Standards

∆ ❏ Earth and Space Science

∆ ❏ History and Nature Of Science

∆ ❏ Physical Science

∆ ❏ Unifying Concepts and Processes

Questions for Discussion

• What are Cd, Hg, Te, Zn?

• What do these elements have in common?

Hint: Look at their position on the periodic table of the elements.

Acceleration Measurement System, and the Solid

Surface Combustion Experiment. New experiment

facilities, all designed to be reusable on future

missions, included the Crystal Growth Furnace

(CGF), a Glovebox provided by the European

Space Agency, the Surface Tension Driven

Convection Experiment apparatus (STDCE), and

the Drop Physics Module.

Investigators used the CGF to grow crystals of

four different semiconductor materials at

temperatures as high as 1260°C. One spacegrown CdZnTe crystal developed far fewer

imperfections than even the best Earth-grown

crystals, results that far exceeded pre-flight

expectations. Thin crystals of HgCdTe grown from

the vapor phase had mirror-smooth surfaces even

at high magnifications. This type of surface was

not observed on Earth-grown crystals.

Researchers used the STDCE apparatus to explore

how internal movements of a liquid are created

when there are spatial differences in temperature

on the liquid’s surface. The results are in close

agreement with advanced theories and models

that the experiment researchers developed.

In the Drop Physics Module, sound waves were

used to position and manipulate liquid droplets.

Surface tension controlled the shape of the

droplets in ways that confirmed theoretical

predictions. The dynamics of rotating drops of

silicone oil also conformed to theoretical

predictions. Experimental and theoretical results

of this kind are significant because they illustrate

an important part of the scientific method:

hypotheses are formed and carefully planned

experiments are conducted to test them.

Sixteen different investigations run by NASA

researchers used the Glovebox, which provided a

safe enclosed working area; it also was equipped

with photographic equipment to provide a visual

record of investigation operations. The Glovebox

allowed crew members to perform protein

crystallization studies as they would on Earth,

including procedures that require

Fission sequence of a rotating levitated drop.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

51

hands-on manipulation. Among other results, use

of the Glovebox provided the best-ever crystals of

malic enzyme that may be useful in developing

anti-parasitic drugs.

The burning of small candles in the Glovebox

provided new insights into how flames can exist

in an environment in which there is no air flow.

The results were similar (though much longer

lived) to what can be seen by conducting similar

experiments in freefall here on Earth. (See Candle

Flames in Microgravity, in the Activities section of

this guide.) The candles burned for about 45 to

60 seconds in the Glovebox experiments.

Another Glovebox investigation tested how wire

insulation burns under different conditions,

including in perfectly still air (no air flow) and in

air flowing through the chamber from different

directions. This research has yielded extremely

important fundamental information and also has

practical applications, including methods for

further increasing fire safety aboard spacecraft.

The crew of scientist astronauts in the Spacelab

played an important role in maximizing the

science return from this mission. For instance,

they attached a flexible type of glovebox, which

provided an extra level of safety, to the Crystal

Growth Furnace. The furnace was then opened,

previously processed samples were removed and

an additional sample was inserted. This enabled

another three experiments to be conducted. Two

other unprocessed samples were already in the

furnace.

Spacelab-J,

September 1992

The Spacelab-J (SL-J) mission flew in September

1992. SL-J was the first Space Shuttle mission

shared by NASA and Japan’s National Space

Development Agency (NASDA). NASA

microgravity experiments focused on protein

crystal growth and collecting acceleration data in

support of the microgravity experiments.

Zeolite crystals can be grown in the Glovebox Facility. Shown

here are photos (at the same scale) of zeolite crystals grown on

USML-I (top) and on Earth (bottom).
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

52

NASDA’s science payload consisted of 22

experiments focused on materials science and

the behavior of fluids, and 12 human biology

experiments. NASDA also contributed two

experiment facilities. One of these, the Large

Isothermal Furnace, was used to explore how

various aspects of processing affect the

structure and properties of materials. The

second apparatus was a Free-Flow

Electrophoresis Unit used to separate different

types of molecules in a fluid.

United States Microgravity

Payload-1, October 1992

The first United States Microgravity Payload

(USMP-1) flew on a 10-day Space Shuttle

mission launched on October 22, 1992. The

mission was the first in an ongoing effort that

employs telescience to conduct experiments on

a carrier in the Space Shuttle Cargo Bay.

Telescience refers to how microgravity

experiments can be conducted by scientists on

the ground using remote control.

The carrier in the Cargo Bay consisted of two

Mission Peculiar Equipment Support Structures.

On-board, the two Space Acceleration

Measurement Systems measured how crew

movements, equipment operation, and thruster

firings affected the microgravity environment

during the experiments. This information was

relayed to scientists on the ground, who then

correlated it with incoming experiment data.

A high point of USMP-1 was the first flight of

MEPHISTO, a multi-mission collaboration

between NASA-supported scientists and French

researchers. MEPHISTO (designed and built by

the French Space Agency, Centre National

d’Etudes Spatiales or CNES) is designed to study

the solidification process of molten metals and

other substances. Three identical samples of one

alloy (a combination of tin and bismuth) were

solidified, melted, and resolidified more than 40

times, under slightly different conditions each

time. As each cycle ended, data were transmitted

USMP experiments are mounted on Mission Peculiar

Equipment Support Structures in the Shuttle Cay.rgo Bay.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

53

from the Space Shuttle to Marshall Space Flight

Center. There, researchers analyzed the

information in combination with data from the

Space Acceleration Measurement System and

sent back commands for adjustments. In all, the

investigators relayed more than 5000 commands

directly to their instruments on orbit. Researchers

compared experiment data with the predictions of

theoretical models and showed that mathematical

models can predict important aspects of the

experiment behavior. This first MEPHISTO effort

proved that telescience projects can be carried

out efficiently, with successful results.

The lambda point for liquid helium is the

combination of temperature and pressure at

which normal liquid helium changes to a

superfluid. On Earth, effects of gravity make it

virtually impossible to measure properties of

substances very close to this point. On USMP-1,

the Lambda Point Experiment cooled liquid

helium to an extremely low temperature—-a little

more than 2 K above absolute zero. Investigators

measured changes in its properties immediately

before it changed from a normal fluid to a

superfluid. Performing the test in microgravity

yielded temperature measurements accurate to

within a fraction of one billionth of a degree—

several hundred times more accurate than would

have been possible in normal gravity. Overall the

new data were five times more accurate than in

any previous experiment.

United States Microgravity

Payload-2, March 1994

The second United States Microgravity Payload

(USMP-2) flew aboard the Space Shuttle

Columbia for 14 days from March 4 to March 18,

1994. Building on the success of telescience in

USMP-1, the Shuttle Cargo Bay carried four

primary experiments which were controlled by

approximately 10,000 commands relayed by

scientists at Marshall Space Flight Center. USMP2 also included two Space Acceleration

Measurement Systems, which provided scientists

Science and mission management teams monitor and control

experiments from operations centers worldwide.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

54

Science Standards

∆ ❏ Physical Science

∆ ❏ Unifying Concepts and Processes

Dendrites are branching structures that develop as a molten

metal solidifies under certain conditions. The root of this word is

the (Greek dendron, meaning tree. Branching structures in

biology (nerve cells) and geology (drainage systems) are also

referred to as being dendritic.

on the ground with nearly instant feedback on

how various kinds of motion-including crew

exercise and vibrations from thruster enginesaffected mission experiments. The Orbital

Acceleration Research Experiment in the Cargo

Bay collected supplemental data on acceleration,

providing an indication of the quasi-steady

acceleration levels experienced by the

experiments.

Throughout the mission, the Critical Fluid Light

Scattering Experiment—-nicknamed Zeno—

analyzed the behavior of the element xenon as it

fluctuated between two different states, liquid and

gas. First, a chamber containing liquid xenon was

heated. Then, laser beams were passed through

the chamber as the xenon reached temperatures

near this transition point. A series of

measurements were taken of how the laser beams

were scattered (deflected) as the xenon shifted

from one state to another. Researchers expected

that performing the experiment on orbit would

provide more detailed information about how a

substance changes phase than could be obtained

on Earth. In fact, the results produced

observations more than 100 times more precise

than the best measurement on the ground.

The Isothermal Dendritic Growth Experiment

(IDGE) examined the solidification of a material

that is a well-established model for metals. This

material is especially useful as a model because it

is transparent, so a camera can actually record

what happens inside a sample as it freezes. In 59

experiments conducted during 9 days, over 100

television images of growing dendrites were sent

to the ground and examined by the research

team. Dendritic growth velocities and tip radii of

curvature were measured. Results obtained under

certain experiment conditions were not consistent

with current theory. This inconsistency was the

subject of subsequent research on USMP-3. In

another successful demonstration of telescience,

the team relayed more than 200 commands to the

IDGE, fine-tuning its operations.

A dendrite grown in the Isothermal Dendritic Growth

Experiment aboard the USMP-2. This is an example of how

most metals solidify.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

55

USMP-2 also included a MEPHISTO experiment.

On this mission, the MEPHISTO apparatus was

used for U.S. experiments to test how gravity

affects the formation of crystals from an alloy of

bismuth and tin that behaves much like a

semiconductor during crystal growth.

Metallurgical analysis of the samples has shown

that interactions between the molten and solid

alloy during crystallization play a key role in

controlling the final morphological stability of the

alloy.

Another USMP-2 materials science experiment

used the Advanced Automated Directional

Solidification Furnace (AADSF). An eleven day

experiment using the AADSF yielded a large, wellcontrolled sample of the alloy semiconductor,

HgCdTe. The results of various analysis

techniques performed on the crystal indicate that

variations in the acceleration environment had a

marked effect (due to changing residual fluid

flow) on the final distribution of the alloy’s

components in the crystal.

International Microgravity

Laboratory-2, July 1994

The second International Microgravity Laboratory

(IML-2), with a payload of 82 major experiments,

flew in July 1994 on the longest Space Shuttle

flight to that time. IML-2 truly was a world class

venture, representing the work of scientists from

the U.S. and 12 other countries.

Materials science experiments focused on various

types of metals processing. One was sintering, a

process that can combine different metals by

applying heat and pressure to them. A series of

three sintering experiments expanded the use in

space of the Japanese built Large Isothermal

Furnace, first flown on SL-J. It successfully

sintered alloys of nickel, iron, and tungsten.

Other experiments explored the capabilities of a

German-built facility called TEMPUS. It was

designed to position molten metal experiment

Representations of different .shapes of the liquid-solid interface in a

solidifying material: a) planar, b) cellular; and c) dendritic. More

information about interface morphology is provided in the Metals

and Alloys discussion in the Materials Science section of this

publication.

a

b

c
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

56

Mathematics Standards

❏ Conceptual Underpinnings of Calculus

❏ Functions

∆ ❏ Mathematical Connections

∆ Patterns and Functions

Science Standards

∆ ❏ Earth and Space Science

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Science in Personal and Social Perspectives

∆ ❏ Unifying Concepts and Processes

A gradient is the variation of a quantity such as temperature,

pressure, or concentration with respect to a given parameter,

typically distance. A temperature gradient can have dimensions

of temperature per length, for example, °C/cm.

samples (molten drops) away from the surfaces

of a container in order to eliminate processing

side effects of containers. Experiments of four

U.S. scientists were successfully completed, and

the research team developed improved

procedures for managing multi-user facilities.

One of the experiments used a clever approach to

measure two important thermophysical properties

of molten metals. While a spherical drop of

molten metal was positioned in a containerless

manner it was momentarily distorted by using

electromagnetic forces to squeeze it. When the

squeezing was released, the droplet began to

oscillate. The surface tension of the molten metal

was determined from the frequency of the

oscillation. The oscillation gradually decayed. The

rate at which the decay occurred was used to

determine the viscosity of the molten material.

Biotechnology experiments were performed using

the Advanced Protein Crystallization Facility,

developed by the European Space Agency. The

facility’s 48 growth chambers operated

unattended throughout the flight, producing highquality crystals of nine proteins. High-resolution

video cameras monitored critical crystal growth

experiments, providing the research team with a

visual record of the processes. U.S. investigators

used the Bubble, Drop, and Particle Unit to study

how temperature gradients in the liquids

influence the movement and shape of gas bubbles

and liquid drops. The Critical Point Facility

enabled researchers to study how a fluid behaves

at its critical point. Research using the Critical

Point Facility is applicable to a broad range of

scientific questions, including how various

characteristics of solids change under different

experimental conditions.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

57

Force of

Earth's

Gravity

Earth Environment

Experimental

Sphere

Microgravity Environment

Force of

Radial

Experimental Gravity

Sphere

Gravitational force acting on spherical planetary

models on Earth and in a microgravity environment

United States Microgravity

Laboratory-2, October 1995

The second United States Microgravity

Laboratory (USML-2) launched on October 20,

1995 for a mission with more than 16 days on

orbit. During that time microgravity research was

conducted around-the-clock in the areas of

biotechnology, combustion science, fluid physics,

and materials science. It was a perfect example of

interactive science in a unique laboratory

environment.

Along with investigations that previously flew on

USML-1, several additional experiment facilities

flew on USML-2. Fourteen protein crystal growth

experiments in the Advanced Protein

Crystallization Facility had varied results that

provided more insight into the structures of some

of the proteins and into optimal experiment

conditions. The goal of the Geophysical Fluid Flow

Cell experiment was to study how fluids move in

microgravity as a means of understanding fluid

flow in oceans, atmospheres, planets, and stars.

The results of the studies of fluid movement and

velocity are still being analyzed.

Four separate studies were performed in the

Crystal Growth Furnace (CGF). The goals of the

experiments were to investigate quantitatively the

gravitational influences on the growth and quality

of the compound semiconductor, CdZnTe, using

the seeded, modified Bridgman-Stockbarger

crystal growth technique; to investigate

techniques for uniformly distributing a dopant,

selenium, during the growth of GaAs crystals; to

understand the initial phase of the process of

vapor crystal growth of complex, alloy-type

semiconductors (HgCdTe); and to test the

integration of a current induced interface

demarcation capability into the CGF system and to

assess the influences of a change in Shuttle

attitude on a steady-state growth system using

the demonstrated capabilities of the interface

demarcation technique.

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Science in Personal and Social Perspectives

∆ ❏ Unifying Concepts and Processes

A dopant is an impurity intentionally added to a pure

semiconductor to alter its electronic or optical properties.

Earth Environment Microgravity Environment

Force of

Earth’s

Gravity

Experimental

Sphere

Force of

Radial

Gravity Experimental

Sphere

Gravitational force acting on spherical planetary

models on Earth and in a microgravity environment

In the Geophysical Fluid Flow Cell, electric charges,

electrostatic force, and heaters are used to simulate

buoyancy forces, radial gravity, and heating patterns

in planetary atmospheres. As shown in the diagram,

attempts to use spherical models on Earth are

hampered by the force of Earth’s gravity acting

perpendicular to the sphere’s rotation (indicated by

the large curving arrow around the sphere’s equator).

In microgravity, this problem is removed.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

58

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Science in Personal and Social Perspectives

∆ ❏ Unifying Concepts and Processes

A surfactant is a substance added to a liquid to change its

surface tension. Surfactants are used in experiments where a

liquid must wet its container in a particular way. A common use

of surfactants is dishwashing detergent. The surfactant properties

of the detergent is what causes food grease and oil to separate

from most household dishware.

Two investigators had experiments conducted in

the Drop Physics Module. The Science and

Technology of Surface-Controlled Phenomena

Experiments had three major goals: to determine

the surface properties of liquids in the presence

of surfactants; to investigate the dynamic

behavior and the coalescence of droplets coated

with surfactant materials; and to study the

interactions between droplets and acoustic

waves. The shapes of oscillating drops recorded

on videotape were analyzed frame by frame,

revealing the variations of the oscillation

amplitude with time. The frequency and damping

constant of the droplet shape oscillations were

calculated. Analysis of the results is ongoing.

The goals of the Drop Dynamics Experiment were

to gather high-quality data on the dynamics of

liquid drops in microgravity for comparison with

theoretical predictions and to provide scientific

and technical information needed for the

development of new fields, such as containerless

processing of materials and polymer

encapsulation of living cells. The experiments on

the USML-2 mission included breaking one drop

into two drops (bifurcation) and positioning a

drop of one liquid at the center of a drop of a

different liquid. Preliminary results show that the

acoustic levitation technique has a strong

influence on the drop bifurcation process.

Seven investigations were performed in the

Glovebox on USML-2. These studies examined

various aspects of fluid behavior, combustion,

and crystal growth. Two separate devices were

used for protein crystal growth experiments.

The Surface Tension Driven Convection

Experiment investigated the basic fluid mechanics

and heat transfer of thermocapillary flows

generated by temperature variations along free

surfaces of liquids in microgravity. It determined

when and how oscillating flows were created.

Preliminary analysis indicates that current

theoretical models used to predict the onset of

oscillations are consistent with the experiment

results.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

59

The USML-2 Zeolite Crystal Growth experiment

attempted to establish a quantitative

understanding of zeolite crystallization to allow

control of both crystal defect concentration and

crystallite size. The preliminary conclusions

indicate that, with few exceptions, the crystals

from USML-2 are larger in size than their Earthgrown counterparts and are twice as large as

those grown on previous Shuttle flights. Analysis

will continue to determine the effect of space

processing on crystal defect concentration.

The projects that measured the microgravity

environment added to the success of the mission

by providing a complete picture of the Shuttle’s

environment and its disturbances. The Orbital

Acceleration Research Experiment (OARE)

provided real-time quasi-steady acceleration data

to the science teams. The Microgravity Analysis

Workstation (MAWS) operated closely with the

OARE instrument, comparing the environment

models produced by the MAWS with the actual

data gathered by the OARE. Two other

instruments, the Space Acceleration

Measurement System and the Three Dimensional

Microgravity Accelerometer, took g-jitter

measurements throughout the mission. The

Suppression of Transient Events by Levitation

demonstrated a vibration isolation technology that

may be suitable for experiments that are sensitive

to variations in the microgravity environment.

United States Microgravity

Payload-3,

February 1996

The third United States Microgravity Payload

mission launched on February 22 for 16 days of

research on orbit. During that time, microgravity

research was conducted in the areas of

combustion science, fluid physics, and materials

science. The ultimate benefit of USMP-3 research

will be improvements in products manufactured

on Earth. During the eight and one-half days

dedicated to microgravity science, researchers

used telescience to control materials processing

and thermodynamic experiments in the Cargo Bay

Science Standards

∆ ❏ Physical Science

∆ ❏ Science and Technology

∆ ❏ Scienee in Personal and Social Perspectives

∆ ❏ Unifying Concepts and Processes

Zeolites are hydrous aluminum silicate minerals which also

contain cations of sodium, potassium, calcium, strontium,

barium, or a synthetic compound. They are commonly used as

molecular filters. For example, they are used to make every drop

of gasoline sold in the United States.

The change in acceleration character seen in the middle of this

plot is due to a crew member swinging an experiment container

around to mix its contents. Examination of the plot indicates that

the crew member swung his arm around seven to eight times in

ten seconds.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

60

Vibration Frequencies Commonly Seen in

Orbiter Accelerometer Data

Freq. (Hz) Disturbance Source

0.43 cargo bay doors

3.5 Orbiter fuselage torsion

3.66 structural frequency of Orbiter

4.64 structural frequency of Orbiter

5.2 Orbiter fuselage normal bending

7.4 Orbiter fuselage lateral bending

17 Ku band antenna dither

20 experiment air circulation fan

22 refrigerator freezer compressor

38 experiment air circulation fan

39.8 experiment centrifuge rotation speed

43 experiment air circulation fan

48 experiment air circulation fan

53 experiment air circulation fan

60 refrigerator piston compressor

80 experiment water pump

166.7 Orbiter hydraulic circulation pump

and astronauts performed combustion studies in

 the Middeck Glovebox.

 The MEPHISTO science team used flight-proven

equipment to learn how the chemical composition

of solidifying Sn-Bi alloys changes, and can be

controlled, during solidification. Such knowledge

applies to ground-based materials processing.

For the first time, the changes in the microgravity

environment caused by carefully planned Shuttle

thruster firings were correlated with the effects of

fluid flows in a growing crystal. With the help of

data from the Space Acceleration Measurement

System, the experiment data showed that with

thruster accelerations parallel to the crystal-melt

interface a large effect was noted, whereas when

thruster accelerations were perpendicular to the

interface there was little impact. Also, the

MEPHISTO team successfully monitored the point

at which their sample’s crystal interface

underwent a key change-from flat to cellular (like

three dimensional ripples)-as it solidified.

Measurements from the MEPHISTO facility will

now be analyzed, along with the final metallic

samples, in order to increase our understanding

of subtle changes that occurred during the

samples’ solidification and subsequent cooling.

In the Advanced Automated Directional

Solidification Furnace, three lead tin telluride

(PbSnTe) crystals were grown while Columbia

orbited in three different attitudes, to determine

how these orientations affect crystal growth. This

knowledge is expected to help researchers

develop processes, and semiconductor materials

that perform better and cost less to produce.

The Isothermal Dendritic Growth Experiment

(IDGE) on USMP-3 achieved its mission

objectives. After collecting data to answer some

of the questions opened by the USMP-2 results,

research has shown that the small variations in

dendritic growth rates (how fast the tree-like solid

pattern in a molten metal forms) measured in

microgravity on the Space Shuttle are not due to

variations in the microgravity environment on
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

61

orbit. The investigators are currently completing

measurements on the three-dimensional shape

of these dendritic tips, which will further

advance the empirical basis from which more

accurate solidification models are being

developed and tested. This is an early step in

what will ultimately be solidification models that

could be used to make less expensive and more

reliable cast or welded metal and alloy products.

The IDGE team also participated in an important

technology demonstration by commanding a

microgravity space instrument from a remote

site located at the Rensselaer Polytechnic

Institute. This first-ever remote commanding to

the Shuttle from a U.S. university campus

foreshadows operations aboard the International

Space Station.

Investigators for the Critical Fluid Light

Scattering Experiment were successful in

observing, with unprecedented clarity, xenon’s

critical point behavior-the precise temperature

and pressure at which it exists as both a gas and

a liquid. The transparent xenon sample

displayed the unusual critical point condition,

with maximum light scattering followed by a

sudden increase in cloudiness. This effect was

much more distinctive than observed during the

USMP-2 mission and happened at a lower

temperature than expected. Knowledge gained

from this experiment will prove valuable for

applications from liquid crystals to

superconductors.

This mission was the first flight of a Glovebox

facility in the Middeck section of the Shuttle.

Three combustion science investigations were

conducted by the crew. The Forced Flow

Flamespreading Test burned 16 paper samples,

both flat and cylindrical. Video of the cylindrical

samples showed significant differences in flame

size, growth rate, and color with variations in air

flow speed and fuel temperature. The

Comparative Soot Diagnostics investigation

completed 25 combustion experiment runs. The

As we move toward the era of the International Space Station,

more experiment monitoring and control is being performed from

NASA centers and university laboratories “remote“ from

Marshall Space Flight Center and Johnson Space Center.

Glovebox Investigation Module hardware.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

62

The Space Shuttle Columbia, carrying the Life and Microgravity

Spacelab, launched from Kennedy Space Center June 20, 1996.

team obtained excellent results, testing the

effectiveness of two different smoke-sensing

techniques, for detecting fires aboard the Shuttle

and the International Space Station. The Radiative

Ignition and Transition to Spread Investigation

team observed new combustion phenomena, such

as tunneling flames which move along a narrow

path instead of fanning out from the burn site.

Also, for the first time, these investigators studied

the effects of sample edges and corners on fire

spreading in microgravity.

Life and Microgravity Spacelab,

June 1996

The Life and Microgravity Spacelab mission

successfully completed a 17 day flight on July 6,

1996. For this mission there was an unprecedented

distribution of teams monitoring their experiments

around the world, with experiment commanding

performed from three sites.

A number of researchers conducted experiments

using the Advanced Gradient Heating Facility

(AGHF) from the European Space Agency. Three

aluminum-indium alloys were directionally

solidified to study the physics of solidification

processes in immiscible alloys called monotectics.

The three samples, which differed only in indium

content, were processed at the same growth rate

to permit a comparison of microstructures, how

the indium was distributed in the aluminum matrix.

Two of these samples were of compositions which

cannot be processed under steady state conditions

on Earth due to gravitationally-driven convective

instabilities and subsequent sedimentation of the

liquid indium.

Another AGHF experiment used commercial Albased samples to obtain insight into the

mechanism of particle redistribution during

solidification. Additional studies were geared

toward enhancement of the fundamental

understanding of the dynamics of insoluble

particles at solid/liquid interfaces. The physics of

the problem is of direct relevance to such areas as

solidification of metal matrix composites,
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

63

management of defects such as inclusions and

porosity in metal castings, development of high

temperature superconductor crystals with

superior current carrying capacity, and the

solidification of monotectics.

A series of experiments was performed in the

Advanced Protein Crystallization Facility. The

experiments were generally successful in terms of

yielding crystals. Those crystals which showed

particular promise, based on early microscopic

examination, were ferritin, satellite tobacco

mosaic virus, satellite panicum mosaic virus,

Iysozyme, and canavalin.

Several experiments were conducted using the

Bubble, Drop and Particle Unit (BDPU) from the

European Space Agency. In one experiment, the

transition to periodic and chaotic convection was

detected. The results of this experiment will

trigger ground based research on the nonlinear

dynamics of convecto-diffusive systems. In

another experiment, thermocapillary flows in two

and three layer systems were observed for five

temperature gradients. The results of this

experiment will improve our understanding of

heat and mass transfer in other fluid physics

research.

An additional experiment studied the interaction

between pre-formed gas bubbles inside a solid

and a moving solid/liquid interface, obtained by

heating an initially solid sample. Early results

concerning the release of bubbles from the

melting front indicate that once a hole has been

made and the gas inside the bubble contacts the

liquid then the liquid enters the cavity (by wetting

the solid walls) and pushes out the gas inside the

bubble.

The scientific results of one set of BDPU

experiments provide us with new insights into

bubble dynamics and into evaporation. This will

lead to a better understanding and modeling of

steam generation and boiling. Initial findings of

another experiment showed that, under

Magnification of a sample of an aluminum-indium alloy. When

the sample is melted then controllably solidifies in the AGHF; the

indium forms in cylindrical fibers within a solid aluminum matrix.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

64

Schematic diagram of Space Shuttle Orbiter docked to Mir.

microgravity conditions, boiling heat transfer is

still as efficient as under normal Earth gravity. In

contrast to the existing theory the findings show

that the influence of Earth gravity is less than

predicted. The heat transfer in a microgravity

environment is still as efficient, sometimes even

more efficient than, at normal gravity.

Real-time Orbital Acceleration Research

Experiment data were used by the science teams

to monitor the microgravity environment during

their experiment operations. The effects of

mission activities, such as venting of unneeded

water and Orbiter orientation changes, were

presented to help the science teams understand

the environment in which their experiments

operated. The Microgravity Measurement

Assembly (MMA) used this mission to verify a

new system, augmented by a newly developed

accelerometer for measuring the quasi-steady

range. MMA provided real-time quasi-steady and

g-jitter data to the science teams during the

mission.

Shuttle/Mir Science Program,

March 1995 to May 1998

Although competition in the space program has

existed between the United States and Russia for

some time, there has also been a rich history of

cooperation that has grown into the highly

successful joint science program that it is today.

One part of that program is geared towards

microgravity research.

Many of the investigations from that program are

configured to run in a Glovebox facility that has

been installed in the Priroda research module of

the Mir Space Station. The Microgravity Isolation

Mount (MIM) is also located in Priroda. The MIM

was developed by the Canadian Space Agency to

isolate experiments attached to it from ongoing gjitter. The MIM is also able to induce defined

vibrations so that the effects of specific

disturbances on experiments can be studied.

Additional experiments are being performed in

individual experiment facilities that have been

placed in the Priroda and other Mir modules.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

65

Various protein crystal growth experiments use

the Gaseous Nitrogen Dewar (GN2 Dewar).

Samples are placed in the GN2 Dewar and it is

charged with liquid nitrogen, freezing them. The

system is designed so that the life of the nitrogen

charge lasts long enough to get the payload

launched and into orbit. As the system absorbs

heat, the nitrogen boils away and the chamber

approaches ambient temperature. As the samples

thaw, crystals start growing in the Dewar. The

crystals are allowed to form throughout the long

duration mission and are returned to Earth for

analysis. Initial investigations using the Dewar

served as a proof of concept for the experiment

facility. Successive experiment runs using

different samples will continue to improve our

knowledge of protein crystal structures.

The Diffusion-Controled Crystallization Apparatus

for Microgravity experiment is designed primarily

for the growth of protein crystals in a

microgravity environment. It uses the liquid/liquid

and dialysis methods in which a precipitant

solution diffuses into a bulk solution. In the

experiment, a small protein sample is covered by

a semipermeable membrane that allows the

precipitant solution to pass into the protein

solution to initiate the crystallization process.

Diffusion starts on Earth as soon as the chambers

are filled. However, the rate is so slow that no

appreciable change occurs before the samples

reach orbit one or two days later. Such an

apparatus is ideally suited for the long duration

Mir missions.

The Cartilage in Space—Biotechnology System

experiment began with cell cultures being

transported to Mir by the Shuttle in September

1996 on mission STS-79. The investigation is a

test bed for the growth, maintenance, and study

of long-term on-orbit cell growth in microgravity.

The experiment investigates cell attachment

patterns and interactions among cell cultures as

well as cellular growth and the cellular role in

forming functional tissue.

Protein and virus crystals grown in the GN2 Dewar on Mir.

Thaumatin Alpha Amylase

Creatine Kinase STMV

Ribonuclease Rhombohedral

Canavalin

Myoglobin Hemoglobin
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

66

The Biotechnology System-Cartilage in Space Experiment in

orbit. Top: Astronauts Carl Walz (left) and Jay Apt prepare the

experiment for transfer frorn the middeck of the Space Shuttle

Atlantis to the Priroda module of Mir Bottom: Walz and Apt test

the bioreactor media for pH, carbon dioxide, and oxygen levels.

The Candle Flames in Microgravity investigation

conducted 79 candle tests in the Glovebox in July

1996. The experiments explored whether wick

flames (candles) can be sustained in a purely

diffusive environment or in the presence of a very

slow, sub-buoyant convective flow. An associated

goal was to determine the effect of wick size and

candle size on burning rate, flame shape and

color, and to study interactions between two

closely spaced diffusion flames. Preliminary data

indicate long-term survivability with evidence of

spontaneous and prolonged flame oscillations

near extinction (when the candle goes out).

The Forced Flow Flame Spreading Tests ran in the

Glovebox in early August 1996. The investigations

studied flames spreading over solid fuels in lowspeed air flows in microgravity. The effects of

varying fuel thickness and flow velocity of flames

spreading in a miniature low-speed wind tunnel

were observed. The data are currently being

analyzed and compared to theoretical predictions

of flame spreading. The numerical model

predicted that the flame would spread at a steady

rate and would not experience changes in speed,

shape, size, or temperature.

The Interface Configuration Experiment Glovebox

investigation studied how a liquid with a free

surface in contact with a container behaves in

microgravity. This provides a basis for predicting

the locations and configurations of fluids with the

use of mathematical models. The data are

currently being analyzed.

The Technological Evaluation of the MIM (TEM)

was a technology demonstration to determine the

capabilities of the MIM. Through observations of

liquid surface oscillations, TEM evaluated the

ability of the MIM to impart controlled motions.

The data are still being analyzed. A follow-on

technology demonstration (TEM-2) was

transferred to Mir in September 1996.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

67

The Binary Colloidal Alloy Test Glovebox

investigation was also launched to Mir on STS-79

in September 1996. The objective is to conduct

fundamental studies of the formation of gels and

crystals from binary colloid mixtures.

The Angular Liquid Bridge and Opposed Flow

Flame Spread Glovebox investigations were

carried to Mir by the Shuttle on mission STS-81

in early 1997. The former is an extension of

previous fluid physics investigations conducted

on the Shuttle and Mir and studies the behavior

and shape of liquid bridges, liquid that spans the

distance between two solid surfaces. The

objective of the latter is to extend the

understanding of the mechanisms by which

flames spread, or fail to spread, over solid fuel

surfaces in the presence of an opposing oxidizer

flow.

A Space Acceleration Measurement System

(SAMS) unit was launched to Mir on a Progress

rocket in August 1994. Starting in October 1994,

the SAMS was used to measure and characterize

the microgravity environment of various Mir

modules in support of microgravity experiments.

Between October 1994 and September 1996,

SAMS collected about sixty gigabytes of

acceleration data. The data have been used to

identify common vibration sources, as has been

done with the Shuttles. This information has

helped experimenters plan the timing and location

of their experiments. The Passive Accelerometer

System is a simple tool that is being used to

estimate the quasi-steady microgravity

environment of Mir during the increment between

STS-79 and STS-81. The motion of a steel ball in

a water-filled glass tube is tracked and the

distance travelled over time is used to estimate

accelerations caused by atmospheric drag and the

location of the tube with respect to Mir’s center of

gravity.

Vibration Frequencies Commonly Seen in

Mir Accelerometer Data

Freq. (Hz) Disturbance Source

 0.6 Kristall structural mode

 1.0 Kristall structural mode

 1.1 structural mode

 1.2 structural mode

 1.3 Kristall structural mode

 1.9 Kristall structural mode

 2.75 structural mode

 3.75 structural mode

15 air quality system

 24.1 humidifier/dehumidifier

30 air quality system harmonic

41 fan

 43.5 fan

45 air quality system harmonic

90 air quality system harmonic

 166.6 gyrodyne (system used to

maintain Mir orientation)
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

68

This illustration depicts the International Space Station in its

completed and fully operational state with elements from the

United States, Europe, Canada, Japan, and Russia.

Future

Directions

Microgravity science has come a long way since

the early days of space flight when researchers

realized that they might be able to take advantage

of the reduced gravity environment of orbiting

spacecraft to study different phenomena. Shuttle

and Mir based experiments that study

biotechnology, combustion science, fluid physics,

fundamental physics, and materials science have

opened the doors to a better understanding of

many of the basic scientific principles that drive

much of what we do on Earth and in space.

To reach the next level of understanding about

phenomena in a microgravity environment, we

need to perform experiments for longer periods

of time, to be able to conduct a series of

experiments as is done on Earth, and to have

improved environmental conditions. The

International Space Station is being developed as

a microgravity research platform. Considerable

attention has been given to the design of the

station and experiment facility components so

that experiments can be performed under highquality microgravity conditions. The International

Space Station will provide researchers with

continuous, controlled microgravity conditions for

up to thirty days at a time. (The time in between

these thirty day increments is used for vibrationintensive activities such as Shuttle dockings,

station reconfiguration, and upkeep.) This is

almost twice as long as the microgravity periods

available on the Space Shuttle and there will be a

better environment than that provided by Mir. This

increase in experiment time and improvement in

conditions will be conducive to improved

understanding of microgravity phenomena.

Continued microgravity research on the Shuttles,

Mir, and on the International Space Station will

lead to, among other things, the design of
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

69

improved drugs, fire protection and detection

systems, spacecraft systems, high-precision

clocks, and semiconductor materials. In addition,

this research will allow us to create outposts on

the Moon where we can build habitats and

research facilities. The end result of research in

microgravity and on the Moon will be the

increased knowledge base necessary for our trips

to and exploration of Mars.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

71

Glossary

Acceleration–The rate at which an object’s

velocity changes with time.

Altitude–Height above Earth’s mean sea level.

Apparent Weight–The net sum of all forces acting

on a body is its apparent weight.

Biotechnology–Any technique that involves the

research, manipulation, and manufacturing of

biological molecules, tissues, and living

organisms to improve or obtain products, or

perform specific functions.

Buoyancy–Driven Convection Convection created

by the difference in density between two or more

fluids in a gravitational field.

Capillarity–The attraction a liquid has for itself

versus the attraction it has for a solid surface,

such as the liquid’s container.

Combustion Science–The study of the process of

burning.

Concave–Curved inward like the inner surface of

a sphere.

Convection–Energy and/or mass transfer in a

fluid by means of bulk motion of the fluid .

Convex–Curved like the outer surface of a sphere.

Critical Point–The temperature at which the

differences between liquids and gases disappear.

Above that temperature, the liquid smoothly

transforms to the gaseous state; boiling

disappears.

Dendrites–Branching structures that develop as a

molten metal solidifies under certain conditions.

Density–The mass of a body divided by its

volume (average density).

Differentiation–The process by which cells and/

or tissues undergo a progressive specialization of

form or function.

Diffusion–lntermixing of atoms and/or molecules

in solids, liquids, and gases due to a difference in

composition.

Dopant–An impurity intentionally added to a pure

semiconductor to alter its electronic or optical

properties.

Drop Facility–Research facility that creates a

microgravity environment by permitting

experiments to freefall through an enclosed

vertical tube.

Fluid–Anything that flows (liquid or gas).

Fluid Physics–The study of the properties and

motions of liquids, gases, and fluid-like solids.

Force–An action exerted upon a body in order to

change its state, either of rest, or of uniform

motion in a straight line.

Freefall–Falling in a gravitational field where the

acceleration is the same as that due to gravity

alone.

Fundamental Physics–The study of several

physics subfields, including studies where

interaction forces are weak, where extremely

uniform samples are required, where objects

must be freely suspended and their acceleration

must be minimized, and where mechanical

disturbances that are unavoidably present in

Earth-bound laboratories must be eliminated.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

72

G–Universal Gravitational Constant (6.67x10-11 N

m2/kg2)

g–The acceleration Earth’s gravitational field

exerts on objects at Earth’s surface

(approximately 9.8 meters per second squared).

g-jitter–The vibrations experienced by

microgravity experiments (for example on

parabolic aircraft and the Space Shuttle) that

cause effects similar to those that would be

caused by a time-varying gravitational field.

Gradient–The variation of a quantity such as

temperature with respect to a given parameter,

typically distance, °C/cm.

Gravitation–The attraction of objects due to their

masses.

Homogeneous–Uniform in structure and/or

composition.

Immiscible–The situation where two or more

liquids do not mix chemically.

Inertia–A property of matter that causes it to

resist changes in velocity.

Joule Heating–Heating a material by flowing an

electric current through it.

Law of Universal Gravitation–A law stating that

every mass in the universe attracts every other

mass with a force proportional to the product of

their masses and inversely proportional to the

square of the distances between their centers.

Materials Science–The study of developing

quantitative and predictive relationships between

the processing, structure, and properties of

materials.

Microgravity (μg)–An environment in which the

apparent weight of a system is small compared to

its actual weight (due to gravity).

Morphology–The form and structure of an object.

Nucleus–A source upon which something, such

as a crystal, grows or develops.

Quasi-steady Acceleration–Accelerations in

spacecraft related to the position in the

spacecraft, aerodynamic drag, and vehicle

rotation.

Regolith–A layer of powder-like dust and loose

rock that rests on bedrock. In the case of the

moon, fragmentation of surface rocks by

meteorite bombardment created much of the

regolith material.

Rheology–The scientific study of the deformation

and flow of matter.

Satellite–A natural or man-made object that

orbits a celestial body.

Semiconductor–A substance, such as germanium

and silicon, that is a poor electrical conductor at

room temperature but is improved by minute

additions of certain substances (dopants) or by

the application of heat, light, or voltage; a material

with a forbidden energy gap less than 3 eV.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

73

Skylab–NASA’s first orbital laboratory that was

operated in 1973 and 1974.

Spacelab–A scientific laboratory developed by

the European Space Agency that is carried into

Earth orbit in the Space Shuttle’s payload bay.

Speed–The magnitude of velocity.

Surfactant–A substance added to a liquid to

change its surface tension.

Velocity–The rate at which the position of an

object changes with time; it is a vector quantity.

Weight–The weight of an object is the

gravitational force exerted on it by Earth.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

75

Activities

Activity Matrix..................................................................................................................................76

Microgravity In The Classroom........................................................................................................79

Accelerometers ................................................................................................................................88

Around The World ...........................................................................................................................95

Inertial Balance ..............................................................................................................................101

Gravity-Driven Fluid Flow...............................................................................................................109

SurfaceTension-Driven Flows ........................................................................................................114

Temperature Effects on Surface Tension........................................................................................119

Candle Flames ...............................................................................................................................124

Candle Flames in Microgravity .......................................................................................................129

Crystallization Model .....................................................................................................................135

Crystal Growth and Buoyancy-Driven Convection Currents ...........................................................141

Rapid Crystallization ......................................................................................................................148

Microscopic Observation of Crystal Growth ..................................................................................152

Zeolite Grystal Growth ...................................................................................................................159
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

76

Activity Matrix

Standards and Skills

Science as Inquiry Physical Science

-position & motion of objects - properties of objects and materials

Unifying Concepts & Processes

Change, Constancy, & Measurement

- evidence, models, & explanation

Science & Technology - abilities of technologic design - understanding about science & technology

Science in Personal & Social Perspectives

Science & Technology in Local Challenges

Science Standards

Microgravity In The Classroom

Accelerometers

Around The World

Inertial Balance

Gravity-Driven Fluid Flow

Surface Tension-Driven Flows

Temp. Effects on Surface........

Candle Flames

Candle Flames in Microgravity

Crystallization Model

Crystal Growth and Buoy.....

Rapid Crystallization

Microscopic Observation of....

Zeolite Crystal Growth

Observing Communicating

Measuring Collecting Data

Inferring

Predicting

Making Models

Making Graphs Hypothesizing Interpreting Data

Controlling Variables

Defining Operationally

Investigating

Science Process Skills

Microgravity In The Classroom

Accelerometers

Around The World

Inertial Balance

Gravity-Driven Fluid Flow

Surface Tension-Driven Flows

Temp. Effects on Surface........

Candle Flames

Candle Flames in Microgravity

Crystallization Model

Crystal Growth and Buoy.....

Rapid Crystallization

Microscopic Observation of....

Zeolite Crystal Growth
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

77

Problem Solving Communication

Reasoning Connections

Number & Number Relationships

Computation & Estimation

Patterns & Functions

Statistics Probability Geometry

Mathematics Standards

Microgravity In The Classroom

Accelerometers

Around The World

Inertial Balance

Gravity-Driven Fluid Flow

Surface Tension-Driven Flows

Temp. Effects on Surface........

Candle Flames

Candle Flames in Microgravity

Crystallization Model

Crystal Growth and Buoy.....

Rapid Crystallization

Microscopic Observation of....

Zeolite Crystal Growth
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

79

Objective:

• To demonstrate how microgravity is

created by freefall.

Science Standards:

Science as Inquiry

Physical Science

- position and motion of objects

Change, Constancy, & Measurement

- evidence, models, & exploration

Science Process Skills:

Observing

Communicating

Making Models

Defining Operationally

Investigating

Predicting

Mathematics Standards:

Computation & Estimation

Measurement

Activity Management:

This activity consists of three demonstrations that

create microgravity conditions by freefall. Although

the first demonstration is best done by the teacher,

the other demonstrations can be done as activities by

students working in groups of three or four.

Each demonstration requires a clear space where

drop tests can be conducted. Two of the

demonstrations require water and you should have a

mop, sponges, or paper towels available to clean up

any mistakes.

Begin with the Falling Weight apparatus teacher

demonstration. Before dropping the device, conduct a

discussion with the students to consider possible

outcomes. Ask students to predict what they think

will happen when the device is dropped. Students will

focus on the proximity of the balloon and the needle.

Screws

Screws

Various objects demonstrate microgravity as they are

dropped.

Falling weight apparatus

(see special instructions)

Plastic cup

Small cookie sheet or

plastic cutting board

Empty soft drink can

Nail or some other punch

Catch basin - plastic dish

pan, bucket, large waste

barrel

Mop, paper towels, or

sponges for cleanup

Will the balloon break when the device is

dropped? If the balloon does break, will

it break immediately or when the device

hits the floor? Try to get students with

different predictions to debate each

other. After the debate, drop the device.

Microgravity In The Classroom

MATERIALS AND TOOLS
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

80

Be sure to hold the wooden frame by the middle

of the top cross piece. Hold it out at arm’s length

in case the weight and needle bounce your way.

Discuss the demonstration to make sure the

students understand why the balloon popped

when it did. Before trying any of the other

demonstrations, student groups should read the

student reader entitled Microgravity.

The second and third demonstrations can also be

done by the teacher or by small groups of

students. One student drops or tosses the test

item and the other students observe what

happens. Students should take turns observing.

Assessment:

Have students write a paragraph or two that

define microgravity and explain how freefall

creates it.

Extensions:

1. Videotape the demonstrations and play back

the tape a frame at a time. Since each second

of videotape consists of 30 frames, the tape

can be used as a simple timing device. Count

each frame as onethirtieth of a second.

2. Replace the rubber bands in the falling weight

apparatus with heavy string and drop the

apparatus again to see whether the balloon

will break. Compare the results of the two

drops.

3. Conduct a microgravity science field trip to an

amusement park that has roller coasters and

other rides that involve quick drops. Get

permission for the students to carry accelerometers on the rides to study the gravity

environments they experience. On a typical

rollercoaster ride, passengers experience

normal g (gravity), microgravity, high g, and

negative g.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

81

Gravity is an attractive force that all objects have

for one another. It doesn’t matter whether the

object is a planet, a cannonball, a feather, or a

person. Each exerts a gravitational force on all

other objects around it.

The amount of force between two objects

depends upon how much mass each contains and

the distance between their centers of mass. For

example, an apple hanging from a tree branch will

have less gravitational force acting on it than

when it has fallen to the ground. The reason for

this is because the center of mass of an apple,

when it is hanging from a tree branch, is farther

from the center of mass of Earth than when Iying

on the ground.

Student Reader - 1

Microgravity

Although gravity is a force that is always with us,

its effects can be greatly reduced by the simple

act of falling. NASA calls the condition produced

by falling microgravity.

You can get an idea of how microgravity is

created by looking at the diagram below. Imagine

riding in an elevator to the top floor of a very tall

building. At the top, the cables supporting the car

break, causing the car and you to fall to the

ground. (In this example, we discount the effects

of air friction on the falling car.) Since you and the

elevator car are falling together, you feel like you

are floating inside the car. In other words, you

and the elevator car are accelerating downward at

the same rate due to gravity alone. If a scale were

present, your weight would not register because

the scale would be falling too.

The ride is lots of fun until you

get to the bottom.

NASA uses several different

strategies for conducting

microgravity research. Each

strategy serves a different

purpose and produces a

microgravity environment with

different qualities. One of the

simplest strategies is the use of

drop towers. A drop tower is like

a high-tech elevator shaft. A small

experiment package is suspended

from a latch at the top. The

package contains the experiment,

television or movie cameras, and

a radio or wire to transmit data

during the test. For some drop

towers, when the test is ready, air

from the shaft is pumped out so

Normal

weight

Heavier

than normal

Lighter

than normal

No apparent

weight

The person in the stationary elevator car experiences normal weight. In

the car immediately to the right, weight increases slightly in the next car

because of the downward acceleration. No weight is measured in the

last car on the right because of freefall.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

82

the package will fall more smoothly. The cameras,

recording equipment, and data transmitter are

turned on as a short countdown commences.

When T minus zero is reached, the package is

dropped.

NASA has several drop tower facilities including

the 145 meter drop tower at the NASA Lewis

Research Center in Cleveland, Ohio. The shaft is

6.1 meters in diameter and packages fall 132

meters down to a catch basin near the shaft’s

bottom. For 5.2 seconds, the experiment

experiences a microgravity environment that is

about equal to one one-hundred-thousandth

(lx10-5) of the force of gravity experienced when

the package is at rest.

If a longer period of microgravity is needed, NASA

uses a specially equipped jet airplane for the job.

Most of the plane’s seats have been removed and

the wall, floor, and ceiling are covered with thick

padding similar to tumbling mats.

One of the advantages of using an airplane to do

microgravity research is that experimenters can

ride along with their experiments. A typical flight

lasts 2 to 3 hours and carries experiments and

crew members to a beginning altitude about 7

kilometers above sea level. The plane climbs

rapidly at a 45-degree angle (pull up) and follows

a path called a parabola. At about 10 kilometers

high, the plane starts descending at a 45-degree

angle back down to 7 kilometers where it levels

out (pull out). During the pull up and pull out

segments, crew and experiments experience a

force of between 2 g and 2.5 g. The microgravity

experienced on the flight ranges between one

one-hundredth and one one-thousandth of a g.

On a typical flight, 40 parabolic trajectories are

flown. The gut-wrenching sensations produced

on the flight have earned the plane the nickname

of “Vomit Comet.”

Student Reader - 2

For the first few seconds of the pull up, the

experiments and experimenters onboard the airplane

feel a gravity force of about two times normal. During

the upper portion of the parabola, microgravity is

produced that ranges from one onehundredth to one

one-thousandth of a g. During the pull out, the gravity

force again reaches about two times normal.

A parabola is the mathematical shape you get if you

slice a cone in the way shown in the picture.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

83

Small rockets provide a third technology for

creating microgravity. A sounding rocket follows a

parabolic path that reaches an altitude hundreds

of kilometers above Earth before falling back. The

experiments onboard experience several minutes

of freefall. The microgravity environment

produced is about equal to that produced onboard

falling packages in drop towers.

Although airplanes, drop facilities, and small

rockets can be used to establish a microgravity

environment, all of these laboratories share a

common problem. After a few seconds or

minutes of low-g, Earth gets in the way and the

freefall stops. When longer term experiments

(days, weeks, months, and years) are needed, it is

necessary to travel into space and orbit Earth. We

will learn more about this later.

Student Reader -3

Typical design of a sounding rocket used for

microgravity research.

Launch

High-g acceleration

Payload separation

Microgravity

Parabolic Trajectory

Deceleration

Recovery

Telemetry

Microgravity begins when the rocket arrives above

Earth’s atmosphere and the payload section is

released. Microgravity ends when the payload falls

back into the atmosphere and begins feeling

atmospheric drag.

In a few years, it will be possible to conduct

sensitive microgravity experiments, lasting

many months, on the International Space

Station.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

84

Falling Weight

Apparatus

Construction:

1. Assemble the rectangular supporting frame as

shown in the diagram. Be sure to drill pilot

holes for the screws and glue the frame

pieces before screwing them together. Brace

the front and back of each corner with small

triangles of plywood. Glue and nail them in

place.

2. Drill a 1/2 inch-diameter hole through the

center of the top of the frame. Be sure the

hole is free of splinters.

3. Twist the two screw eyes into the underside of

the top of the frame as shown in the diagram.

(Before doing so, check to see that the metal

gap at the eye is wide enough to slip a rubber

band over it. If not, use pliers to spread the

gap slightly.)

4. Join three rubber bands together and then

loop one end through the metal loop of the

fishing sinker.

5. Follow the same procedure with the other

three rubber bands. The fishing weight should

hang downward like a swing, near the bottom

of the frame as shown in the illustration. If the

weight hangs near the top, the rubber bands

are too strong. Replace them with thinner

rubber bands. If the weight touches the

bottom, remove some of the rubber bands.

6. Attach the needle to the weight, with the point

upward. There are several ways of doing this

depending upon the design of the weight. If

the weight has a loop for attaching it to

fishing line, hold the needle next to the loop

with tape or low-temperature hot glue.

Another way of attaching the needle is to drill

a small hole on top of the weight to hold the

needle.

Screws

Screws

MATERIALS AND TOOLS

MATERIALS NEEDED:

2 pieces of wood 16x2x1 in.

2 pieces of wood 10x2x1 in.

4 wood screws (#8 or #10 by 2 in.)

8 corner brace triangles from 1/4 in.

plywood

Glue

2 screw eyes

4-6 rubber bands

1 6-oz fishing sinker or several

lighter sinkers taped together

Long sewing needle

Small round balloons (4 in.)

String

Drill, 1/2 in. bit, and bit for piloting

holes for wood screws

Screwdriver

Pillow or chair cushion

(Optional - Make a second frame with

string supporting the sinker.)
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

85

Explanation:

When stationary, the lead fishing weight stretches

the rubber bands so the weight hangs near the

bottom of the frame. When the frame is dropped,

the whole apparatus goes into freefall. The

microgravity produced by the fall removes the

force the fishing weight is exerting on the rubber

bands. Since the stretched rubber bands have no

force to counteract their tension, they pull the

weight—with the needle—up toward the balloon,

causing it to pop. (In fact, the sinker’s

acceleration toward the balloon will initially be

zero due to the energy released as the rubber

bands relax to their normal, unstretched length.)

If a second frame, with string instead of rubber

bands supporting the weight, is used for

comparison, the needle will not puncture the

balloon as the device falls because the strings will

not rebound like the rubber bands did.

In tests of this device using a television camera

and videotape machine as a timer (see

extensions), the balloon was found to pop in

about 4 frames which is equal to fourthirtieths of

a second or 0.13 seconds. Using the formula for a

falling body (see below), it was determined that

the frame dropped only about 8 centimeters

before the balloon popped. This was the same as

the distance between the balloon and the needle

before the drop.

d = 1

 2

d = 1

 2

d is the distance of the fall in meters

a is the acceleration of gravity in meters per

second squared

t is the time in seconds

Use:

Inflate the balloon and tie off the nozzle with a

short length of string. Thread the string through

the hole and pull the balloon nozzle through. Pull

the string snugly and tape it to the top of the

frame.

Demonstration:

1. Place a pillow or cushion on the floor. Hold

the frame above the pillow or cushion at

shoulder level.

2. Ask the students to predict what will happen

when the entire frame is dropped.

3. Drop the entire unit onto the cushion. The

balloon will pop almost immediately after

release.

at 2

x 9.8 m/s2x( 0.13s)2=0 08m
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

86

Procedure:

1. Place the catch basin in the center of an open

 area in the classroom.

2. Fill the cup with water.

3. Place the cookie sheet over the opening of the

cup. Press the cup tight to the sheet while

inverting the sheet and cup.

4. Hold the cookie sheet and cup high above the

catch basin. You may wish to stand on a sturdy

tahle or climb on a stepladder to raise the cup

higher.

5. While holding the cookie sheet level, slowly

slide the cup off the edge of the cookie sheet

and observe what happens.

6. Refill the cup with water and invert it on the

cookie sheet.

7. Quickly pull the cookie sheet straight out from

under the cup and observe the fall of the cup

and water.

8. (Optional) Videotape the cup drop and play

back the tape frame-to-frame to observe what

happens to the water.

Explanation:

Air pressure and surface tension keep the water

from seeping around the cup’s edges while it is

inverted on the cookie sheet. If the cup were

slowly pushed over the edge of the sheet, the

water would pour out. However, when the sheet is

quickly pulled out from under the filled cup, the

cup and water both fall at the same time. Since

they are both accelerated downward by gravity an

equal amount, the cup and water fall together. The

water remains in the cup but the lower surface of

the water bulges. Surface tension tends to draw

liquids into spherical shapes. When liquids are at

rest, gravity overcomes surface tension, causing

drops to spread out. In freefall, gravity’s effects

are greatly reduced and surface tension begins to

draw the water in the cup into a sphere.

Falling Water

MATERIALS AND TOOLS

Plastic drinking cup

Cookie sheet (with at least one edge

without a rim)

Catch basin (large pail, waste basket)

Water

Chair or stepladder (optional)

Towels

Television camera, videotape

recorder, and monitor (optional)
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

87

Procedure:

1. Punch a small hole with a nail near the bottom

of an empty soft drink can.

2. Close the hole with your thumb and fill the can

with water.

3. While holding the can over a catch basin,

remove your thumb to show that the water falls

out of the can.

4. Close the hole again and stand back about 2

meters from the basin. Toss the can through the

air to the basin, being careful not to rotate the

can in flight.

5. Observe the can as it falls through the air.

6. (Optional) Videotape the can toss and play back

the toss frame-to-frame to observe the hole of

the can.

Explanation:

When the can is stationary, water easily

pours out of the small hole and falls to the

catch basin. However, when the can is tossed,

gravity’s effects on the can and its contents are

greatly reduced. The water remains in the can

through the entire fall including the upward

portion. This is the same effect that occurs on

aircraft flying in parabolic arcs.

Can Throw

MATERIALS AND TOOLS

Empty aluminum soft drink can

Sharp nail

Catch basin

Water

Towels

Television camera, videotape

recorder, and monitor (optional)
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

88

Objective:

• To measure the acceleration

environments created by different

motions.

Science Standards:

Physical Science

- position and motion of objects

Unifying Concepts and Processes

Change, Constancy, & Measurement

Science and Technology

- abilities of technological design

Science Process Skills:

Communicating

Measuring

Collecting Data

Mathematics Standards:

Communication

Number & Number Relationships

Measurement Computation &

Estimation

Activity Management:

 This activity provides students with the

plans for making a one-axis

accelerometer that can be used to

measure acceleration in different

environments ranging from +3 g to -3 g.

The device consists of a triangular shaped

poster board box they construct with a

lead fishing sinker suspended in its

middle with a single strand of a rubber

band. Before using the device, students

must calibrate it for the range of

accelerations it can measure.

The pattern for making the accelerometer

box is included in this guide. It must be

doubled in size. It is recommended that

Accelerometers

-3

-2

-1

 0

 1

 2

 3

Students construct a device that can measure

acceleration environments from +3 to -3 9.

MATERIALS AND TOOLS

Lightweight poster board

(any color)

3 “drilled egg” lead fishing

sinkers, 1 ounce size

Masking tape

Rubber band, #19 size

4 small paper clips

Scissors

Straightedge

Ballpoint pen

Pattern

Hot glue (low temperature)

several patterns be available for the students to

share. To save on materials, students can work in

teams to make a single accelerometer. Old file

folders can be substituted for the poster board.

The student reader can be used at any time during

the activity.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

89

The instructions call for three egg (shaped)

sinkers. Actually, only one is needed for the

accelerometer. The other two are used for

caiibrating the accelerometer and can be shared

between teams.

When the boxes are being assembled, the three

sides are brought together to form a prism shape

and held securely with masking tape. The ends

should not be folded down yet. A rubber band is

cut and one end is inserted into a hole punched

into one of the box ends. Tie the rubber band to a

small paper clip. This will prevent the end of the

rubber band from sliding through the hole. The

other end of the rubber band is slipped through

the sinker first and then tied off at the other end

of the box with another paper clip. As each rubber

band end is tied, the box ends are closed and held

with more tape. The two flaps on each end

overlap the prism part of the box on the outside.

It is likely that the rubber band will need some

adjustment so it is at the right tension. This can

be easily done by rolling one paper clip over so

the rubber band winds up on it. When the rubber

band is lightly stretched, tape the clip down.

After gluing the sinker in place on the rubber

band, the accelerometer must be calibrated. The

position of the sinker when the box is standing on

one end indicates the acceleration of 1 gravity (1

g). By making a paper clip hook, a second sinker

is hung from the first and the new position of the

first sinker indicates an acceleration of 2g9. A

third sinker indicates 3 g. Inverting the box and

repeating the procedure yields positions for

negative 1, 2, and 3 g. Be sure the students

understand that a negative g acceleration is an

acceleration in a direction opposite gravity’s pull.

Finally, the half way position of the sinker when

the box is laid on its side is 0 g.

Students are then challenged to use their

accelerometers to measure various accelerations.

They will discover that tossing the device or

letting it fall will cause the sinker to move, but it

will be difficult to read the scale. It is easier to

read if the students jump with the meter. In this

case, they must keep the meter in front of their

faces through the entire jump. Better still would

be to take the accelerometer on a fast elevator, on

a trampoline, or a roller coaster at an amusement

park.

Assessment:

Test each accelerometer to see that it is

constructed and calibrated properly. Collect and

review the student sheets.

Extensions:

1. Take the accelerometer to an amusement park

and measure the accelerations

Magnetic Accelerometer

Three ring magnets with like poles facing each other.

you experience riding a roller coaster and other

fast rides.

2. Construct a magnetic accelerometer.

3. Design and construct an accelerometer for

measuring very slight accelerations such as

those that might be encountered on the Space

Shuttle.

2

1

0

1

2

Magnetic Pole Arrangement

2

1

0

1

2

N

S

S

N

N

S
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

90

Accelerometer Box Pattern

5 cm 5 cm 5 cm 5 cm

27 cm

2 cm

19 cm

5 cm

4 cm

Enlarge 2X

Hole for rubber

band

Hole for rubber

band

4 cm
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

91

Acceleration is the rate at which an object’s velocity is changing. The change can be in how

fast the object is moving, a direction change, or both. If you are driving an automobile and

press down on the gas pedal (called the accelerator), your velocity changes. Let’s say you

go from 0 kilometers to 50 kilometers per hour in 10 seconds. Your acceleration is said to

be 5 kilometers per hour per second. In other words, each second you are going 5

kilometers per hour faster than the second before. In 10 seconds, you reach 50 kilometers

per hour.

You feel this acceleration by being pressed into the back of your car seat. Actually, it is the

car seat pressing against you. Because of the property of inertia, your body resists

acceleration. You also experience acceleration when there is a change in direction. Let’s say

you are driving again but this time at a constant speed in a straight line. Then, the road

curves sharply to the right. Without changing speed, you make the turn and feel your body

pushed into the left wall of the car. Again, it is actually the car pushing on you. This time,

your acceleration was a change in direction. Can you think of situations in which

acceleration is both a change in speed and direction?

The reason for this discussion on acceleration is that it is important to understand that the

force of gravity produces an acceleration on objects. Imagine you are standing at the edge

of a cliff and you drop a baseball over the edge. Gravity accelerates the ball as it falls. The

acceleration is 9.8 meters per second per second. After 5 seconds, the ball is traveling at a

rate of nearly 50 meters per second. To create a microgravity environment where the

effects of gravity on an experiment are reduced to zero, NASA would have to accelerate

that experiment (make it fall) at exactly the same rate gravity does. In practice, this is hard

to do. When you jump into the air, the microgravity environment you experience is about

1/100th the acceleration of Earth’s gravity. The best microgravity environment that NASA’s

parabolic aircraft can create is about 1/1000th g. On the Space Shuttle in Earth orbit,

microgravity is about one-millionth g. In practical terms, if you dropped a ball there, the

ball would take about 17 minutes just to fall 5 meters!

Acceleration

G

r

a

v

i

t

y

Student Reader - 1
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

92

The instructions below are for making a measuring device called an accelerometer. Accelerometers are

used to measure how fast an object changes its speed in one or more directions. This accelerometer

uses a lead weight suspended by a rubber band to sense changes in an object’s motion.

Student Worksheet - 1

Accelerometer Construction

and Calibration

Building the Accelerometer:

1. Trace the pattern for the accelerometer on a

piece of poster board. Cut out the pattern.

2. Use a ruler and a ballpoint pen to draw the fold

lines on the poster board in the same place

they are shown on the pattern. As you draw the

lines, apply pressure to the poster board. This

will make the poster board easier to fold.

3. Fold the two long sides up as shown in the first

illustration. The left side with the tabs is folded

over first. The right side is folded second. This

makes a long triangle shape. Use tape to hold

the sides together.

4. Punch a small hole in one of the end triangles.

Cut the rubber band to make one long elastic

band. Tie one end of the band to a small paper

clip. Thread the other end through the hole.

5. Slip the lead weight on the band. Punch a hole

in the other end triangle. While stretching the

band, slip the free end through the second hole

and tie it to a second paper clip.

6. Set the triangular box on its side so the window

is up. Slide the weight so it is in the middle of

the elastic band. Put a dab of hot glue on each

end of the weight where the elastic band enters

the holes.

7. If the elastic band sags inside the box, roll the

elastic around one of the paper clips until it is

snug. Then tape the paper clip in place. Tape

the other triangular end in place.

Fold this side first.

The two flaps are on

the inside. Fold this side

second and tape

to hold.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

93

Calibrating the Accelerometer:

1. Stand the accelerometer on one end. Using a

pencil, mark one side of the accelerometer next

to the middle of the weight. Identify this mark

as 1 g.

2. Using a small paper clip as a hook, hang a

second weight on the first. Again, mark the

middle of the first weight on the accelerometer.

Identify this mark as 2 g. Repeat this step with

a third weight and identify the mark as 3 g.

3. Remove the two extra weights and stand the

accelerometer on its other end. Repeat the

marking procedure and identify the marks as -

1 g, -2 g, and -3 g.

4. The final step is to mark the midway position

between 1 and -1 g. Identify this place as 0 g.

The accelerometer is completed.

Student Worksheet - 2

Fold ends after rubber band and

weight are attached. The two flaps

on each end are folded to the outside.

Tape

Tape

-3

-2

-1

 0

 1

 2

 3

Finished Accelerometer
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

94

Instrument Construction Team:

Student Worksheet - 3

Accelerometer Tests

Test your accelerometer by jumping in the air

with it a few times. What happens to the position

of the sinker?

What g forces did you encounter in your jumps?

Where else might you encounter g forces like

these?

Explain how your accelerometer measures

different accelerations.

Design Activity:

How can this accelerometer be redesigned so it is more sensitive to slight accelerations?

Make a sketch of your idea below and write out a short explanation.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

95

Objective:

• To create a model of how satellites orbit

Earth.

Science Standards:

Science as Inquiry

Physical Science

- position and motion of object

Change, Constancy, & Measurement

- evidence, models, & exploration

Science Process Skills:

Observing

Communicating

Making Models

Defining Operationally Investigating

Mathematics Standards:

Communication

Geometry

Activity Management:

This activity can be conducted as a

demonstration or a small group activity at a

learning station where student groups take

turns.

Pick a small ball to which it is easy to

attach a string. A small slit can be cut into

a tennis ball or racquetball with a sharp

knife. Then, a knotted string can be shoved

through the slit. The slit will close around

the string. A screw eye can be screwed into

a solid rubber or wood ball and a string

attached to it.

If using this as an activity, have students

work in groups of two. The large ball and

flowerpot should be placed on the floor

inan open area. Tell students to imagine the

Around The World

A ball on a string circles a ball to simulate

the orbits of satellites around Earth.

MATERIALS AND TOOLS

Large ball*

Small ball

2 meters of string

Flower pot*

* A world globe can substitute

for the large ball and flower pot

ball is Earth with its north pole straight up. One

student will stand near the ball and pot and hold

the end of the string the small ball is attached to.

This student’s hand should be held directly over

the large ball’s north pole, and enough string

should be played out so that the small
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

96

ball comes to rest where the large ball’s equator

should be. While the first student holds the string

steadily the second student starts the small ball

moving. The objective is to move the small ball in

a direction and at a speed that will permit it to

orbit the big ball.

Save the student reader for use after students

have tried the activity.

Additional Information:

This model of a satellite orbiting around Earth is

effective for teaching some fundamentals of

orbital dynamics. Students will discover that the

way to orbit the small ball is to pull it outward a

short distance from the large ball and then start it

moving parallel to the large ball’s surface. The

speed they move it will determine where the ball

ends up. If the small ball moves too slowly, it will

arc “down” to Earth’s surface. NASA launches

orbital spacecraft in the same way. They are

carried above most of Earth’s atmosphere and

aimed parallel to Earth’s surface at a particular

speed. The speed is determined by the desired

altitude for the satellite. Satellites in low orbits

must travel faster than satellites in higher orbits.

In the model, the small ball and string become a

pendulum. If suspended properly, the at-rest

position for the pendulum is at the center of the

large ball. When the small ball is pulled out and

released, it swings back to the large ball.

Although the real direction of gravity’s pull is

down, the ball seems to move only in a horizontal

direction. Actually, it is moving downward as well.

A close examination of the pendulum reveals that

as it is being pulled outward, the small ball is also

being raised higher off the floor.

The validity of the model breaks down when

students try orbiting at different distances from

the large ball without adjusting the length of the

string. To make the small ball orbit at a higher

altitude without lengthening the string, the ball

has to orbit faster than a ball in a lower orbit. This

is the opposite of what happens with real

satellites.

Assessment:

Use the student pages for assessment.

Extensions:

1. Investigate the mathematical equations that

govern satellite orbits such as the relationship

between orbital velocity and orbital radius.

2. Learn about different kinds of satellite orbits

(e.g., polar, geostationary, geosynchronous)

and what they are used for.

3. Look up the gravitational pull for different

planets. Would there be any differences in

orbits for a planet with a much greater

gravitational pull than Earth’s? Less than

Earth’s?

4. Use the following equation to determine the

velocity a satellite must travel to remain in

orbit at a particular altitude:

v = velocity of the satellite in meters

GM = gravitational constant times Earth’s mass

(3.99x1014 meters 3

/sec2 )

r = Earth’s radius (6.37x106 meters) plus the

altitude of the satellite

GM

r

V =
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

97

A microgravity environment is created by letting

things fall freely. NASA uses airplanes, drop

towers, and small rockets to create a microgravity

environment lasting a few seconds to several

minutes. Eventually, freefall has to come to an

end because Earth gets in the way. When

scientists want to conduct experiments lasting

days, weeks, months, or even years, it is

necessary to travel into space and orbit Earth.

Having more time available for experiments

means that slower processes and more subtle

effects can be investigated.

To see how it is possible to establish microgravity

conditions for long periods of time, it is first

necessary to understand what keeps a spacecraft

in orbit. Ask just about anybody what keeps

satellites and Space Shuttles in orbit and you will

probably hear, “There is no gravity in space.” This

is simply not true. Gravity is what keeps a satellite

or Space Shuttle from drifting into space. It does

this by bending an orbiting object’s path into a

circular shape. To explain how this works, we can

use an example presented by English scientist Sir

Isaac Newton. In a book he wrote in 1673,

Philosophiae Naturalis Principia Mathematica

(Mathematical Principles of Natural Philosophy),

Newton explained how a satellite could orbit

Earth.

Newton’s cannon fires the first cannonball. The combination

of the cannonball’s initial velocity and the pull of Earth’s

gravity causes the cannonball to arc to the ground near the

mountain.

Student Reader - 1

Around The World

Resulting

Path

Gravity

Initial Direction

A second cannonball is fired using a larger charge of black

powder. The force exerted on the cannonball causes it to

travel faster than the first cannonball. Gravity bends its path

into an arc but because of the greater speed, the cannonball

travels farther before it lands on Earth.

Newton envisioned a very tall mountain on Earth

whose peak extended above Earth’s atmosphere.

This was to eliminate friction with Earth’s

atmosphere. Newton then imagined a cannon at

the top of that mountain firing cannonballs

parallel to the ground. As each cannonball was

Greater

Force

Gravity
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

98

Gravity

Greater

Force

Gravity

Greater

Force

Student Reader - 2

fired, it was acted upon by two forces. One force,

due to the explosion of the black powder,

propelled the cannonball straight outward. If no

other force were to act on the cannonball, the

shot would travel in a straight line and at a

constant velocity. But Newton knew that a second

force would also act on the cannonball: Earth’s

gravity would cause the path of the cannonball to

bend into an arc ending at Earth’s surface.

Newton demonstrated how additional cannonballs

would travel farther from the mountain if the

cannon were loaded with more black powder each

time it was fired. With each shot, the path would

lengthen and soon the cannonballs would

disappear over the horizon. Eventually, if a

cannonball were fired with enough energy it

would fall entirely around Earth and come back to

its starting point. This would be one compiete

orbit of Earth. Provided no force other than

gravity interfered with the cannonball’s motion, it

would continue circling Earth in that orbit.

In essence, this is how the Space Shuttle stays in

orbit. The Shuttle is launched on a path that arcs

above Earth so that the Orbiter is traveling parallel

to the ground at the right speed. For example, if

the Shuttle climbs to a 1 60-kilometer-high orbit,

it must travel at a speed of about 28,300

kilometers per hour to achieve an orbit. At that

speed and altitude, the Shuttle’s falling path will

be parallel to the curvature of Earth. Because the

Space Shuttle is freefalling around Earth, a

microgravity environment is created that will last

as long as the Shuttle remains in orbit.

This cannonball travels halfway around Earth because

of the greater charge of black powder used. The

cannonball’s falling path nearly matches the shape of

Earth.

The black powder charge in this final cannon shot

propels the ball at exactly the right speed to cause it

to fall entirely around Earth. If the cannon is moved

out of the way, the cannonball will continue orbiting

Earth.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

99

2.

1.

Procedure:

1. Set up your equipment as shown in the picture.

One team member stands above the large ball

and holds the end of the string. The second

team member’s job is to move the small ball in

different ways to answer the following

questions. Write down your answers where

indicated and draw pictures to show what

happened. Draw the pictures looking straight

down on the two balls.

Orbital Deployment Around The Team Members:

World

North

Pole

Equator

1. What path does the satellite (small ball) follow

when it is launched straight out from Earth?

EARTH

Show what happened.

Student Worksheet - 1
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

100

2. What path does the satellite follow when it is

launched at different angles from Earth’s

surface?

5. Using the results of your investigation and the

information contained in the student reader,

write a paragraph that explains how satellites

remain in arbit.

Student Worksheet - 2

EARTH

Show what happened.

3. What effect is there from launching

the satellite at different speeds?

4. What must you do to launch the satellite so it

completely orbits Earth?

6. Why will the International Space Station be an

excellent place to conduct microgravity

research?
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

101

Objective:

• To demonstrate how mass can be

measured in microgravity.

Science Standards:

Science as Inquiry

Physical Science

- position and motion of objects

Unifying Concepts and Processes

Change, Constancy, & Measurement

Science Process Skills:

Observing

Communicating

Measuring

Collecting Data

Making Graphs

Interpreting Data

Controlling Variables

Mathematics Standards:

Communication

Number & Number Relationships

Computation & Estimation

Measurement

Activity Management:

 Before doing this activity, you will need to

construct enough inertial balances for the

entire class. Plan on having one balance

for every three or four students. Except

for the empty film canisters, which are

free from photo processors, materials and

tools for making all the balances can be

obtained at a hardware store where

lumber is also sold. To reduce your cost,

buy hacksaw blades in multipacks. The

dimensions for the wood blocks are not

critical and you may be able to find a

piece of scrap lumber to meet your needs.

The only tools needed to construct the

balances are a crosscut or backsaw to cut

Inertial Balance

Objects of unknown mass are measured with a balance that

works in microgravity.

the wood into blocks and a coping saw to cut the

notch for insertion of the blade. If you have access

to power tools, use a table scroll saw to cut the

notches. The notches should be just wide enough

for the hacksaw blade to be slid in. If the notches

are too wide, select a thinner blade for the coping

or scroll saw.

MATERIALS AND TOOLS

Hacksaw blade (12 inch)

Coping saw (optional)

1 C-clamp (optional)

Plastic 35mm film canister

Tissue paper

Masking tape

Wood block (1x2.5x4 inch)

Wood saws

Glue

Objects to be measured

Graph paper, ruler, and pencil

Pennies and nickels

Stopwatch
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

102

Cut the blocks, one for each balance, about 10

centimeters long. Cut a 2 centimeter deep notch

in one end of each block. Slip one end of the

hacksaw blade into the notch to check the fit. It

should be snug. Remove the blade and apply a

small amount of glue to both sides of the end and

slip the blade back in place. Make sure the blade

is slightly above and parallel to the bottom flat

side of the block. Set the balance aside to dry.

Use tape to attach a film canister to the opposite

end of each balance. Squirt hot glue into the

bottom of the canister and drop in a large metal

washer. Repeat two more times. The reason for

doing this is to provide extra mass to the canister

end of the inertial balance. Students will be

counting how long it takes the device to oscillate

from side to side 25 times. A very light canister

will swing faster than the students can count.

Extra mass will slow the device so that counting

is possible.

To use the inertial balance, students will place the

wood block on the edge of a table

Side View

Insert blade with glue.

Use tape to cover saw teeth.

Tape 35mm film canister

to end of blade.

Cut small notch in

wood. Insert and

glue end of blade.

12 inch hacksaw blade

6.5 X 2.5X 10 cm

wood block

6.5 X 2.5 X 10 cm
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

103

so the hacksaw and canister stick over the edge.

The balance can be anchored with a clamp or just

pressed to the tabletop by one student in the

team. An object of unknown mass is placed in the

canister and the students determine its mass by

deflecting the blade so it swings from side to

side. Unknown masses can be such things as

nuts and bolts, washers, and pebbles. The tissue

paper called for in the instructions anchors the

unknown object in the canister so it will not slosh

around and throw off the accuracy.

The first step for students is to calibrate the

balance. This is done with a standard mass such

as a penny. The length of time the balance takes

to oscillate 25 times is measured for zero through

10 pennies. The results are plotted on a graph

When an unknown mass is placed in the canister,

its time will be measured. By referring to the

graph, students will be able to determine the

unknown object’s mass by seeing where it falls on

the graph. The mass will be given in units of

pennies. If desired, the balance can be calibrated

in grams by measuring the pennies on a metric

beam balance.

Save the student reader for use after the activity.

Assessment:

Collect calibration graphs and data sheets.

Extensions:

1. Construct and demonstrate inertia rods. The

instructions follow. The materials list is found

on the next page.

A. Using a saw, cut the PVC tube in half. Smooth

out the ends, and check to see that the caps fit

the ends.

B. Squeeze a generous amount of silicone rubber

sealant into the end of one of the tubes. Slide

the pipe into the tube. Using the dowel rod,

push the pipe to the middle of the tube. Add

sealant to the other end of the tube and insert

0 1 2 3 4 5 6 7 8 9 10

2 0

1 9

1 8

1 7

1 6

1 5

1 4

1 3

1 2

1 1

1 0

Seconds per 25 Cycles

Number of Pennies

Penny

Nickel

Sample Graph

the second pipe. Position both pipes so they

are touching each other and straddling the

center of the tube.

Set the tube

aside to dry.

C. Squeeze sealant

into the ends of

the second tube.

Push the remaining

pipes into the ends

 of the tubes until

the ends of the

pipes are flush with the tube ends. Be sure

there is enough compound to cement the pipes

in place. Set the tube aside to dry.

D. When the sealant of both tubes is dry, check to

see that the pipes are firmly cemented in place.

If not, add additional sealant to complete the

cementing. Weigh both rods. If one rod is

lighter than the other, add small amounts of

sealant to both ends of the lighter rod. Reweigh. Add more sealant if necessary.

E. Spread some sealant on the inside of the PVC

caps. Slide them onto the ends of the tubes to

cement them in place.

F. Use fine sandpaper to clean the rods.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

104

Demonstrate the rods by having a student pick up

both of the rods from their upper ends and tell the

class whether the rods feel the same. Then, the

student grasps each rod by its middle, extends

arms, and twists the rods side to side as rapidly

as possible. One rod will be easy to twist and the

other difficult. The effect is caused by the

distribution of the mass in each rod. Because the

ends of the rods move more rapidly than the

middle during twisting, the student feels more

inertia in the rods with the masses at the ends

than the rod with the masses in the middle. Relate

this experience to the way the inertial balances

operate.

2. Ask students to design an inertial balance that

automatically counts oscillations.

3. Have students enter their calibration data into a

graphing calculator and use the calculator to

determine unknown masses when new

measurement results are entered.

Weight

Weight

Weight

PVC 3/4 in. water tube

(about 1.5 to 2 m long)

4 iron pipe nipples (4-6 in. Iong

sized to fit inside PVC pipe)

4 PVC caps to fit water pipe

Silicone rubber sealant

Scale or beam balance

Saw

Very fine sandpaper

1/2 in. dowel rod MATERIALS AND TOOLS
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

105

The microgravity environment of an orbiting

Space Shuttle or space station presents many

research problems for scientists. One of these

problems is measurement of mass. On Earth,

mass measurement is simple. Samples, such as a

crystal, or subjects, such as a laboratory animal,

are measured on a scale or beam balance. In a

scale, springs are compressed by the object being

measured. The amount of compression tells what

the object’s weight is. (On Earth, weight is related

to mass. Heavier objects have greater mass.)

Beam balances, like a seesaw, measure an

unknown mass by comparison to known masses.

With both these devices, the force produced by

Earth’s gravitational attraction enables them to

function.

In microgravity, scales and beam balances don’t

work. Setting a sample on the pan of a scale will

not cause the scal.e springs to compress. Placing

a subject on one side of a beam balance will not

affect the other side. This causes problems

for researchers. For example, a

life science study on the nutrition

of astronauts in orbit may

require daily monitoring of an

astronaut’s mass. In materials

science research, it may be

necessary to determine how the

mass of a growing crystal

changes daily. How can mass be

measured without gravity’s

effects?

Mass can be measured in

microgravity by employing

inertia. Inertia is the property

of matter that causes it to resist

acceleration. If you have ever

Student Reader - 1

Inertia and Microgravity

tried to push anything that is heavy, you know

about inertia. Imagine trying to push a truck. You

will quickly realize that the amount of inertia or

resistance to acceleration an object has is directly

proportional to the object’s mass. The more

mass, the more inertia. By directly measuring an

object’s inertia in microgravity, you are indirectly

measuring its mass.

The device employed to measure inertia and,

thereby, mass is the inertial balance. It is a spring

device that vibrates the subject or sample being

measured. The object to be measured is placed in

the sample tray or seat and anchored. The

frequency of the vibration will vary with the mass

of the object and the stiffness of the spring (in

this activity, the hacksaw blade). An object with

greater mass will vibrate more slowly than an

object with less mass. The time needed to

complete a given number of cycles is measured,

and the mass of the object is calculated.

Payload Commander Dr. Rhea Seddon is shown using the Body Mass

Measurement Device during the Spacelab Life Sciences 2 mission. The device

uses the property of inertia to determine mass.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

106

Measuring Mass

With Inertia

Calibrating the Inertial Balance:

1. Clamp the inertial balance to the table so the

spring (saw blade) and sample bucket extends

over the edge of the table.

2. Pick one member of your team to be the

timekeeper, another to record data, and

another to count cycles. Refer to the box to the

right for details on how to perform each task.

3. Begin calibration by inserting a wad of tissue

paper in the bucket and deflecting the spring.

Release the bucket and start counting cycles.

When the time for 25 cycles is completed,

enter the number in the data chart and plot the

point on the graph for zero pennies. To

improve accuracy, repeat the measurements

several times and average the results.

4. Insert 1 penny into the bucket next to the tissue

paper wad and measure the time it takes for 25

cycles. Record the data as 1 penny.

5. Repeat the procedure for 2 through 10 pennies

and record the data.

Student Work Sheet - 1

Counter: Pull the sample bucket a few

centimeters to one side and release it. At the

moment of release, say “Now” and begin

counting cycles. A cycle is completed when the

sample bucket starts on one side, swings across

to the other and then returns to its starting point.

When 25 cycles are complete, say “Stop.”

Timer: Time the number of cycles being counted

to the nearest tenth of a second. Start timing

when the counter says “Now” and stop when the

counter says “Stop.”

Recorder: Record the time for 25 cycles as

provided to you by the timer. There will be 11

measurements. Plot the measurements on the

graph and draw a line connecting the points.

6. Draw a line that goes through or close to all

points on the graph. Your inertial balance is

calibrated.

Using the Inertial Balance:

1. Place an unknown object in the inertial balance

bucket. Remember to use the same tissue

paper for stuffing. Measure the time for 25

cycles. And record your answer.

2. Starting on the left side of the graph, find the

number of seconds you measured in step 1.

Slide straight over to the right until you reach

the graph line you drew in the previous activity.

From this intersection point, go straight down

to the penny line. This will tell you the mass of

the unknown object in penny weights.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

107

Measuring Mass

With Inertia

Student Work Sheet - 2

Measurement Team:

0 1 2 3 4 5 6 7 8 9 10

2 0

1 9

1 8

1 7

1 6

1 5

1 4

1 3

1 2

1 1

1 0

Seconds per 25 Cycles

Number of Pennies

Calibration Graph

Unknown Object 1

Mass: __________________ pw

Unknown Object 2

Mass: __________________ pw

Unknown Object 3

Mass: __________________ pw

Unknown Object 4

Mass: __________________ pw
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

108

Questions:

1. Will this technique for measuring mass work in microgravity? Yes______ No______

Explain your answer:

2. Why was it necessary to use tissue paper for stuffing?

3. How could you convert the penny weight measurements into grams?

4. Would the length of the hacksaw blade make a difference in the results?

5. What are some of the possible sources of error in measuring the cycles?

6. What does a straight line in the calibration graph imply?

Student Work Sheet - 3
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

109

Objective:

• To study gravity-driven fluid flow that

is caused by differences in solution

density.

Science Standards:

Science as Inquiry

Physical Science

- position and motion of objects

- properties of Objects and Materials

Unifying Concepts and Processes

Change, Constancy, & Measurement

Science and Technology

- abilities of technological design

Science Process Skills:

Observing

Communicating

Collecting Data

Inferring

Hypothesizing

Interpreting Data

Controlling Variabies

I nvestigating

Activity Management:

In this activity, students combine liquids

of different densities to observe the fluid

flow caused by gravity-driven buoyancy

and settling. The activity is best done in

student groups of two or three. It can

also be done as a demonstration for the

entire class. In this case, obtain an

overhead projector and place beakers on

the lighted stage. The light from below

will illuminate the contents of the jars to

make them easily visible from across the

room. To reduce distraction, cover the

projector lens to prevent blurry images

from falling on the wall or screen behind.

Caution: Be careful not to spill liquid on

the projector.

Gravity-Driven Fluid Flow

Water of different densities is mixed to produce

gravity-driven fluid flow.

If using this as an activity, provide each student

group with a set of materials. Salt canisters, food

coloring dispensers, and measuring cups can be

shared among groups. The materials list calls for

glass beakers or tall drinking glasses. Other

containers can be substituted such as mason jars

or plastic jars like those in which peanut butter is

sold.

MATERIALS AND TOOLS

2 large (500 ml) glass beakers

or tall drinking glasses

2 small (5 to 10 ml) glass vials

Thread

Food coloring

Salt

Spoon or stirring rod

Measuring cup (1/4 cup)

Water

Paper towels
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

110

The vials are available from school science supply

catalogs for a few dollars per dozen. Choose glass

vials with screw tops and a capacity of 3 to 4 ml.

Small cologne sample bottles can be substituted

for the vials. It is important that the vials or

bottles are not too large because the process of

lowering large containers into the beakers can stir

up the water too much. It is recommended you tie

the string around the neck of the vial yourself to

make sure there is no slippage.

The student instructions ask the students to

conduct three different experiments. In the first,

the effects of saltwater and freshwater are

investigated. In the second, the effects of warm

and cold water are investigated. The third

experiment is an opportunity for students to

select their own materials. They might try mixing

oil and vinegar, sugar and saltwater, or oil and

water. It may be necessary for the third

experiment to be conducted on another day while

the new materials are collected.

Give each student group at least one set of

instructions and two data sheets. Save the

student reader for use after the experiment.

Assessment:

Discuss the experiment results to determine

whether the students understand the concepts of

buoyancy and sedimentation. Collect the student

pages for assessment of the activity.

Extensions:

1. How could this experiment be conducted if it

were not possible to use food coloring for a

marker? (In experiments where the density of

the two fluids is very close, the addition of

food coloring to one fluid could alter the

results.)

2. Design an apparatus that can be used to

combine different fluids for experiments on the

future International Space Station.

3. Design an experiment apparatus that would

permit the user to control the buoyancy and

sedimentation rates in the beakers.

4. Design an experiment to measure the gravitydriven effects on different fluids in which the

fluids are actually gases.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

111

Gravity is an important force at work in the

movement of fluids. Fluids can be liquids or

gases. The important thing about fluids is they

can flow from place to place

and can take the shape of the

container they are in.

When you pour a liquid from

one container into another,

gravity is the driving force that

accomplishes the transfer.

Gravity also affects fluids “at

rest” in a container. Add a

small amount of heat to the

bottom of the container and

the fluid at the bottom begins

to rise. The heated fluid

expands slightly and becomes

less dense. In other words, the

fluid becomes buoyant. Cooler

fluid near the top of the container is more dense

and falls or sinks to the bottom.

Many crystals grow in solutions of different

compounds. For example, crystals of salt grow in

concentrated solutions of salt dissolved in water.

In the crystal growth process, the ions that make

up the salt come out of solution and are deposited

on the crystal to make it larger. When this

happens, the solution that held the molecule

becomes a little less salty than it was a moment

Student Reader - 1

Gravity-Driven Fluid Flow

ago. Consequently, the density of the solution is a

little bit less than it was. This, in turn, causes a

fluid flow in the solution. The slightly less salty

solution is buoyant and rises

to the top of the container

while saltier, or more dense,

solution moves in to take its

place.

Scientists are interested in

gravity-driven fluid flows

because they have learned

that these flows, when

occurring during the growth

of crystals, can create subtle

changes in the finished

crystals. Flaws, called defects,

are produced that can alter the

way those crystals perform in

various applications. Crystals

are used in many electronic applications, such as

in computers and lasers.

To learn how to grow improved crystals on Earth,

scientists have been growing crystals in the

microgravity environment of Earth orbit.

Microgravity virtually eliminates gravity-driven

fluid flows and often produces crystals of

superior quality to those grown on Earth. One of

the major areas of materials science research on

the International Space Station will involve crystal

growth.

Dyed freshwater in saltwater beaker
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

112

Procedure

1. Fill the first beaker with freshwater and set it on

the lab surface. Also fill the second beaker with

freshwater. Into the second beaker add

approximately 50 to 100 grams of salt. Stir the

water until the salt is dissolved.

2. Dip the first small glass vial into the beaker

with freshwater. Fill it nearly to the top. Add a

couple of drops of food coloring to the water in

the vial. Close the top of the vial with your

thumb and shake the water until the food

coloring is mixed throughout. Place this vial

next to the saltwater beaker.

3. Partially fill a second vial with salty water and

food coloring. After mixing, place it in front of

the beaker filled with freshwater.

4. Wait a few minutes until the water in the two

beakers is still. Gently lift one of the vials by

the string and slowly lower it into the beaker

next to it. Let the vial rest on its side on the

bottom of the beaker and drape the string over

the side as shown in the pictures. Answer the

questions on the data sheets and sketch what

you observed in the diagrams.

5. Place the second vial in the other beaker as

before. Make your observations, sketch what

you observed, and answer the questions about

the data.

Student Work Sheet - 1

Gravity-Driven Fluid Flow

Second Experiment Procedure:

1. Empty the two beakers and rinse them

thoroughly.

2. Fill one beaker with cold water and the other

with warm water.

3. Repeat steps 2 through 5 in the previous

experiments.

Original Experiment:

1. On a blank sheet of paper, write a proposal for

an experiment of your own design that uses

different materials in the beakers. Include in

your proposal an experiment hypothesis, a

materials list, and the steps you will follow to

conduct your experiment and collect data.

Submit your experiment to your teacher for

review.

2. If your experiment is accepted for testing,

• gather your materials

• conduct the experiment

• submit a report summarizing your

 observations and conclusions
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

113

Research Team Members:

Gravity-Driven Fluid Flow

Data Sheet

Student Work Sheet - 2

Beaker and Vial:

1. Water in beaker (check one)

Fresh _____

Salty _____

2. Water in vial (check one)

Fresh _____

Salty _____

3. Describe and explain what happened

Sketch what happened.

Sketch what happened.

Beaker and Vial:

1. Water in beaker (check one)

Fresh _____

Salty _____

2. Water in vial (check one)

Fresh _____

Salty _____

3. Describe and explain what happened
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

114

Objective:

• To study surface tension and the fluid

flows caused by differences in

surface tension.

Science Standards:

Science as Inquiry

Physical Science

- position and motion of objects

- properties of objects and materials

Unifying concepts and processes

Change, Constancy, &

Measurement

- evidence, models, & exploration

Science Process Skills:

Observing

Communicating

Measuring

Collecting Data

Inferring

Predicting

Interpreting Data

Investigating

Activity Management:

The purpose of this activity is to

demonstrate how surface tension

changes can cause fluids to flow. It

requires shallow trays with raised edges

such as cafeteria trays. Large Styrofoam

food trays from a supermarket can also

be used, but they should be the kind

with a smooth surface and not a waffle

texture. Light-colored trays make a

better background for seeing the

surface tension effects. Encourage

students to try different mazes and

investigate the effects of wide versus

narrow mazes.

Surface Tension-Driven Flow

A clay maze is constructed on a cafeteria tray. Water

is added. A drop of liquid soap disrupts the surface

tension of the water and creates currents that are

made visible with food coloring.

Cafeteria tray (with raised edge)

Plasticine modeling clay

Water

Liquid soap

Food coloring

Toothpick

Paper towels

Bucket or basin for waste water MATERIALS AND TOOLS

Water handling will be a bit of a problem. After a

drop of liquid soap is applied to the water, the

water must be discarded and replaced before

trying the activity again. Carrying shallow waterfilled trays to a sink could be messy. Instead, it is

recommended that a bucket or large waste basket

be brought to the trays so the trays can be

emptied right at the workstation.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

115

When soap is applied to the water, food coloring

at the water’s surface will be driven along the

maze by the disruption of the water’s surface

tension. Make sure students observe what

happens to the water at the bottom of the tray as

well. A reverse current flows along the bottom to

fill in for the water that was driven along the

surface.

Save the student reader for use after the activity.

Assessment:

Conduct a class discussion to ensure the students

understand that variations in surface tension in a

fluid cause fluid flow. Collect the student pages.

Extensions:

1. Demonstrate additional surface tension effects

by shaking black pepper into a

glass of water. Because of surface

tension, the pepper will float. When a drop of

soap is added to the water, the pepper will

sink. This same effect can be seen in a broader

view by placing water into a petri dish and

adding pepper ancl then soap. The pepper will

be driven to the sides of the dish where

particles will start sinking. The petri dish

experiment can be done as a demonstration

with an overhead projector.

2. Make a surface tension-propelled paper boat by

cutting a small piece of paper in the shape

shown to the right and floating it on clean

water. Touch a small amount of detergent to

the water in the hole at the back of the boat.

3. Design an experiment to test whether the

temperature of a liquid has any effect on

surface tension.

4. Try floating needles on water and observe what

happens when detergent is added. To float the

needle, gently lower it to the water’s surface

with a pair of tweezers.

Surface Tension Paper Boat

(actual size)
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

116

If you have ever looked closely at drops of water,

you will know that drops try to form spherical

shapes. Because of gravity’s attraction, drops that

cling to an eye dropper, for example, are

stretched out. However, when the drops fall they

become spherical.

Student Reader - 1

Surface Tension

The shape of a water drop is a result of surface

tension. Water is composed of molecules

consisting of two hydrogen atoms and one atom

of oxygen. These molecules attract each other. In

the middle of a drop of water, molecules attract

each other in all directions so no direction is

preferred. On the surface, however, molecules are

attracted across the surface and inward. This

causes the water to try to pull itself into a shape

that has the least surface area possible-the

sphere. Because of gravity, drops resting on a

surface, like water drops on a well-waxed car,

flatten out somewhat like the figure above.

The molecules on the surface of a liquid behave

like an elastic membrane.You can easily see the

elastic membrane effect by floating a needle on

the surface of a glass of water. Gently lower the

needle to the water surface with a pair of

tweezers. Examine the water near the needle and

you will observe that it is depressed slightly as

though it were a thin sheet of rubber.

The addition of a surfactant, such as liquid soap,

to water reduces its surface tension. Water

molecules do not bond as strongly with soap

molecules as they do with themselves. Therefore,

the bonding force that enables the molecules to

behave like an elastic membrane is weaker. If you

put a drop of liquid soap in the glass with the

needle, the surface tension is greatly reduced and

the needle quickly sinks. When you added liquid

soap to the water in the experiment, the surface

tension was weakened in one place. The water on

the surface immediately began spreading away

from the site of the soap. The clay walls

channeled the flow in one direction. To make up

for the water moving away from the site where

the soap was added, a second water current

formed in the opposite direction along the bottom

of the tray.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

117

Because a microgravity environment greatly

reduces buoyancy-driven fluid flows and

sedimentation, surface tension flows become

very important. Microgravity actually makes it

easier to study surface tension-driven flows. On

Earth, studying surface tension in the midst of

gravity-driven flows is like trying to listen to a

whisper during a rock concert. The importance

of surface tension research in microgravity is

that surface tension-driven flows can interfere

with experiments involving fluids. For example,

crystals growing on the International Space

Student Reader - 2

Car Surface

Air

Molecules inside a water drop are attracted in all directions. Drops on the surface

are attracted to the sides and inward.

Station could be affected by surface tensiondriven flows, leading to defects in the crystal

structure produced. Understanding surface

tension better could lead to new materials

processing techniques that either reduce surface

tension’s influence or take advantage of it. One

example of a positive application of surface

tension is the use of sprayers to paint a surface.

Surface tension causes paint to form very small

droplets that cover a surface uniformly without

forming drips and runs.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

118

Team Members:

Surface Tension-Driven Flows

Student Work Sheet - 1

Setup Instructions:

1. Roll clay into long “worms” 1 to 2 centimeters

in diameter. Lay the worms out on the tray to

produce a narrow valley about 3 to 4

centimeters wide that is closed on one end.

Squeeze the worms so they stick to the tray

and form thin walls.

2. Add water to the tray until it almost reaches the

tops of the maze walls. Let the water settle

before the next step.

3. Add a drop of food coloring to the maze near

its end. Drop the coloring from a height of

about 5 centimeters so that some of the food

coloring spreads out slightly on the surface

while the rest sinks to the bottom.

4. Dip the toothpick in the liquid soap and touch

the end of the toothpick to the water at the end

of the maze beyond the dye. Observe what

happens.

5. Try a different maze to see how far you can get

the dye to travel.

Questions:

1. Why did the surface water move?

2. Did water near the bottom move as well?

If it moved, why ?

Make a sketch of the clay maze you

constructed. Use arrows to show the

direction of surface water movement

after you added the soap. Use dashed

line arrows to indicate the direction of

any subsurface currents.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

119

Objective:

• To investigate the effects of

temperature on the surface tension of

a thin liquid.

Science Standards:

Science as Inquiry

Physical Science

- position and motion of objects

- properties of objects and materials

Unifying Concepts and Processes

Change, Constancy, & Measurement

Science Process Skills:

Observing

Communicating

Measuring

Collecting Data

Inferring

Predicting

Interpreting Data

Controlling Variables

Investigating

Activity Management:

This experiment can be done as a

student activity or a classroom

demonstration for small groups of

students. If done as a demonstration,

it can be set up while students are

conducting the Surface Tension-Driven

Flows activity. Rotate small groups

through the demonstration.

Be sure to use Pyrex® petri dishes for

the demonstration. Also provide eye

protection for yourself and the

students. It is important that teh

heating surface of the hot plate be

Temperature Effects on

Surface Tension

A thin pool of liquid heated from below exhibits polygonal

cell structure due to surface tension-driven flows.

Cooking oil

Powdered cinnamon

Two Pyrex® petri dishes and

covers

Laboratory hot plate

Heat-resistant gloves, hotpad, or

tongs

Ice cubes

M

Eye protection

ATERIALS AND TOOLS

level. Otherwise, it will be necessary to add more

oil to cover the bottom of the petri dish. A thin

layer of oil is essential to the success of the

experiment. Thin layers, on the order of 1 or 2

millimeter, do not exhibit significant convection

currents as do layers that are much thicker. There

simply is not enough room for convection

currents to develop in thin layers. Heat is

conducted through the thin layer to the surface

very quickly. Since the lower and upper parts of
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

120

the liquid are at nearly the same temperature, no

convection currents develop.

The demonstration is conducted with two petri

dishes. Use the lids of both dishes for holding the

oil and spice. To see the surface tension effects,

sprinkle the cinnamon from a height of 20 or 30

centimeters to help it spread out evenly on the

surface of the oil.

Place the first dish on the hot plate and observe

that patterns are produced by the cinnamon.

Before placing the second dish lid on the hot

plate, invert and insert the bottom of the second

dish into the lid. This will effectively place all the

oil in contact with glass so there is not any

exposed oil surface. The reason for the two

different runs of the demonstration is to verify

whether or not buoyancy-driven convection

currents are involved in moving the cinnamon

markers. If these currents are at work, the

cinnamon will spread out and swirl through the

oil. In other words, the second part of the

demonstration is a control for the first part.

Assessment:

Conduct a class discussion on why it is important

for microgravity scientists to understand about

surface tension. Coilect the student pages.

Extensions:

1. Experiment with other fluid and marker

combinations. Several microgravity

experiments in space have used 10 centistoke

silicone oil (dimethylpolysiloxane) with

powdered aluminum as a marker. Both

chemicals are available from chemical supply

catalogs. The demonstration works best if the

aluminum is more flaky than powder.

Aluminum flakes will provide reflective

surfaces that intensify the optical effect. You

can make your own aluminum flakes by

obtaining flat enamel hobby paint and allowing

the aluminum flakes to settle to the bottom of

the bottle. Pour off the fluid and wash the

sediment several times with nail polish

remover and let dry.

2. Videotape the convective flow patterns and piay

them back at different speeds to see more

details on how surface tensiondriven flows

develop.

3. Look for patterns in nature, such as mud

cracks, that are similar to the patterns seen in

this activity. Are nature’s patterns produced in

the same way or by some different

mechanism?
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

121

Around the turn of this century, physicist Henri

Benard discovered that liquid in thin pools heated

from below quickly forms flow patterns

consisting of polygonal cells. He made this

discovery by placing tiny markers in the fluid that

showed how the fluid moved. The cells resembled

those that form due to convection currents when

a pot of soup is heated. The interesting thing

about Benard’s discovery is that buoyancy-driven

convection currents were not responsible for the

flow that was produced.

When a thick pool of liquid is heated from below,

liquid at the bottom expands and becomes less

dense. Because of buoyancy, the less dense liquid

rises to the top of the pool where it spreads out.

Cooler surrounding liquid moves in to take the

place of the warmer fluid that rose to the top. This

liquid heats up, becomes less dense, and also

rises to the top to create a cycle that continues as

long as heat is applied. This cycling is called a

buoyancy-driven convection current.

The problem with studying fluid flows in a heating

pot of soup is that convection currents appear to

be the only force at work. Actually, surface

tension flows are also present but, because they

are of lower intensity, they are masked by the

more violent buoyancy-driven convection

currents. By creating a very thin liquid pool

(about 1 mm or thinner), Bénard was able to

eliminate buoyancy-driven convection. In very

thin liquids there just is not enough vertical

distance for significant buoyancydriven

convection currents to get started. The fluid flow

Benard observed was produced by changes in

surface tension.

In the cooking oil experiment, you observed two

petri dishes with a thin layer of oil and powdered

cinnamon markers. The uncovered dish, when

heated from below, began forming circular cells

that eventually grew into each other to produce

polygonal cells. Heat from hot spots in the hot

plate was quickly conducted to the surface of the

oil. The increase in temperature of the oil reduced

the surface tension in those locations. This

reduction was apparent because the oil flowed

from the center of the hot spots in all directions

to the outside. Compare this action to what

happened when a drop of liquid soap was

touched to the surface of a tray of water in the

previous activity. In the second petri dish, a layer

of glass was placed over the thin oil layer so the

oil did not have an exposed surface. In this

manner, surface tension effects were eliminated.

No fluid flows were observed, meaning that

Student Reader - 1

Temperature

Effects on

Surface

Tension

Polygonal cells produced in a thin pool of liquid heated

from below.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

122

buoyancy-driven convection was not at work. This

demonstration served as a scientific control for

the first experiment.

In fluid physics experiments aboard the Space

Shuttle and the International Space Station,

buoyancy is practically eliminated because of

microgravity. Surface tension, however, becomes

an important force because it is not a gravity

Student Reader - 2

dependent phenomenon. In crystal growing and

other fluid physics experiments, surface

tensiondriven flows can affect the outcome. For

this reason, scientists are trying to understand

the mechanics of surface tension-driven flows in

microgravity.

In these two diagrams, the difference between

buoyancy-driven convection currents (left) and

surface tension-driven convection currents (right) is

shown. Flow in the left diagram is produced by

changes in fluid density brought about by heating the

bottom. Flow in the right diagram is brought about by

reducing surface tension above a heated plate.

Heated Plate

Cooler Surface

Flow

Flow

Warm Fluid

Cool Fluid

Thick Liquid Pool

Heated Plate

Cooler Surface

Cool Warm Cool

Thin Liquid Pool

Magnified view of the polygonal cells that are produced by surface

tensiondriven convection.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

123

Name: _____________________________

1. Sketch the fluid flow patterns that

appeared in the thin pool of cooking oil

when heat was applied to the bottom of

the first petri dish. Indicate with arrows

which direction(s) the fluid flowed.

Student Work Sheet - 1

Temperature Effects on Surface Tension

What effect did an increase in temperature

have on the surface tension of the oil?

Why?

2. Sketch the fluid flow patterns that

appeared when heat was applied to the

bottom of the second petri dish. Indicate

with arrows the direction(s) of any fluid

flows observed.

Explain what you observed.

What effect on surface tension do you

predict lowering the temperature of the oil

would have? How could this be observed?
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

124

Objective:

• To investigate the effect of gravity

on the burning rate of candles.

Science Standards:

Science as Inquiry

Physical Science

- properties of objects & materials

Unifying Concepts & Processes

Change, Constancy, &

Measurement

Science Process Skills:

Observing

Communicating

Measuring

Collecting Data

Inferring

Hypothesizing

Predicting

Investigating

Mathematics Standards:

Measurement

Activity Management:

This activity serves as an introduction

to the candle drop activity that follows.

In both activities, students are

organized into cooperative learning

groups of three. It may be useful to

keep the same groups together for

both activities.

The objective of this activity is to

observe candle flame properties and

prepare students to make

observations of candle flames in

microgravity where observing

conditions are more difficult. Before

Candle Flames

The burning rate and other properties of candle

flames are investigated.

MATERIALS AND TOOLS

Birthday candles (2 per group)

Matches

Balance beam scale (0.1 gm or

greater sensitivity)

Clock with second hand or

stopwatch

Wire cutter/pliers

Wire (florist or craft)

20 cm square of aluminum foil

Eye protection

letting students start the activity, conduct a

discussion on the different observations they can

make. Make a list of terms that can be used to

describe flame shape, size, color, and brightness.

At the end of the experirnent, student groups are

asked to write a hypothesis to explain the

differences observed in the burning of the two

candles. It may be helpful to discuss hypothesis
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

125

writing before they get to that part. The

hypotheses should relate to gravity-induced

effects. In the case of candle 2, the wax of the

candle is above the flame. Convection currents (a

gravity-driven phenomenon) deliver lots of heat to

the candle which causes more rapid melting than

occurs with candle 1. Much of that wax quickly

drips off the candle (gravity pulls the wax off) so

more wick is exposed and the candle burns faster.

The wire used in this activity is a lightweight wire

of the kind used by florists and in craft work. You

can find this wire in craft and hardware stores. Do

not use wire with plastic insulation. The flame of

the candle tipped at an angle of 70 degrees may

reach the wire and begin burning the insulation.

Each group will need two wires about 20

centimeters long. Precut the aluminum foil into

20 centimeter squares. One square is needed for

each group.

Provide each group with one set of student

sheets. Save the student reader for use after the

activity has been completed.

Assessment:

Discuss student observations of the candle

burning and their hypotheses. Collect the student

work sheets for assessment.

Extensions:

1. Burn a horizontally held candle for one minute.

Weigh the candle before lighting it. As it burns,

record the colors, size, and shape of the candle

flame. Weigh the candle again and calculate

how much mass was lost.

2. Repeat the above experiments with the candles

inside a large sealed jar. Let the candles burn

to completion. Record the time it takes each

candle to burn. Determine how and why the

burning rate changed.

3. Burn two candles which are close

together. Record the burning rate and

weigh the candles. Is the burning rate

faster or slower than each candle alone?

Why?

4. Investigate convection currents with a

convection current demonstration apparatus

that is obtained from science supply catalogs,

or construct the apparatus as shown below.

5. Obtain a copy of Michael Faraday’s book, The

Chemical History of a Candle, and do the

experiments described. (See reference list.)

Wooden box with glass

front. Hold glass on

with tape. Open tape

to light candle.

Chimney

made from

glass, food

cans, or pipe.

Light the end of

paper wad and then

blow out. Smoke

will be drawn into

chamber.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

126

Candles are useful for illustrating the complicated

physical and chemical processes that take place

during combustion. The candle flame surface

itself is the place where fuel (wax vapor) and

oxygen mix and burn at high temperatures,

radiating heat and light. Heat from the flame is

conducted down the wick and melts the wax at

the wick base. The liquid wax rises up the wick

because of capillary action. As the liquid wax

nears the flame, the flame’s heat causes it to

vaporize. The vapors are drawn into the flame

where they ignite. The heat produced melts more

wax, and so on.

Student Reader - 1

Candle Flames

Fresh oxygen from the surrounding air is drawn

into the flame primarily because of convection

currents that are created by the released heat. Hot

gases produced during burning are less dense

than the cooler surrounding air. They rise upward

and, in doing so, draw the surrounding air,

containing fresh oxygen, into the flame. Solid

particles of soot, that form in the region between

the wick and flame, are also carried upward by

the convection currents. They ignite and form the

bright yellow tip of the flame. The upward flow of

hot gases causes the flame to stretch out in a

teardrop shape.

Dark Red

Brown

1,000 Co

Light Yellow

1,200 Co

White

1,400 Co

Orange

800 Co

Blue

Luminous

Zone

(Carbon

luminesces

and burns)

Main

Reaction

Zone

Primary

(Initial)

Reaction

Zone

(Carbon particles)

O2

o Dead Space

600 C

H2 2 O, CO

(Unburned

carbon)

2

H O2

CO

OH

C2

O2

Candle Flame Reaction Zones,

Emissions, and Temperature

Convection

Radiation Radiation

Conduction

Candle Flame Energy Flow

Candle flame diagrams adapted from "The Science of Flames" poster,

National Energy Foundation, Salt Lake City, UT.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

127

Candle Flame Research

Team Members:

Student Work Sheet - 1

Candle Flames

Procedure:

1. Make a wire stand for each candle so that it

looks like the picture below.

2. Weigh each candle by standing it on a balance

beam scale and recording its weight in grams

on the chart on the next page.

3. Put on eye protection.

4. Place candle 1 on the aluminum square. Light

the candle and let it burn for 1 minute. While it

is burning, observe what is happening and

write your observations below.

70 o

Candle 2

Candle 1

Draw a life-size picture of the candle flame.

Weigh candle 1 again and record its mass

in the chart.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

128

5. Place candle 2 on the aluminum square. Light

the candle and let it burn for 1 minute. While it

is burning, observe what is happening and

write your observations below.

Student Work Sheet - 2

Draw a life-size picture of the candle flame.

Weigh candle 2 again and record its mass in

the table.

Calculate the difference in mass for each candle

and enter your answers in the table.

Candle Mass Table

Before

burning

mass

After

burning

mass

Difference

 1 2

Summarize your observations below.

Write a hypothesis for how you think a candle will

burn in microgravity.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

129

Objective:

• To observe candle flame properties

in freefall.

Science Standards:

Science as Inquiry

Physical Science

- position and motion of objects

Unifying Concepts & Processes

Change, Constancy, & Measurement

Science &Technology

- abilities of technological design

Science Process Skills:

Observing

Communicating

Collecting Data

Inferring

Predicting

Interpreting Data

Hypothesizing

Controlling Variables

Investigating

Activity Management:

Before attempting this activity, be sure

to conduct the Candle Flames activity.

Doing so will sharpen the observation

skills of the students. This is important

because, in this activity, students will

be observing the size, shape, and color

of a candle flame as it is falling.

Investigating candle flames in

microgravity can be done as either a

demonstration or an activity. If used as

a demonstration, only one candle drop

jar is necessary. If used as an activity,

one candle drop jar is needed for each

student group. Clear plastic food

storage jars are available at variety

Candle Flame in Microgravity

stores, but plastic peanut butter jars will work as

well. The jars should be 1 quart or half gallon size

(3 pound size if peanut butter jars are used). The

oxygen supply in smaller jars runs out too quickly

for proper observations.

The wood block and screws called for in the

materials and tools list can be replaced with a

lump of clay. Press the lump to the inside of the

A burning candle is encased by a clear plastic jar and

dropped for a study of flames in microgravity.

MATERIALS AND TOOLS

Clear plastic jar and lid (2 liter

volume)*

Wood block

Screws

Birthday candles

Matches

Drill and bit

Video camera and monitor

(optional)

Eye protection

* Empty 3-lb plastic peanut

butter jar can be used.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

130

jar lid and push the end of the candle into the

clay. It will probably be necessary to reform and/

or reposition the clay after a couple of drops. The

wood block and screws make a longlasting candle

drop jar.

If you are using wood blocks and screws, prepare

the candle drop jars by drilling a hole in the center

of the block to hold the end of the candle. Drill

two pilot holes into the wood for the screws.

Finally, drill holes through the plastic jar lid. With

the block in place, insert screws through the lid

holes and screw them into the wood block where

you drilled the pilot holes. The candle drop jar is

ready.

If you are using this as an activity, divide students

into groups of three. Save the student reader for

use after the experiment has been conducted.

Students will drop the candle at least three times

during their investigation. During the drops, there

are three jobs that must be performed. One

student will drop the candle, another will catch it,

and the third will observe the properties of the

candle flame as it falls. The jobs should be rotated

through the group so each student performs each

job once.

Since fire is used, be sure everyone working with

the activity wears eye protection. The activity

works best in a room that can be darkened.

Coordinate the observations of the student

groups so all are ready to drop the candle when

the lights are dimmed.

Students will observe that the first time a birthday

candle is lit, the flame is larger than when it is lit

again. This happens because the wick sticks out

farther from the wax on a new candle than it does

on a used candle. The excess is burned quickly

and the flame size diminishes slightly.

Assessment:

Use the student pages for assessment. For

additional work, have students actually build a

model of the microgravity experiment they are

instructed to design in the last step on the student

pages. The students can present their ideas to the

rest of the class and exhibit their device.

Extensions:

1. If videotape equipment is available, videotape

the candle flame during the drop. Use the

pause control during the playback to examine

the flame shape.

2. If a balcony is available, drop the jar from a

greater distance than is possible in a

classroom. Does the candle continue to burn

through the entire drop? For longer drops, it is

recommended that a catch basin be used to

catch the jar. Fill up a large box or plastic trash

can with Styrofoam packing material or loosely

crumpled plastic bags or newspaper.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

131

Microgravity experiments using drop towers and

Space Shuttle Orbiters have provided scientists

valuable insights on how things burn. In the

typical experiment, a flammable material, such as

a candle, is ignited by a hot wire. The ignition and

combustion process is recorded by movie

cameras and other data collection devices. Using

these devices, scientists have learned there are

significant differences between fires on Earth in

normal gravity and those in microgravity.

The sequence of pictures, at the bottom of this

page, illustrates a combustion experiment

conducted at the NASA Lewis Research Center

132 Meter Drop Tower. These pictures of a candle

Student Reader - 1

Candle Flames in Microgravity

flame were recorded during a 5-second drop

tower test. An electrically heated wire was used to

ignite the candle and then withdrawn 1 second

into the drop. As the pictures illustrate, the flame

stabilizes quickly, and its shape appears to be

constant throughout the remainder of the drop.

Instead of the typical teardrop shape seen on

Earth, the microgravity flams becomes spherical.

On Earth, the flame is drawn into a tip by the

rising hot gases. However, convection currents

are greatly reduced in microgravity. Fresh oxygen

is not being delivered to the candle by these

currents. Instead, oxygen works it way slowly to

the flame by the process of diffusion. Soon, the

flame temperature begins to drop because the

Candle flame test in the 132 Meter Drop Tower at the NASA Lewis Research Center
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

132

combustion is less vigorous. The lower

temperature slows down the melting and

vaporization of the candle wax. Candles onboard

the first United States Microgravity Laboratory,

launched in June 1992, burned from 45 seconds

to about 1 minute before being extinguished

because of the dropping temperature and

reduction of wax vapor.

Combustion studies in microgravity are

important to spacecraft safety. Unlike house fires

on Earth, you can not run outside of a space

station and wait for the fire department to arrive.

Fires have to be extinguished quickly and safely.

To do this it is essential to understand how fires

are ignited in microgravity and how they spread.

The goal is to make sure that a fire never gets

started.

In the absence of buoyancy-driven convection, as

in microgravity, the supply of oxygen and fuel

vapor to the flame is controlled by the much

slower process of molecular diffusion. Where

there is no “up” or “down,” the flame tends

toward sphericity. Heat lost to the top of the

candle causes the base of the flame to be

quenched, and only a portion of the sphere is

seen. The diminished supply of oxygen and fuel

causes the flame temperature to be lowered to the

point that little or no soot forms. It also causes

the flame to anchor far from the wick, so that the

burning rate (the amount of wax consumed per

unit time) is reduced.

Student Reader - 2
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

133

Candle Drop Team Members:

Candle Drop

Student Sheet - 1

Procedure:

1. Put on eye protection.

2. Light the candle and screw the jar on to the lid.

Observe the candle until it goes out.

3. Draw a picture of the shape of the candle flame

below.

What is the color of the flame?

Predict what you think will happen to the

candle flame when the candle is dropped.

4. Open the jar to release the bad air. Relight the

candle and screw the jar back on to the lid.

Have one team member hold the jar as high off

the floor as possible. On the count of three, the

jar is dropped to the floor where a second

team member is waiting to catch it. The third

member acts as the observer. Data are

recorded by the observer in the table on the

next page.

5. Repeat step 4 twice more but rotate the jobs so

each team member gets the chance to drop the

jar, catch the jar, and write down observations.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

134

Team Member: 1 2 3

Candle flame shape

Candle flame brightness

Candle flame color

Other observations

Candle Drop Data Table

Student Sheet - 2

What changes took place when the candle flame experienced microgravity?

Compare these changes to the candle flame that was not dropped.

Why do you think these changes took place?

Design a candle flame experiment that could be used on the International Space Station. Write out, on

another piece of paper, the experiment hypothesis and sketch the apparatus that will be needed. Write

a short paragraph describing the device, how it will work, and what safety procedures you would use.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

135

Objective:

• To demonstrate how atoms in a

solid arrange themselves.

Science Standards:

Science as Inquiry

Physical Science

- position and motion of objects

Unifying Concepts & Processes

Change, Constancy, &

Measurement

Science & Technology

- abilities of technological design

Science Process Skills:

Observing

Communicating

Collecting Data

Inferring

Predicting

Interpreting Data

Hypothesizing

Controlling Variables

I nvestigating

Activity Management:

The crystal model device described

here is best suited for use as a

classroom demonstration. It is a

vibrating platform that illustrates in

two dimensions the development of

crystal structure and defect

formation. BBs, representing atoms

of one kind, are placed into a shallow

pan which is vibrated at different

speeds. The amount of vibration at

any one time represents the heat

energy contained in the atoms.

Increasing the vibration rate

simulates heating of a solid material.

Crystallization Model

on

off

BBs on a vibrating plafform arrange themselves in patterns

similar to the atoms in solids.

Wood base and supports

Shallow pan

3 Small bungee cords

Small turnbuckle

Surplus 1 10 volt AC electric

motor

Motor shaft collar

Variable power transformer

Several hundred BBs

Hook and loop tape MATERIALS AND TOOLS

Eventually, the atoms begin to separate and move

chaotically. This simulates melting. Reducing the

amount of vibration brings theatoms back

together where they “bond” with each other. In

this demonstration, gravity pulls the BBs together

to simulate chemical bonds. By observing the

movement of BBs, a number of crystal defects

can be studied as they form and transform.

Because of movements in the pan, defects can

combine (annihilation) in such a way that the

ideal hexagonal structure is achieved and new

defects form.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

136

The model is viewed best with small groups of

students standing around the device. After the

solid “melts,” diminish the motor speed gradually

to see the ways the atoms organize themselves. It

is important that the platform be adjusted so it is

slightly out of level. That way, as the motor speed

diminishes the BBs will move to the low side of

the pan and begin organizing themselves. If this

does not happen, apply light finger pressure to

one side of the pan to lower it slightly. This will

not affect the vibration movements significantly.

While doing the demonstration, also stop the

vibration suddenly. This will simulate what

happens when molten material is quenched

(cooled rapidly) .

The motor collar required in the materials list is

available from a hardware store. The purpose of

the collar is to provide an offcenter weight to the

shaft of the motor. The set screw in the collar may

have to be replaced with a longer one so that it

reaches the motor shaft for proper tightening.

Constructing The

Vibrating Platform

Note: Specific sizes and part descriptions have

not been provided in the materials list because

they will depend upon the dimensions of the

surplus electric motor obtained. The motor

should be capable of several hundred revolutions

per minute.

1. Mount three vertical supports on to the wooden

base. They can be attached with corner braces

or by some other means. 2. Mount the surplus

motor to the bottom of the vibrating platform.

The specific mounting technique will depend

upon the motor. Some motors will feature

mounting screws. Otherwise, the motor may

have to be mounted with some sort of strap.

When mounting, the shaft of the motor should

be aligned parallel to the bottom of the

plafform.

3. Slip the collar over the shaft of the motor and

tighten the mounting screw to the shaft. See

the diagram below for how the shaft and collar

should look when the collar is attached properly.

Motor

Collar

Set Screw

Motor Shaft

4. Suspend the platform from the three vertical

supports with elastic shock (bungee) cords or

springs. Add a turnbuckle to one of the cords

for length adjustment. Shorten that cord an

amount equal to the length of the turnbuckle

so the platform hangs approximately level.

5. Using hook and loop tape, mount the pan on

the upper side of the vibrating plafform.

6. Place several hundred BBs in the pan. If the

BBs spread out evenly over the pan, lengthen

the turnbuckle slightly so the BBs tend to

accumulate along one side of the pan.

7. Turn on the motor by raising the voltage on the

variable transformer. If the device is adjusted

properly, the BBs will start dancing in the pan

in a representation of melting. Lower the

voltage slowly. The BBs will slow down and

begin to arrange themselves in a tight

hexagonal pattern. If you do not observe this

effect, adjust the leveling of the platform

slightly until you do. It may also be helpful to

adjust the position of the motor slightly.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

137

Conducting The Experiment

1. Turn up the voltage on the variable transformer

until the BBs are dancing about in the pan. This

represents melting of a solid.

2. Shut the variable transformer off. This represents rapid cooling of the liquid to a glassy

(amorphous) state. Observe and sketch the

pattern of the BBs and of the defects.

3. Turn up the voltage again and gradually reduce

the vibration until the BBs are moving slowly.

Observe how the BBs move and pack together.

Assessment:

Collect the student work sheets.

Extensions:

1. Obtain some mineral crystal samples and

examine them for defects. Most crystals will

have some visible defects. The defects will be

at a much larger scale than those illustrated in

the student reader. One defect that is easy to

find in the mineral quartz is color variations

due to the presence of impurities.

2. Investigate the topic of impurities deliberately

incorporated in crystals used to manufacture

computer chips. What do these defects do?

3. Design a crystal-growing experiment that could

be used on the International Space Station.

Conduct a ground-based version of that experiment. How would the experiment apparatus

have to be changed to work on the space

station?
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

138

Crystalline solids are substances whose

atoms or molecules are arranged into a fixed

pattern that repeats in three dimensions.

Crystalline materials generally begin as a fluid of

atoms or molecules in either the liquid or gaseous

state. As they change to the solid state, the atoms

or molecules join together in repeating patterns.

Materials that do not form these patterns are

called amorphous. Glass is a good example of an

amorphous material.

The usefulness of a crystal depends on its

structure. All crystalline materials have varying

degrees of defects. Defects can take many forms.

Gem-quality diamonds sometimes have small

inclusions of carbon (carbon spots) that diminish

their light refraction and thereby reduce their

value. In other crystalline materials, defects may

actually enhance value. Crystals used for solid

state electronics have impurities deliberately

introduced into their structure that are used to

control their electrical properties. Impurity atoms

may substitute for the normal atoms in a crystal’s

structure or may fit in the spaces within the

structure. Other defects include vacancies, where

atoms are simply missing from the structure, and

dislocations, in which a half plane of atoms is

missing. The important thing about crystal

defects is to be able to control their number and

distribution. Uncontrolled defects can result in

unreliable electronic properties or weaknesses in

structural metals.

Student Reader - 1

Crystallization

Sample Crystal Defects

The following diagrams show a magnified

view of an ideal two-dimensional crystalline

structure (hexagonal geometry) and a variety of

defects that the structure might have.

Ideal crystalline structure

Amorphous or glassy structure (when stationary)

or a liquid structure (when in motion)

Crystalline structure with surface (grain

boundary) defect
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

139

Many forces can affect the structure of a

crystal. One of the most important forces that can

influence the structure of a growing crystal is

gravity. Growing crystals in microgravity can

reduce gravity effects to produce crystals with

better defined properties. The information gained

by microgravity experiments can lead to improved

crystal processing on Earth.

The connection between the force of

gravity and the formation of defects varies from

very simple and straightforward to complicated

and nonintuitive. For example, mercury iodide

crystals can form from the vapor phase. However,

at the growth temperature (approximately 125° C)

the crystal structure is so weak that defects can

form just due to the weight of the crystal. On the

other hand, the relationship between residual fluid

flows caused by gravity and any resulting

crystalline defects is not well understood and may

be very complex.

Student Reader - 2

Crystalline structure with point defects (vacancies

and substitution impurities)

Crystalline structure (further magnified) with

interstitial defect and edge dislocations

Interstitial

Edge
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

140

Name: _________________________________

Based on your observations, describe and sketch

each crystallization stage shown with the model.

Melting:

Student Work Page - 1

Crystallization

Fast Cooling:

Slow Cooling:
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

141

Objective:

• To observe buoyancy-driven

covection currents that are created as

crystals grow in a crystal growing

solution.

Science Standards:

Science as Inquiry

Physical Science

- position and motion of objects

- properties of objects and materials

Unifying Concepts and Processes

Change, Constancy, & Measurement

Science Process Skills:

Observing

Communicating

Measuring

Collecting Data

Inferring

Predicting

Hypothesizing

Mathematics Standards:

Measurement

Activity Management:

This activity is best done as a

demonstration. While it is easy for

students to grow crystals by following

the directions, the success of observing

the density-driven convection currents

depends upon a very still environment.

The crystal-growing chamber should be

placed on a firmly mounted counter

where it will not be disturbed. The

convection currents are very sensitive

to vibrations. Place a slide projector on

one side of the chamber and direct the

Crystal Growth and BuoyancyDriven Convection Currents

Gravity-driven convection currents are created in a

crystal growth chamber by the interaction of the

growing crystal and the solution.

Aluminum potassium sulfate

AIK(SO4)212H20* (alum)

Square acrylic box**

Distilled water

Stirring rod

Monofilament fishing line

Silicone cement

Beaker

Slide projector

Projection screen

Eye protection

Hot plate

Thermometer Balance

*Refer to the chart for the amount

of alum needed for the capacity of

the growth chamber (bottle) you

use.

**Clear acrylic boxes, about 10x

10x13 cm, are available from craft

stores. Select a box that has no

optical distortions.

MATERIALS AND TOOLS
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

142

light from the projector through the growth

chamber so it casts a shadow on the wall behind.

If the wall behind the chamber is textured or a

dark color, tape a piece of white paper there to act

as a screen. Viewing may be improved by adding

dark paper shields around the screen to reduce

outside light falling on the screen. The projector

can be replaced by a clear lightbulb of about 100

to 150 watts that has a straight filament. Place the

bulb in a clip lamp light socket and aim the bulb

so the filament is pointing directly at the growth

chamber. This will make the bulb serve as a point

source of light so the shadows will be clear. Do

not use a reflective lamp shade with the light.

When preparing the crystal growing solution, be

sure to follow routine safety precautions such as

wearing eye protection. You can obtain this

chemical from school science supply companies

or even in food stores in the spice section. Alum

is used in pickling.

To produce large alum crystals, it is necessary to

obtain seed crystals first. This is accomplished by

dissolving some alum in a small amount of water

and setting it aside for a few days. Plan to do this

step several weeks before you will use the

demonstration with your students. To save time,

dissolve as much alum as you can in warm water.

This will produce a supersaturated solution when

the liquid cools and crystallization will start

shortly. After the seed crystals form (about 3-5

mm in size) pour the solution through some filter

paper or a paper towel to capture the seeds. Let

them dry before attaching the fishing line. In

attaching the line, simply place a dab of silicone

cement on a piece of paper and then touch the

end of a short length of monofilament fishing line

to the cement. Then, touch the same end of the

line to the crystal. Prepare several seed crystals in

this manner. When the cement dries, you will be

ready for the steps below.

You may discover mysterious variations in the

growth of the crystal over several days.

Remember, the amount of alum that can be

dissolved in a given quantity of water will vary

with the water’s temperature. Warm water can

hold more alum than cold water. If the airconditioning in a building is shut off for the

weekend, the temperature of the alum solution

will climb with the room’s temperature and some

or all of the crystal may dissolve back into the

water.

Procedure:

1. Prepare the crystal growth solution by dissolving powdered or crystalline alum in a beaker of

warm water. The amount of alum that can be

dissolved in the water depends upon the

amount of water used and its temperature.

Refer to the plot (Alum Solubility in Water) for

the quantity required.

2. When no more alum can be dissolved in the

water, transfer the solution to the growth

chamber acrylic box.

3. Punch or drill a small hole through the center

of the lid of the box. Thread the seed crystal

line through the hole and secure it in place with

a small amount of tape. Place the seed crystal

in the box and place the lid on the box at a 45

degree angle. This will expose the surface of

the solution to the outside air to promote

evaporation. It may be necessary to adjust the

length of the line so the seed crystal is several

centimeters above the bottom of the box.

4. Set the box aside in a place where it can be

observed for several days without being disturbed. If the crystal shouid disappear, dissolve

more alum into the solution and suspend a new

seed crystal. Eventually, growth will begin.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

143

5. Record the growth rate of the crystal by measuring it with a metric ruler. The crystal may

also be removed and its mass measured on a

balance.

6. Periodically observe the fluid flow associated

with the crystal’s growth by directing the light

beam of a slide projector through the box to a

projection screen. Observe plumes around the

shadow of the crystal. Convection currents in

the growth solution distort the light passing

through the growth solution. Refer to the

diagram at the beginning of this activity for

information on how the observation is set up.

Assessment:

Collect the student work sheets.

Extensions:

1. Try growing other crystals. Recipes for crystals

can be found in reference books on crystal

growing.

2. Collect natural crystals and observe their

surfaces and interiors (if transparent). Look for

uniformity of the crystals and for defects. Make

a list of different kinds of defects (fractures,

bubbles, inclusions, color variations, etc.).

Discuss what conditions must have existed in

nature at the time of the crystal’s formation or

after its formation to cause the defects.

3. Review scientific literature for results from

microgravity crystal-growing experiments.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

144

Student Reader - 1

Crystals can be grown using a variety of methods.

One of the simplest methods involves dissolving a

solid into a liquid. As the liquid evaporates, the

solid comes out of solution and forms a crystal

(or many crystals). This can be done with sugar

or salt or a variety of other compounds such as

alum (aluminum potassium sulfate), LAP (Larginine phosphate), or TGS (triglycine sulfate).

The usual procedure for growing crystals from a

solution is to create the solution first. In this

activity, a quantity of alum is dissolved into warm

water. Warm water was used to increase the

amount of alum that could be dissolved. You may

have observed this effect by stirring sugar into a

cup of hot coffee or tea. Hot liquids can dissolve

more sugar than cold liquids. After the alum was

dissolved, the solution was allowed to cool back

down to room temperature. As a result, the water

held more alum than it normally could at that

temperature. The solution was supersaturated. A

seed crystal was suspended in the solution and it

began to grow. The excess alum dissolved in the

water migrated to the crystal and was deposited

on its surface. Because the crystal growth

chamber was open to the surrounding air, the

solution began evaporating. This continued the

crystal growth process because the alum left over

from the evaporated water was deposited on the

crystal.

At first glance, the growth process of the alum

crystal looks very quiet and still. However,

examination of the solution and growing crystal

with light to produce shadows shows that

currents exist in the solution. These currents

become visible when light is projected through

them because the convection currents distort the

light rays, making them appear as dark plumes on

Crystal Growth and Buoyancy-Driven

Convection Currents

the screen. This image on the screen is called a

shadowgraph.

Where do these convection currents come from?

The answer has to do with the difference in the

amount of alum in solution near the growing

crystal compared with the solution near the wall

of the growth chamber. Except for near the

Water molecules in this diagram are represented by black

dots and the alum dissolved represented by the lighter dots.

Throughout most of the solution, the dots are randomly

mixed but, next to the crystal, the dots are mostly black.

This happens because the alum nearest the growing crystal

attaches to the crystal structure, leaving behind the water.

The remaining water is buoyant and rises while denser

water with more dissolved alum moves next to the crystal

to take its place.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

145

Student Reader - 2

crystal, the solution is homogeneous. This means

it has the same composition and density. The

solution near the crystal is another matter. As

each molecule of alum leaves the solution to

become deposited on the crystal’s surface, the

solution left behind becomes slightly less dense

than it was. The less dense solution is buoyant

and begins to rise in the chamber. More dense

solution moves closer to the crystal to take its

place. The alum in the replacement solution also

deposits on the crystal, causing this solution to

become less dense as well. This keeps the

convection current moving.

Microgravity scientists are interested in the

convection currents that form around a crystal

growing in solution. The currents may be

responsible for the formation of defects such as

liquid inclusions. These are small pockets of

liquid that are trapped inside the crystal. These

defects can degrade the performance of devices

made from these materials. The virtual absence of

buoyancy-driven convection in a microgravity

environment may result in far fewer inclusions

than in crystals grown on Earth. For this reason,

solution crystal growth has been an active area of

microgravity research.

Shadowgraph image of a growth plume

rising from a growing crystal.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

146

Crystal Growth and Buoyancy-Driven

Convection Currents

Name: _________________________________

1. In the box to the right, make a sketch of what you observed in the shadowgraph of a crystal growing

from solution.

2. Explain below what is happening.

Student Work Sheet- 1

Shadowgraph for growing alum crystal

3. In the box to the right, sketch what a shadowgraph should look like for a crystal that is dissolving

back into solution.

4. Explain your diagram below.

Shadowgraph for dissolving alum crystal
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

147

Student Work Sheet- 1

5. Draw a picture in the space to the right of what

you think the shadowgraph should look like for

a crystal grown from solution in a microgravity

environment.

6. Explain your picture below. Shadowgraph for alum crystal grown in

microgravity
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

148

Rapid Crystallization

Objective:

• To investigate the growth of

crystals under different temperature conditions.

Science Standards:

Science as Inquiry

Physical Science

- properties of objects and materials

Unifying Concepts and Processes

Change, Constancy, & Measurement

Science Process Skills:

Observing

Communicating

Measuring

Collecting Data

Inferring

Predicting

Interpreting Data

Controlling Variables

Investigating

Mathematics Standards:

Communication

Measurement

Activity Management:

This activity is best done with

cooperative learning groups of two

or three students. This will minimize

the number of heat packs that have

to be obtained. Heat packs are sold

at camping supply stores. It is

important to get the right kind of

pack. The pack, sold under different

names, consists of a plastic pouch

(approximately 9 by 12 centimeters

in size) containing a solution of

sodium acetate and water and a

small metal disk. When the disk

The rapid growth of crystals in a heat pack is

observed under different heating conditions.

Heat pack hand warmers

(1 or more per group)

Water boiler (an electric kitchen

hot pot can be used)

Styrofoam food tray

(1 per group)

Metric thermometer

(1 or more per group)

Observation and data table

(1 per student group)

Cooler

Clock or other timer

MATERIALS AND TOOLS

clicked or snapped, crystals begin to form and

heat is released. The pack can be reused by

reheating until all the crystals are dissolved.

Assemble all the materials needed for the activity

in sets for the number of student groups you

have. Prepare the heat packs by heating any that

are solidified until all the crystals dissolve.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

149

Allow one half of the packs to cool to room

temperature. Maintain the other packs at a

temperature of about 45°C. This can be done by

placing the packs in an insulated cooler with

some hot water until the packs are needed.

Before starting the experiment, discuss the data

collection procedure. To reduce heat conductivity

problems, heat packs are placed on the

Styrofoam food tray with the bulb of a

thermometer slipped between the pack and the

tray. Discuss with the students why the tray is

necessary and ask them where the best

placement of the bulb should be. Remind

students that the thermometer should be placed

the same way for each test. Give each student

group one student data sheet for each test to be

performed.

Begin with observation of the room temperature

pack first. The students should be prepared to

make observations immediately after the disk is

clicked. Complete crystallization should take less

than a minute. Since the crystallization process is

dramatic, demonstrate the clicking process with

another heat pack and pass it around for students

to feel. If you have some sort of video display

system, show crystallization on the television as it

is happening. This may help students focus on

the investigation when they start their own packs

crystallizing. Distribute the second pack after

observations of the first pack are complete.

Crystallization of the second pack will take several

minutes to complete.

Students will discover that heat packs with higher

initial temperatures will take longer to crystallize.

Crystals will be more defined than those forming

in packs with cooler initial starting temperatures.

Depending upon the initial temperature, crystals

may resemble needles or blades. Gravity will

influence their development. Crystals will settle to

the bottom of the pack and intermingle, causing

distortions. Crystals forming in an initially cool

heat packs will be needlelike but, because so

many form at once, the growth pattern will be

fan-shaped.

Use the questions below as a guide to discuss the

results of the investigation.

1. Is there any relationship between the initial

temperature of the pouch and the temperature

of the pouch during crystallization?

2. Is there a relationship between the initial

temperature of the pouch and the time it takes

for the pouch to completely solidify?

3. Do other materials, such as water, release heat

when they freeze?

Assessment:

Collect the student work sheets.

Extensions:

1. Discuss what might happen if the heat pack

were crystallized in microgravity. What effect

does gravity have? Hold the pack vertically with

the steel disk at the bottom and trigger the

solidification. Repeat with the disk at the top.

2. Try chilling a heat pack pouch in a freezer and

then triggering the solidification.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

150

Student Reader - 1

and Crystals

Crystals are solids composed of atoms, ions, or

molecules arranged in orderly patterns that repeat

in three dimensions. The geometric form of a

crystal visible to the naked eye can provide clues

to the arrangement inside. Many of the unique

properties of materials, such as strength and

ductility, are a consequence of crystalline

structure.

It is easy to get confused about the nature

of crystals because the word crystal is frequently

misused. For example, a crystal chandelier is not

crystal at all. Crystal chandeliers are made of

glass which is a solid material but does not have

a regular interior arrangement. Glass is called an

amorphous material because it does not have a

regular interior arrangement of atoms.

Scientists are very interested in growing

crystals in microgravity because gravity often

interferes with the crystalgrowing process,

leading to defects forming in the crystal structure.

The goal of growing crystals in microgravity is

not to develop crystal factories in space but to

better understand the crystal-growing process

and the effects that gravity can have on it.

In this activity, you will be investigating

crystal growth with a hand warmer. The hand

warmer consists of a plastic pouch filled with a

food-grade solution of sodium acetate and S

water. Also in the pouch is a small disk of

stainless steel.

Heat Pack

Snapping the disk triggers the crystallization

process. (The exact cause for this phenomena is

not well understood.) The pouch is designed so

that at room temperature the water contains many

more molecules of sodium acetate than would

normally dissolve at that temperature. This is

called a supersaturated solution. The solution

remains that way until it comes in contact with a

seed crystal or some way of rapidly introducing

energy into the solution which acts as a trigger

for the start of crystallization. Snapping the metal

disk inside the pouch delivers a sharp mechanical

energy input to the solution that triggers the

crystallization process. Crystallization takes place

so rapidly that the growth of crystals can easily

be observed. Heat is released during the

precipitation that maintains the pouch

temperature at about 54°C for about 30

minutes. This makes the pouch ideal for a

hand warmer. Furthermore, the pouch can

be reused by reheating and dissolving the

solid contents again.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

151

Student Work Sheet - 1

Heat Pack

Experiment

Data Sheet

Test number: ____________

Initial temperature of pouch: _______________

Temperature and time at

beginning of crystallization: ________________

Temperature and time at

end of crystallization: _____________________

Length of time for

complete crystallization: ___________________

Describe the crystals

(shape, growth rate, size, etc.)

Test number: ____________

Initial temperature of pouch: ______________

Temperature and time

at beginning of crystallization: _____________

Temperature and time at

end of crystallization:m __________________

Length of time for

complete crystallization: _________________

Describe the crystals

(shape, growth rate, size, etc.)

Team Member Names:

Sketch of Crystals

Sketch of Crystals
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

152

Microscopic Observation of

Crystal Growth

Objective:

• To observe crystal nucleation and

growth rate during directional

solidification .

Science Standards:

Science as Inquiry

Physical Science

- position and motion of objects

- properties of objects and materials

Unifying Concepts and Processes

Change, Constancy, & Measurement

Science Process Skills:

Observing

Communicating

Investigating

Activity Management

The mannite part of this activity

should be done as a demonstration,

using a microprojector or

microscope with a television system.

It is necessary to heat a small

quantity of crystalline mannite on a

glass slide to 168°C and observe its

recrystallization under magnification.

The instructions call for melting the

mannite twice and causing it to cool

at different rates. It is better to

prepare separate samples so they

can be compared to each other. Th~

slide that is cooled slowly can easily

be observed under magnification as

crystallizes. You may not have time

to observe the rapidly chilled sample

properly before crystallization is

complete. The end result, however,

A microprojector is used to observe crystal

growth.

Bismarck brown Y

Mannite (d-mannitol)

HOCH2(CHOH)4CH20H

Salol (Phenyl salicylate)

C13H10O3

Microprojector

Student microscopes (instead of

a microprojector)

Glass microscope slides with

cover glass

Ceramic bread-and-butter plate

Refrigerator

Hot plate or desktop coffee cup

warmer

Forceps

Dissecting needle

Spatula

Eye protection

MATERIALS AND TOOLS

will be quite apparent under magnification. If

students will be conducting the second part of

theactivity, it is suggested that you prepare

several sets of mannite slides so they may be
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

153

distributed for individual observations. The salol

observations are suitable for a demonstration, but

because of the lower melting temperature (48°C),

it is much safer for students to work with that the

mannite. A desktop coffee cup warmer is

sufficient for melting the salol on a glass slide.

Because of the recess of the warmer’s plate, it is

best to set several large metal washers on the

plate to raise its surface. The washers will

conduct the heat to the slide and make it easier to

pick up the heated slide with forceps. Point out to

the students that they should be careful when

heating the salol because overheating will cause

excessive evaporation and chemical odors, and

will increase the time it takes for the material to

cool enough for crystallization to occur. The slide

should be removed from the hot plate just as it

starts melting. The glass slide will retain enough

heat to complete the melting process.

Only a very small amount of bismarck brown is

needed for the last part of the activity with salol.

Only a few dozen grains are needed. Usually just

touching the spatula to the chemical causes

enough particles to cling to it. Gently tap the

spatula held over the melted salol to transfer the

particles. It will be easier to do this if the salol

slide is placed over a sheet of white paper. This

will make it easier to see that the particles have

landed in the salol.

If students are permitted to do individual studies,

go over the procedures while demonstrating

crystallization with the d-mannitol. Have students

practice sketching the crystallized mannitol

samples before they try sketching the salol.

Refer to the chemical notes below for safety

precautions required for this activity.

Notes On Chemicals Used:

Bismarok Brown Y

Bismarck brown is a stain used to dye bone

specimens for microscope slides. Because

bismarck brown is a stain, avoid getting it on

your fingers. Bismarck brown is water soluble.

Mannite (d-mannitol)

HOCH2(CHOH)4CH20H Mannite has a melting

point of approximately 168°C. It may be harmful if inhaled or swallowed. Wear eye protection

and gloves when handling this chemical.

Conduct the experiment in a well-ventilated

area.

Salol (phenyl salicylate)

C13H10O3

It has a melting point of 43° C. It may irritate

eyes. Wear eye protection.

Procedure: Observations of

Mannite

1. Place a small amount of mannite on a microscope slide and place the slide on a hot plate.

Raise the temperature of the hot plate until the

mannite melts. Be careful not to touch the hot

plate or heated slide. Handle the slide with

forceps.

2. After melting, cover the mannite with a cover

glass and place the slide on a ceramic breadand-butter plate that has been chilled in a

refrigerator. Permit the liquid mannite to

crystallize.

3. Observe the sample with a microprojector. Note

the size, shape, number, and boundaries of the

crystals.

4. Prepare a second slide, but place it immediately on the microprojector stage. Permit the

mannite to cool slowly. Again observe the size,

shape, and boundaries of the crystals. Mark

and save the two slides for comparison using

student microscopes. Forty power is sufficient

for comparison. Have the students make

sketches of the crystals on the two slides and

label them by cooling rate.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

154

Observations of Salol

5. Repeat the procedure for mannite (steps 1–4)

with the salol, but do not use glass cover slips.

Use a desktop coffee cup warmer to melt the

salol. It may be necessary to add a seed crystal

to the liquid on each slide to start the crystallization. Use a spatula to carry the seed to the

salol. If the seed melts, wait a moment and try

again when the liquid is a bit cooler. (If the

microprojector you use does not have heat

filters, the heat from the lamp may remelt the

salol before crystallization is completed.)

6. Prepare a new salol slide and place it on the

microprojector stage. Drop a tiny seed crystal

into the melt and observe the solid-liquid

interface.

7. Remelt the salol on the slide and sprinkle a tiny

amount of bismarck brown on the melt. Drop a

seed crystal into the melt and observe the

motion of the bismarck brown granules. The

granules will make the movements of the liquid

visible. Pay close attention to the granules near

the growing edges and points of the salol

crystals.

Assessment:

Collect the student data sheets.

Extensions:

1. Design a crystal-growing experiment that could

be flown in space. The experiment should be

self-contained and the only astronaut involvement that of turning a switch on and off.

2. Design a crystal-growing experiment for

spaceflight that requires astronaut observations and interpretations.

3. Research previous crystal-growing experiments in space and some of the potential

benefits researchers expect from space-grown

crystals.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

155

Student Reader - 1

Crystal Growth

Directional solidification refers to a process by

which a liquid is transformed (by freezing) into a

solid through the application of a temperature

gradient (a temperature difference over a

specified distance such as 1 0oC/cm) in which

heat is removed in one direction. The heat travels

down the temperature gradient from hot to cold.

A container of liquid will turn to a solid in the

direction the temperature is lowered. If this liquid

has a solute (something dissolved in the liquid)

present, typically some of the solute will be

rejected into the liquid ahead of the liquid/solid

interface. However, not all of the solute can be

contained in the solid as it forms; the remaining

solute is pushed back into the liquid near the

interface. This phenomenon has many important

consequences for the solid including how much

of the solute eventually ends up in the solid. The

concentration of solute in the solid can control

the electrical properties of semiconductors and

the mechanical and corrosion properties of

metals. As a result, solute rejection is studied

extensively in solidification experiments.

The rejected material tends to build up at

the interface (in the liquid) to form a layer rich in

solute. This experiment demonstrates what

happens when the growth rate is too fast and

solute in the enriched layer is trapped.

Fluid flow in the melt can also affect the

buildup of this enriched layer. On Earth, fluids that

expand become less dense. This causes a vertical

flow of liquid which will interfere with the

enriched layer next to the growing solid. In space,

by avoiding this fluid flow, a more uniform

enriched layer will be achieved. This, in turn, can

improve the uniformity with which the solute is

incorporated into the growing crystal.

Sample Microscope Sketches

Mannite Crystallization

Slow Cooling Fast Cooling
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

156

Name: ________________________________

1. Study the mannite crystallization slides. Sketch what you observe in the two circles below. Identify

the cooling rate for each slide and the magnification you used for your observatlons.

Mannite (d-Mannitol)

Cooling Rate: _______________________

Magnification: ______________________

Microscopic Observation of Crystals

Student Work Sheet - 1

Cooling Rate: _________________________

Magnification: ________________________

Describe below the difference between the two mannite samples.

How can you explain these differences?
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

157

Student Work Sheet - 2

2. Prepare the salol samples according to instructions provided by your teacher. Remember to wear

eye protection as you handle the chemical. Study the salol crystallization slides. Sketch what you

observe in the two circles below. Identify the cooling rate for each slide and the magnification you

used for your observations.

Cooling Rate: _____________________

Magnification: _____________________

Cooling Rate: _____________________

Magnification: _____________________

Salol (Phenyl Salicylate)

Describe below the difference between the two salol samples.

How can you explain these differences?
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

158

3. Prepare a third salol sample according to instructions provided by your teacher. Remember to wear

eye protection as you handle the chemical. Adjust the sample on the microscope stage so you can

observe the interface between the growing crystals and the melted chemicals. In particular, look at

what happens to the bismarck brown particles as the growing crystals contact them. Sketch what

you observe in the circle below.

Student Work Sheet - 3

Cooling Rate: ________________________

Magnification: _______________________

What happens to the resulting crystals when impurities (bismarck brown) exist in the melt?

Slow

What caused the circulation patterns of the liquid around the growing crystal faces? Do you think

these circulation patterns affect the atomic arrangements of the crystals? How?

How do you think the growth of the crystals would be affected by growing them in microgravity?
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

159

Zeolite Crystal Growth

Objective:

• To grow zeolite crystals and

investigate how gravity affects

their growth.

Science Standards:

Science as Inquiry

Physical Science

Unifying Concepts and Processes

Change, Constancy, & Measurement

Science in Personal and Social

Perspectives

Science Process Skills:

Observing

Communicating

Measuring

Collecting Data

Controlling Variables

Investigating

Mathematics Standards:

Measurement

Activity Management:

The preparation of zeolite crystals,

although not difficult, is an involved

process. A number of different

chemicals must be carefully weighed

and mixed. You may wish to prepare

the chemicals yourself or assign

some of your more advanced

students to the task. Refer to the

materials and tools list on the next

page for a detailed list of what is

required.

This activity involves maintaining a

hot water bath continuously for up to

8 days. If you do not have the

facilities to do this, you can conduct

Zeolite crystals are being grown in a hot water

bath.

the experiment for just the 0 and 1 TEA

(triethanolamine) samples described below.

Crystals may also be formed if the hot water bath

is turned off at the end of the school day and

turned on the succeeding day. Crystallization

times will vary under this circumstance, and close

monitoring of the formation of the crystalline

precipitate will be necessary.

Following the growth of zeolite crystals, small

samples can be distributed to student groups for

microscopic study.

Procedure:

1. While wearing hand and eye protection, weigh

0.15 grams of sodium hydroxide and place it in

a 60 ml, high-density polyethylene bottle. Add

60 ml of distilled water to the bottle and cap it.

Shake the bottle vigorously until the solids are

completely dissolved. Prepare a second bottle

identical to the first.

2. Add 3.50 grams of sodium
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

160

metasilicate to one of the bottles and again cap it

and shake it until all the solids are dissolved.

Mark this bottle “silica solution.” To the second

bottle, add 5.6 grams of sodium aluminate and

cap it and shake it until all the solids are

dissolved. Mark this bottle “alumina solution.”

3. Using a permanent marker pen, mark the four,

30 ml high-density polyethylene bottles with the

following identifications: 0 TEA, 1 TEA, 5 TEA, and

10 TEA.

Sodium aluminate NaAIO2

FW=81.97

Sodium metasilicate anhydrous,

purum, Na2

O3Si, FW=122.06

Sodium hydroxide pellets,

97+%, average composition

NaOH, FW=40

Triethanolamine (TEA), 98%

(HOHCH2)3N, FW=149.19

Distilled water

1000 ml Pyrex® glass beaker

Aluminum foil

Metric thermometer with range up

to 100°C

Laboratory hot plate

2-60 ml high-density polyethylene

bottles with caps

4-30 ml high-density polyethyene

bottles with caps

Plastic gloves

Goggles

Glass microscope slides

Permanent marker pen for

marking on bottles

Waterproof tape

Lead fishing sinkers

Tongs

Eyedropper

Optical microscope, 400X

MATERIALS AND TOOLS

4. Place 0.85 grams of TEA into the bottle marked

“1 TEA.” Place 4.27 grams of TEA into the

bottle marked “5 TEA.” Place 8.55 grams of

TEA into the bottle marked “10 TEA.” Do not

place any TEA into the bottle marked “0 TEA.”

5. Add 10 ml of the alumina solution to each of

the bottles. Also add 10 ml of the silica solution

to each bottle.

6. Cap each bottle tightly and shake vigorously.

Secure each cap with waterproof tape and tape

a lead sinker to the bottom of each bottle. The

sinker should weigh down the bottle so it will

be fully immersed in the hot water.

7. Prepare a hot water bath by placing approximately 800 ml of water in a 1000 ml Pyrexs

beaker. Place the four weighted bottles into the

beaker. The bottles should be covered by the

water. Cover the beaker with aluminum foil and

punch a small hole in the foil to permit a metric

thermometer to be inserted. Fix the thermometer in such a way as to prevent it from touching the bottom of the beaker. Place the beaker

on a hot plate and heat it to between 8$ and

95° C. It will be necessary to maintain this

temperature throughout the experiment.

Although the aluminum foil will reduce evaporation, it will be necessary to periodically add

hot (85 to 90° C) water to the beaker to keep

the bottles covered.

8. After 1 day of heating, remove the bottle

marked 0 TEA from the bath with a pair of

tongs. Using an eyedropper, take a small

sample of the white precipitate found on the

bottom of the bottle. Place the sample on a

glass microscope slide and examine for the

presence of crystals under various magnifications. Make sketches or photograph any

crystals found. Be sure to identify magnification of the sketches or photographs and estimate the actual sizes of the crystals. Determine

the geometric form of the crystals. Look for

crystals that have grown together.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

161

9. Repeat procedure 8 for the 1 TEA bottle after 2

days of heating. Repeat the procedure again for

the 5 TEA bottle after 5 days and for the 10 TEA

bottles after 8 days. Compare the size, shape,

and intergrowth of the crystals formed in each

of the bottles.

Assessment

Collect student sketches and written descriptions

of the zeolite crystals.

Extension:

1. Obtain zeolite filter granules from a pet shop.

The granules are used for filtering ammonia

from aquarium water. Set up a funnel with filter

paper and fill it with the granules. Slowly pour

a solution of water and household ammonia

(ammonia without lemon or other masking

scents) into the granules. Collect the liquid

below and compare the odor of the filtered

solution and the unfiltered solution. Try running

the filtered solution through a second time and

again compare the odors. Be sure to wear eye

protection.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

162

Zeolites are crystals made up of the elements

silicon, aluminum, and oxygen. The crystals

consist of alternating

arrays of silica (beach

sand, SiO2

) and alumina

(aluminum oxide, Al2

03)

and can take on many

geometric forms such as

cubes and tetrahedra.

Internally, zeolites are rigid

sponge-like structures with

uniform but very small

openings (e.g., 0.1 to 1.2

nanometers or 0.1 to 1.2 X

10-9 meters). Because of

this property, these

inorganic crystals are

sometimes called

“molecular sieves.” For

this reason, zeolites are

employed in a variety of

chemical processes. They

allow only molecules of

certain sizes to enter their

pores while keeping

molecules of larger sizes out. In a sense, zeolite

crystals act like a spaghetti strainer that permits

hot water to pass through while holding back the

spaghetti. As a result ot tnis filtering action,

zeolites enable chemists to manipulate molecules

and process them individually.

The many chemical applications for zeolite

crystals make them some of the most useful

inorganic materials in the world. They are used as

catalysts in a large number of chemical reactions.

(A catalyst is a material that has a pronounced

Student Reader- 1

Zeolites

effect on the speed of a chemical reaction without

being affected or consumed by the reaction.)

Scientists use zeolite

crystals to produce all

the world’s gasoline

though a chemical

process called catalytic

cracking. Zeolite crystals

are often used in

filtration systems for

large municipal

aquariums to remove

ammonia from the

water. Because they are

environmentally safe,

zeolites have been used

in laundry detergents to

remove magnesium and

calcium ions. This

greatly improves

detergent sudsing in

mineral-rich “hard”

water. Zeolites can also

function as filters for

removing low

concentrations of heavy metal ions, such as Hg,

Cd, and Pb, or radioactive materials from waste

waters.

Although scientists have found many beneficial

uses for zeolites, they have only an incomplete

understanding of how these crystals nucleate

(first form from solution) and grow (become

larger). When zeolites nucleate from a water

solution, their density (twice that of water) causes

them to sink to the bottom of the special

container (called an autoclave) they are growing
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

163

Student Reader- 2

in. This is a process called sedimentation, and it

causes the crystals to fall on top of each other. As

these crystals continue to grow after they have

settled, some merge to produce a large number of

small, intergrown zeolite crystals instead of

larger, separate crystals.

Zeolite crystal growth research in the

microgravity environment of Earth orbit is

expected to yield important information for

scientists that may enable them to produce better

zeolite crystals on Earth. In microgravity,

sedimentation is significantly reduced and so is

gravity-driven convection.

Zeolite crystals grown in microgravity are often of

better quality and larger in size than similar

crystals grown in control experiments on Earth.

Exactly how and why this happens is not fully

understood by scientists. Zeolite crystal growth

experiments on the Space Shuttle and on the

future International Space Station should provide

invaluable data on the nucleation and growth

process of zeolites. Such an understanding may

lead to new and more efficient uses of zeolite

crystals.
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

164

Name: _______________________

Instructions:

Observe through a microscope each zeolite crystal sample provided to you by your teacher. Sketch the

samples in the circles provided and write a brief description of what you see.

Sample 1

__________________ TEA

Sample age ________________ day(s)

Description:

Sample 2

__________________ TEA

Sample age ________________ day(s)

Description:

Microscopic Observation of

Zeolite Crystals

Student Work Sheet - 1

Magnification: ____________ X

Magnification: ____________ X
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

165

Student Work Sheet - 2

Sample 3

__________________ TEA

Sample age ________________ day(s)

Description

Sample 4

__________________ TEA

Sample age ________________ day(s)

Description

QUESTIONS:

1. What geometric form (crystal habit) did the zeolite crystals assume as they grew? Was there more

than one form present? How did the zeolite crystals appear when they grew into each other?

2. Can you detect any relationship between the length of time crystals were permitted to form, their

size and their geometric perfection?

3. Would additional growing time yield larger crystals? Why or why not?

Magnification: ____________ X

Magnification: ____________ X
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

167

NASA Resources for Educators

Regional Educator Resource Centers (RERCs) offer

more educators access to NASA educational materials. NASA

has formed partnerships with universities, museums, and other

educational institutions to serve as RERCs in many states. A

complete list of RERCs is available through CORE, or electronically via NASA Spacelink at http://spacelink.nasa.gov

NASA On-line Resources for Educators provide current

educational information and instructional resource materials to

teachers, faculty, and students. A wide range of information is

available, including science, mathematics, engineering, and

technology education lesson plans, historical information related to the aeronautics and space program, current status

reports on NASA projects, news releases, information on NASA

educational programs, useful software and graphics files. Educators and students can also use NASA resources as learning

tools to explore the Internet, accessing information about educational grants, interacting with other schools which are already

on-line, and participating in on-line interactive projects, communicating with NASA scientists, engineers, and other team members to experience the excitement of real NASA projects.

Access these resources through the NASA Education Home

Page: http://www.hq.nasa.gov/education

NASA Television (NTV)is the Agency's distribution system for

live and taped programs. It offers the public a front-row seat for

launches and missions, as well as informational and educational

programming, historical documentaries, and updates on the latest

developments in aeronautics and space science. NTV is transmitted

on the GE-2 satellite, Transponder 9C at 85 degrees West

longitude, vertical polarization, with a frequency of 3880 megahertz,

and audio of 6.8 megahertz.

Apart from live mission coverage, regular NASA Television

programming includes a Video File from noon to 1:00 pm, a NASA

Gallery File from 1:00 to 2:00 pm, and an Education File from 2:00

to 3:00 pm (all times Eastern). This sequence is repeated at

3:00 pm, 6:00 pm, and 9:00 pm, Monday through Friday. The NTV

Education File features programming for teachers and students on

science, mathematics, and technology. NASA Television

programming may be videotaped for later use.

For more information on NASA Television, contact:

NASA Headquarters, Code P-2, NASA TV, Washington, DC

20546-0001 Phone: (202) 358-3572

NTV Home Page: http://www.hq.nasa.gov/ntv.html

How to Access NASA's Education Materials and Services,

EP-1996-11-345-HQ This brochure serves as a guide to accessing a variety of NASA materials and services for educators.

Copies are available through the ERC network, or electronically

via NASA Spacelink. NASA Spacelink can be accessed at the

following address: http://spacelink.nasa.gov

AK, AZ, CA, HI, ID, MT, NV, OR,

UT, WA, WY

NASA Educator Resource Center

Mail Stop 253-2

NASA Ames Research Center

Moffett Field, CA 94035-1000

Phone: (415) 604-3574

CT, DE, DC, ME, MD, MA, NH,

NJ, NY, PA, RI, VT

NASA Educator Resource Laboratory

Mail Code 130.3

NASA Goddard Space Flight Center

Greenbelt, MD 20771-0001

Phone: (301) 286-8570

CO, KS, NE, NM, ND, OK, SD, TX

JSC Educator Resource Center

Space Center Houston

NASA Johnson Space Center

1601 NASA Road One

Houston, TX 77058

Phone: (281) 483-8696

FL, GA, PR, VI

NASA Educator Resource Laboratory

Mail Code ERL

NASA Kennedy Space Center

Kennedy Space Center, FL 32899-0001

Phone: (407) 867-4090

KY, NC, SC, VA, WV

Virginia Air and Space Museum

NASA Educator Resource Center for

NASA Langley Research Center

600 Settler's Landing Road

Hampton, VA 23669-4033

Phone: (757) 727-0900 x 757

IL, IN, MI, MN, OH, WI

NASA Educator Resource Center

Mail Stop 8-1

NASA Lewis Research Center

21000 Brookpark Road

Cleveland, OH 44135-3191

Phone: (216) 433-2017

AL, AR, IA, LA, MO,TN

U.S. Space and Rocket Center

NASA Educator Resource Center for

NASA Marshall Space Flight Center

P.O. Box 070015

Huntsville, AL 35807-7015

Phone: (205) 544-5812

MS

NASA Educator Resource Center

Building 1200

NASA John C. Stennis Space Center

Stennis Space Center, MS 39529-6000

Phone: (601) 688-3338

NASA Educator Resource Center

JPL Educational Outreach

Mail Stop CS-530

NASA Jet Propulsion Laboratory

4800 Oak Grove Drive

Pasadena, CA 91109-8099

Phone: (818) 354-6916

CA cities near the center

NASA Educator Resource Center for

NASA Dryden Flight Research Center

45108 N. 3rd Street East

Lancaster, CA 93535

Phone: (805) 948-7347

VA and MD's Eastern Shores

NASA Educator Resource Lab

Education Complex - Visitor Center

Building J-1

NASA Wallops Flight Facility

Wallops Island, VA 23337-5099

Phone: (757) 824-2297/2298

NASA’s Central Operation of Resources for Educators (CORE) was established for the national and international distribution of NASA-produced educational materials in

audiovisual format. Educators can obtain a catalogue and an

order form by one of the following methods:

• NASA CORE

Lorain County Joint Vocational School

15181 Route 58 South

Oberlin, OH 44074

• Phone (440) 774-1051, Ext. 249 or 293

• Fax (440) 774-2144

• E-mail nasaco@leeca8.leeca.ohio.gov

• Home Page: http://spacelink.nasa.gov/CORE

Educator Resource Center Network

To make additional information available to the education

community, the NASA Education Division has created the

NASA Educator Resource Center (ERC) network. ERCs contain a wealth of information for educators: publications, reference books, slide sets, audio cassettes, videotapes, telelecture

programs, computer programs, lesson plans, and teacher

guides with activities. Educators may preview, copy, or receive

NASA materials at these sites. Because each NASA Field

Center has its own areas of expertise, no two ERCs are exactly

alike. Phone calls are welcome if you are unable to visit the ERC

that serves your geographic area. A list of the centers and the

regions they serve includes:
Microgravity — A Teacher’s Guide with Activities in Science, Mathematics, and Technology,

EG-1997-08-110-HQ, Education Standards Grades 5–8 (∆), 9–12 (❏)

168

Educational Videotape

Educational Videotapes and slide sets are available

through the Educator Resource Center Network and

CORE (see listing on page 167).

Microgravity- Length 23:24

This video describes the restrictions that gravity

imposes on scientific experimentation and how they

can be greatly reduced in the exciting research

environment of the Space Shuttle and the International Space Station.

NASA publishes a variety of educational resources

suitable for classroom use. The following resources

specifically relate to microgravity and living, working,

and science research in the microgravity environment. Resources are available from different sources

as noted.

Slides

Microgravity Science - Grades: 8-12

This set of 24 slides illustrates the basic concepts of

microgravity and describes four areas of microgravity

research, including: biotechnology, combustion

science, fluid physics, and materials science. 1994

NASA Publications

NASA (1980), Materials Processing In Space: Early

Experiments, Scientific and Technical Information

Branch, NASA Headquarters, Washington, DC.

NASA (1982), Spacelab, EP-165, NASA

Headquarters, Washington, DC.

NASA (1976-Present), Spinoff. NASA Headquarters,

Washington, DC (annual publication).

NASA (1994), “Microgravity News,” Microgravity

Science Outreach, Mail Stop 359, NASA Langley

Research Center, Hampton, VA (quarterly newsletter)

NASA (1988), Science in Orbit - The Shuttle and

Spacelab Experience: 1981 -1986, NASA Marshall

Space Flight Center, Huntsville, AL.

NASA Educational Materials

Suggested Reading

Books

Faraday, M., (1988) The Chemical History of a

Candle, Chicago Review Press, Chicago, IL.

Halliday, D. & Resnick, R., (1988) Fundamentals of

Physics, John Wiley & Sons, Inc., New York, NY.

Holden, A. & Morrison, P., (1982), Crystals and

Crystal Growing, The MIT Press, Cambridge, MA.

Lyons, J., (1985), Fire, ScientificAmerican. Inc., New

York, NY.

American Institute of Aeronautics and Astronautics

(1981), Combustion Experiments in a Zero-gravity

Laboratory. New York, NY

Periodicals

Chandler, D., (1991), “Weightlessness and

Microgravity,” Physics Teacher, v29n5, pp.312-313.

Cornia, R., (1991), “The Science of Flames,” The

Science Teacher, v58n8, pp. 43-45.

Frazer, L., (1991), “Can People Survive in Space?,”

Ad Astra, v3n8, pp.14- 18

Howard, B., (1991), “The Light Stuff,” Omni, v14n2,

pp. 50-54.

Noland, D., (1990), “Zero-G Blues,” Discover. vl1n5,

pp. 7480.

Pool, R., (1989), “Zero Gravity Produces Weighty

Improvements,” Science, v246n4930, p.580.

Space World, (1988), “Mastering Microgravity,”

v7n295, p. 4.

Science News, (1989), “Chemistry: Making Bigger,

Better Crystals,” v136n22, p.349.

Science News, (1989), “Making Plastics in Galileo’s

Shadow,” v136n 18, p.286.

USRA Quarterly. (1992), “Can You Carry Your

Coffee Into Orbit?,” Winter-Spring.