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+-------------------------------------+--------------------------------+
| # Educational Product               |                                |
+-------------------------------------+--------------------------------+
| # Educators                         | # Grades                       |
|                                     |                                |
| **& Students**                      | **4-9**                        |
+-------------------------------------+--------------------------------+

EG-2004-0002-GRC/LaRC/JSC

**REDUCED GRAVITY:**

**Effects on the Human Body**

A Digital Learning Network Guide

Designed to Share the Vision of Space Exploration

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# 

**REDUCED GRAVITY:**

**Effects on the Human Body**

# 

# 

![](media/image2.png){width="3.25in" height="1.74375in"}

> ![](media/image3.wmf)
>
> **REDUCED GRAVITY: Effects on the Human Body** is available in
> electronic format through the NASA Digital Learning Network. This
> publication and other educational products may be accessed at the
> following address:
>
> http://education.nasa.gov/dln

# 

# REDUCED GRAVITY: Effects on the Human Body

A Digital Learning Network Guide\
Designed to Share the Vision of Space Exploration

![](media/image4.jpeg){width="1.5520833333333333in" height="1.21875in"}

This publication is in the public domain and is not protected

by copyright. Permission is not required for duplication.

# 

# 

# Table of Contents

Module Overview 2

Grade Level 2

Focus Question 2

Instructional Objectives 2

National Standards 2

Sequence of Events 2

NASA Education Evaluation Information System (NEEIS) Feedback Forms 2

National Standards 3

Pre-Conference Requirements 4

Online Assessment 4

Lesson Plan: Water Mystery, The 6

Videoconference Outline 9

Post-Conference Requirements 10

Lesson Plan: Bag of Bones 10

Online Assessment 15

NASA Education Evaluation Information System (NEEIS) Feedback Forms 15

Vocabulary 15

Resources 20

**Appendices**

Videoconference Rundown 21

NASA Event Guidelines 27

Audience Guidelines 27

Educator Event Checklist 28

Background Information 29

Contributors and Developers 39

# ![](media/image6.wmf) Module Overview

![](media/image7.wmf)

# 

**Grade Levels:** Grades 4-9 **Focus Question:** What are the effects of
long-term exposure to a reduced gravity environment on the human body?

# 

# Instructional Objectives:

-   Students will demonstrate an understanding of a reduced gravity
    environment and explain why research and countermeasures are needed
    for human exploration of space.

-   Students will make predictions and observe the effects of reduced
    gravity on the human body.

# National Standards: Science as Inquiry -- Content Standard A; Life Science -- Content Standard C; Number and Operations Mathematics Standard

# 

# Sequence of Events: 

> **Pre-Conference Requirements:** (one to two class periods)

1.  Online Assessment

2.  Lesson Plan: The Water Mystery

> *"Why doesn't the water flow out of the hole in the bottle?"* In this
> inquiry-based activity, students begin to investigate the effects of
> reduced gravity.
>
> **Videoconference:** (45-60 minutes)
>
> During the videoconference students will learn how long-term exposure
> to a reduced gravity environment can affect the human body. Students
> will participate in an activity to demonstrate these effects.
>
> **Post-Conference Requirements:** (one to two class periods)

1.  Lesson Plan: Bags of Bones

> On Earth, healthy bones are necessary for support, movement, and
> general good health. In space the lack of gravity can affect how bones
> are built and, as a result, how they work once an astronaut returns to
> Earth. Students will investigate bone loss and the effects of bone
> loss on astronauts and people on Earth.

2.  Online Assessment

**NASA Education Evaluation Information System (NEEIS) Feedback Forms:**
(4-5 minutes)

Educator and student feedback forms are available online for all DLN
events.

![](media/image8.wmf) **National Standards**

![](media/image9.wmf)

# National Science Education Standards

### Science as Inquiry - Content Standard A As a result of activities in grades 5-8, all students should develop:

-   Abilities necessary to do scientific inquiry.

-   Understandings about scientific inquiry.

### Life Science - Content Standard C As a result of their activities in grades 5-8, all students should develop an understanding of Structure and Function in Living Systems. Disease is a breakdown in structures or functions of an organism. 

## National Mathematics Standards

### Number and Operations Standard for Grades 6-8 In grades 6-8 all students should understand numbers, ways of representing numbers, relationships among numbers, and number systems. 

####### ![](media/image10.wmf)Pre-Conference Requirements

![](media/image11.wmf)

**1. Online Assessment**

> During the week before the event, students should complete the online
> pre-conference assessment. This short assessment will allow us to
> determine students' understanding of the topic prior to the NASA
> event.

#### Questions:

######### 

1.  What is microgravity?

2.  Reduced gravity is simulated on Earth by NASA with:

    a.  Neutral Buoyancy Laboratory -- Pool.

    b.  DC-9 Reduced Gravity Airplane.

    c.  Drop Towers.

    d.  All the above.

3.  Bone loss and muscle atrophy are effects of reduced gravity on the
    human body.\
    True\
    False

4.  How does fluid shift affect astronauts?

5.  Reduced gravity has no effect on the cardiovascular system.

> True\
> False

6.  List countermeasures to the effects of reduced gravity on the human
    body.

7.  How is the skeletal system affected by reduced gravity?

**Answers:**

1.  What is microgravity?

> **The term, *[microgravity]{.underline}* literally means *small
> gravity*, from the roots *mikros* (Greek) small + *gravity*. A reduced
> gravity environment (or μg), is defined as any environment where
> gravity levels are significantly reduced compared to those we
> experience at Earth's surface. We refer to Earth's surface environment
> as a one-gravity (1-g) environment.**

2.  Reduced gravity is simulated on Earth by NASA with:

    a.  Neutral Buoyancy Laboratory -- Pool.

    b.  DC-9 Reduced Gravity Airplane.

    c.  Drop Towers.

    d.  **All the above**.

3.  Bone loss and muscle atrophy are effects of reduced gravity on the
    human body.\
    **True**\
    False

4.  How does fluid shift affect astronauts?

***[Fluid shift]{.underline}* refers to the shift of fluids from the
lower to the upper body upon exposure to, or recovery from, reduced
gravity. As astronauts experience free fall, the fluids shift to the
upper part of the body and astronauts have "puffy" heads.**

5.  Reduced gravity has no effect on the cardiovascular system.

> True\
> **False**

6.  List countermeasures to the effects of reduced gravity on the human
    body.\
    **Exercise\
    Medications\
    Pre-Flight Training\
    Proper Nutrition**

7.  How is the skeletal system affected by reduced gravity?\
    **Loss of bone density**

**2. Pre-conference Activity Lesson Plan: The Water Mystery**

###### ![](media/image12.png){width="0.41338582677165353in" height="1.5in"}Materials:

-   1 pt plastic water bottle (the water bottle will last for\
    several tests). If a bottle is not available, use a paper or foam\
    cup. (The cup will last for one, possibly two tests.)

-   Nail

-   Pencil

-   Pitcher of water

-   Bucket (or conduct the experiment outside)

-   Paper Towels (for spills)

-   2 sheets of paper (of the same size)

-   Recording sheets for each group of students

-   A marble and a baseball

-   Masking tape

**Focus Question:** Why do we fall?

**Introduction:**

1.  In order for students to understand the effects of reduced gravity
    on the human body, they must first understand microgravity. Begin
    the class by discussing the Focus Question, *Why do we fall?* The
    answer is "Gravity."

2.  Next, ask your class: "What is gravity?"

3.  Have the students give real life examples of their experiences with
    gravity.

4.  Drop a marble and a baseball from the same height, releasing them at
    the same time. The students should observe that both hit the ground
    at the same time.

5.  Have a few of the students hold the ball and the marble, one in each
    hand. Ask them which is heavier. The students should conclude that
    the baseball is heavier. They should also conclude that mass plays
    no direct role in how fast things fall.

6.  Have several students hold two sheets of paper, one in each hand.
    They should conclude that the two pieces of paper are the same size
    and weight. Now crumple up one of the pieces of paper into a ball.
    The students should agree that the mass of the paper has not been
    changed during crumpling since nothing has been added to the paper.
    The other piece of paper should be left flat.

7.  Drop both pieces from the same height, releasing them both at the
    same time.

8.  Ask students why the crumpled up paper fell faster than the flat
    paper. Could it be due to gravity or to something else? Remind them
    about the baseball and the marble!

9.  Have the students observe that the two pieces of paper LOOK
    different. One is definitely WIDER than the other.

10. Now, discuss air resistance. The sheet of paper experienced a larger
    air resistance than the crumpled up piece of paper. Why?

11. Ask the students to imagine what would happen if they held their
    hand outside of the window of a moving car palm down. Then ask them
    what would happen if they held their hand palm to the wind. The
    palm-to-the-wind hand presents a BIGGER AREA for the wind to act
    against than the palm-down hand. So, area plays a role in air
    resistance. (Why did we not notice air resistance with the baseball
    and the marble? *Answer*: The weight of each was significantly
    larger than the air resistance acting on it. Such was NOT the case
    with the two pieces of paper.)

12. Conclude that the crumpled up paper had a smaller force of air
    resistance acting on it, because it presented a smaller surface area
    than the non-crumpled paper. Inform the students that, in a vacuum
    where there is no air resistance, both of these objects would fall
    at exactly the same rate.

**Body:** To be completed as a demo with the help of students.

1.  With a nail, punch a small hole close to the bottom of the bottle.
    Cover the hole with masking tape.

2.  Remove the cap from the water bottle.

3.  Place a bucket on the ground to catch the water that will drain from
    the bottle.

4.  While holding the bottle over the bucket, fill the bottle with
    water.

5.  Remove the tape and have the students use their recording sheets to
    record what happens.

6.  Tell the students to think about what happened and be prepared to
    discuss their thoughts.

7.  Place your thumb over the hole and refill the bottle.

8.  Hold the bottle up high then simply drop it into the bucket.

9.  Observe what happens to the stream of water when the bottle is
    released.

10. Repeat steps 7, 8, and 9. On the data sheet provided have the
    students record what happened to the water when the bottle was
    released.

**Closure:**

1.  As a class, discuss what happened when the bottle was released.

2.  Have the students explain all the reasons why they think the water
    remained in the bottle.

3.  Students should keep their Recording Sheets so they can report their
    results to the NASA researcher during the videoconferencing event.

#### Educator Explanation: Why it Works

Gravity is acting in both cases -- the case of the stationary bottle and
the case of the freely falling bottle. In the case of the stationary
bottle, the water is free to move but the bottle is not (because it is
being held). So, the water falls OUT of the bottle under the influence
of gravity. In the case if the falling bottle, the water and the bottle
are both free to move. In this case, THE WATER AND THE BOTTLE FALL
TOGETHER AT EXACTLY THE SAME RATE, as did the marble and the baseball.
Thus, there is no occasion for the water to flow out of the hole. If the
bottle were to fall in a room without any markings by which to judge its
motion, it would seem to a rider in the bottle as though gravity were
not acting at all. This condition is referred to as ZERO-G.

Adapted from: Microgravity: Earth and Space

An Educator's Guide with Activities in Technology, Science and
Mathematics

![](media/image13.png){width="1.0in" height="1.0in"}**Name
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_**

### The Water Mystery Recording Sheet *(to be completed and* 

### *brought to the videoconference)*

1\. Watch as your teacher covers the hole with tape, holds the bottle
over the bucket, fills the bottle with water, and removes the tape.

2\. Observe what happens.

3\. Record what happened in the box below.

4.  Watch as your teacher covers the hole with a thumb, fills the bottle
    with water again, and drops the bottle over the bucket.

5.  Observe what happened to the stream of water.

6.  Repeat steps 4-5.

7.  Record what happened in the box below.

![](media/image14.wmf)Videoconference Outline

![](media/image15.wmf)

Be sure to bring your students\' completed Water Mystery Recording
Sheets to the event. In addition, bring string and pens for a student
activity during the event. If you have two or three measuring tapes,
those can be used instead of string.

-   Microgravity

-   Effects of Reduced Gravity on the Human Body

-   Training For Reduced Gravity on Earth

-   Student Activity: Measuring the Effects of Reduced Gravity

-   Research and the Countermeasures on Fluid Shift; Cardiovascular,
    Neurovestibular, and Muscular Systems; and Skeletal Structure.

-   NASA Vision of Space Exploration

-   Careers

![](media/image16.png){width="1.3743055555555554in"
height="3.25in"}![](media/image17.wmf) Post-Conference Requirements

![](media/image18.wmf)

1\. Lesson Plan: Bag of Bones

**Materials:**

-   Corn Puff Cereal -- approx. 4.5 oz per group

-   Snack size zip lock bags (*Use small snack-sized bags; large ones
    take too long to fill and count.)* -- 5 per group

-   Heavy book -- one per group

-   Student Recording Sheet -- one per group

-   Broom and Dustpan for clean up

**Focus Questions:**

1.  Which minerals help to create strong bones?

2.  How can we create and maintain healthy bones?

3.  What is Osteoporosis?

**Introduction (Educators):**

1.  Discuss Osteoporosis and how good nutrition and exercise are
    essential for healthy bones.

2.  Aging and space flight have a similar effect on the human body; both
    may lead to **Osteoporosis** or a loss of bone mass. Osteoporosis
    makes bones weak and fragile, which can make it very easy to
    fracture or break a bone. In fact, many people do not realize that
    they have Osteoporosis at all until one of their bones fractures
    during a minor slip or fall. The activity you are about to complete
    investigates the effects of Osteoporosis in humans and provides
    important insight for people living on Earth and in space.

**Body:**

> **Getting Ready (Educators):**

3.  Divide the students into groups of 4. Give each group 5 plastic
    bags, a sufficient quantity of cereal, a permanent marker, a heavy
    textbook, and a recording sheet (shown on Page 14).

4.  Tell the students that each plastic bag represents a bone. The
    cereal inside the bone will represent the calcium and cells that
    make the bone strong. Pieces of cereal represent individual units of
    bone mass.

5.  Using a permanent marker, label the bags 1-5, with Bag 1
    representing a healthy bone on Earth.

## Building the First "Bone" (Students)

6.  Fill Bag 1 with enough cereal so that the bag is very full, leaving
    as little air as possible in the bag. The bag should not be so full
    that you cannot close it. Use whole pieces of cereal.

7.  Count the number of pieces of cereal you put into the bag, and
    record this number on your worksheet as Normal Bone Density.

8.  Close the bag, and seal it shut; otherwise you may wind up with a
    very big mess! Call Bag 1: 100% bone mass (normal bone); 0% bone
    loss.

### Building the Remaining 4 Bones (Students)

9.  To represent a bone that has lost mass through Osteoporosis, you now
    need to fill Bags 2 -- 5 with less and less cereal, or **bone mass
    density**, than Bag 1.

-   Bag 2: 90% of original bone mass; 10% of original bone loss

-   Bag 3: 80% of original bone mass; 20% of original bone loss

-   Bag 4: 65% of original bone mass; 35% of original bone loss

-   Bag 5: 50% of original bone mass; 50% of original bone loss

10. To calculate the amount of cereal in Bag 2, calculate 90% of the
    Normal Bone Density as shown below. Fill Bag 2 with this amount of
    cereal, which represents a loss of 10% of the bone mass.

11. Use a similar method to calculate 80%, 65%, and 50% of the Normal
    Bone Density, and fill Bags 3, 4, and 5 with these amounts. Record
    the count of "bone" placed in each bag on your recording sheet.

12. In building each bone, be certain that the air is squeezed out of
    the bag before sealing the bag shut. Otherwise, the air will act as
    a cushion and the demonstration will not work as intended.

### The Investigation (Students):

13. Now you are ready to witness the effects of a sudden force on normal
    bones and on weakened bones.

14. Place Bag 1 on a hard surface. The heavy textbook will provide for
    an unexpected force like a bump or a fall. Lift the book as high as
    possible and drop it onto the bag-bone. Turn the bag over and repeat
    the procedure, being careful to lift the book to the same height as
    before so that the impact force will remain constant.

15. Using the same height each time to maintain a constant impact force,
    repeat Step 14 for Bags 2, 3, 4 and 5.

16. What happened to the bones? Count the number of whole pieces of
    cereal left in each bag, and record this number on your student
    recording sheet. (Students should keep in mind that cereal pieces
    that have dust on them from other smashed pieces or only a tiny
    flake broken off should be counted as "unaffected" or whole.)

17. Determine the percentage of bone mass that was left unaffected by
    the impact. To calculate this percentage, use the formula:

18. Record the values on your Student Recording Sheet (Page 14).

19. Now, determine the percentage of bone mass that *[was]{.underline}*
    affected. To calculate this percentage, subtract the unaffected bone
    value percentage calculated in Steps 17-18 from 100.

100 ---

20. Record the values on your Student Recording Sheet (Page 14).

21. Discuss your results in your group and answer the questions on your
    Student Recording Sheet (Page 14).

**Closure (Educators):**

22. Use the questions on the student-recording sheet to help the class
    draw a conclusion.

    a.  What happened as the bone density decreased?

    b.  What prevented some bone from being affected by the sudden force
        of the book?

    c.  What do you think would happen if the plastic bag and cereal
        were a real bone and a sudden force, like a bump or fall, was
        applied to the bones?

    d.  How do you think bone loss can be prevented?

23. Through this experiment students should see why Osteoporosis could
    cause problems for astronauts -- and for people on Earth -- if this
    condition is left untreated. A bone left with mostly whole pieces of
    cereal is a bone slightly fractured but not broken clean through.
    The injury is minor and will heal quickly with proper care. The
    larger the percentage of affected bone, the greater the injury, and
    the longer the healing time. A bone with 100% damage is a bone
    fractured in two. This bone might need pins, rods, or even screws in
    addition to a cast in order to heal properly.

Now discuss the importance of proper diet and exercise. Everyone should
eat a proper diet and get plenty of exercise to maintain good health and
prevent Osteoporosis. A balanced diet rich in calcium and vitamin D,
exercise, and a lifestyle free of smoking and alcohol all help to
prevent or alleviate Osteoporosis. Regular bone density testing is often
necessary in older people, and, in some cases, medicine is used to help
maintain health.

But Osteoporosis also occurs in a reduced gravity environment, despite
diet and exercise. NASA is still trying to determine how to counter this
condition in astronauts for long-term stays in space. What are the
questions that the exercise raises about the possibilities of living on
a space station, or going to the Moon or Mars? Please discuss this
question as a class.

![](media/image19.png){width="0.6666666666666666in" height="1.0in"}

![](media/image20.jpeg){width="8.385416666666666in"
height="8.504861111111111in"}

**2. Online Assessment**

After completion of the Post-conference activity, have students complete
the online post-conference assessment. (These questions are the same
questions used in the pre-assessment.) The short assessment will help us
measure student learning and identify any changes that need to be made
in the Reduced Gravity educational module.

######### 

######## ![](media/image21.wmf)NASA Education Evaluation Information System (NEEIS) Feedback Forms

![](media/image22.wmf)

######## 

Please complete an online evaluation form to provide feedback on the
Reduced Gravity educational module.

[Educators]{.underline}
https://ehb2.gsfc.nasa.gov/edcats/nasa_wide/dln_educator.html

Feedback from several of your students (randomly selected) would also be
appreciated. [Students]{.underline}
https://ehb2.gsfc.nasa.gov/edcats/nasa_wide/dln_student_feedback.html

######## 

######## ![](media/image23.wmf) Vocabulary

![](media/image24.wmf)

The vocabulary list is provided for the educator's use in explaining
reduced gravity and the micro-G environment. Students should review the
terms and their definitions prior to participating in the
videoconferencing event.

**Bone Atrophy** - the weakening of bones as we get older or when bones
cannot develop normally.

**Cardiovascular System** - also called the circulatory system; includes
the heart and blood vessels, which take oxygen and nutrients in the
blood to all parts of the body.

**Countermeasures** - products or processes that may help astronauts
work and live in reduced gravity for long periods of time.

**Density** -- a measure of how much of a quantity is present in a
certain unit of space. Any physical quantity, such as mass, charge,
thermal energy, etc., when considered in a fluid or distributed state,
may be said to have an associated density. The most commonly used
density is **mass density**, *quantity of mass per unit volume of
space*, usually represented in MKS units as kg/m^3^.

**Drop Tower** -- a structure designed and built to allow vertical free
fall of a test object over some distance. Drop towers are usually built
*into* the earth or along the sides of cliffs, rather than above ground.
When test objects are in free fall, the objects (and everything in them)
are put into a condition of **zero-G** (zero gravity). Drop towers are
used to conduct experiments in which the effects of zero-G are
considered important. Typical drop times are usually no more than a few
seconds and may be extended (doubled) by firing the test object upward,
letting it rise then fall back down. A catch basin at the base of the
tower usually serves to capture the test object without producing impact
damage.

**Fluid Shift** - the shift of fluids from the lower to the upper body
upon exposure to, or recovery from, reduced gravity. This phenomenon
also occurs to a lesser extent during bed rest or exposure to lower body
negative pressure.

**Free Fall** - occurs when an object moves *unimpeded* in gravity. Many
people think free fall occurs when an object is released from some
height and simply allowed to fall "straight down." But an object thrown
or fired with a horizontal motion may also be in free fall if, after
released, it moves forward in a gravitational field. In this case, the
object does not fall "straight down," but moves in a forward direction
as it falls. Common examples of free fall with horizontal motion
include:

-   the flight of a bullet fired from a rifle;

-   the flight of a baseball released by the pitcher or hit by the
    batter; and

-   the motion of the Space Shuttle in orbit around the Earth.

Finally, a bullet fired vertically upward will also experience free
fall. It will decelerate, stop, and accelerate downward until it hits
the ground.

**g** -- the symbol associated with the acceleration of gravity that is
measured in MKS units of m/s^2^. (Example 1g) The standard value of g
(abbreviated G) refers to the gravitational acceleration at the surface
of the Earth: approximately 9.8 m/s^2^. Other accelerations may be
expressed in terms of this standard. Thus, we might speak of the pilot
at last year's Air Show who pulled 5-G's in some daring maneuver, or of
the astronauts aboard the Space Shuttle pulling a maximum of 3-G's
during throttle-up. Humans typically pass out at G levels of 6 to 7.

**Gravity** -- a distributed, spatial acceleration that is associated
with the presence of matter (mass). All of space is affected by the
presence of pieces of matter, whether that piece is a microscopic dust
mite or a super-giant star. Gravity exists both inside and outside of
any object possessing mass. The gravity at the boundary between the
interior of the object and open space is called the surface gravity. The
surface gravity of Earth is about 9.8 m/s^2^ and is often referred to as
"1-G." Many people erroneously think of gravity as a force. It is not a
force but an acceleration. At any location in a gravitational field, the
acceleration is the same for everyone. The force on each person is that
individual's mass multiplied by the local acceleration. Thus, an
elephant and a feather side-by-side in a gravitational field will both
fall at exactly the same rate. The force on each "adjusts" itself in
such a way that this is always true. Both Newton and Einstein considered
this property of gravitation to be one of its most mysterious.

**Gravity (gravitational) Field** -- a representation of the
acceleration of gravity due to the piece of matter at any and every
location (point). A test mass at any location in space will feel a
force-of-gravity equal to its own mass times the local gravitational
acceleration. This force-of-gravity is referred to as the **weight** of
the object at that location. When a test object falls freely in a
gravitational field, conditions aboard the test object very closely
approximate zero-G.

**Kinetic energy** -- the energy that an object possesses because of its
mass and its motion (speed). An object at rest can possess energy in
many forms, including heat energy or potential energy. But, unless an
object actually moves, it has no kinetic energy. Doubling the mass of a
moving object doubles its kinetic energy. Tripling its mass triples its
kinetic energy, and so on. But doubling speed increases kinetic energy,
not by a factor of 2, but by a factor of 4. Tripling an object's speed
increases its kinetic energy by a factor of 9. The usual expression for
kinetic energy is ½mv^2^ where **m** is mass and **v** is speed.

**Mass** -- a measure of an object's resistance to a change in its state
of rest or uniform motion. Applying a force to an object brings about a
change in motion. The greater the mass, the smaller the acceleration for
a given applied force. The relationship between force, mass, and
acceleration is given by one of Newton's Laws of Motion: **f = ma**,
where **f** is force, **m** is mass, and **a** is acceleration.

**Microgravity** -- *small gravity*, from the roots *mikros* (Greek)
small + *gravity*. A microgravity environment (or μg), is defined as any
environment where gravity levels are significantly reduced compared to
those we experience at Earth's surface. We refer to Earth's surface
environment as a one-gravity (1-g) environment. When an object falls
freely in a gravitational field, conditions aboard the object very
closely approximate zero-G.

**Muscle atrophy** - the wasting away or loss of muscle tissue because
of disease or lack of use.

**Muscular/skeletal system** - the system of muscles and bones that are
connected together to form a frame for our body. Muscles allow the
skeleton to move.

**Neurovestibular system** -- sensors that help people orient their body
position and balance. In reduced gravity, information sent to the brain
from the inner ear and other sensory organs conflicts with the
information that the brain has been accustomed to receiving on Earth.
This conflict results in disorientation and often space motion sickness.

**Nutrition** -- Nutrition is a term that applies to both the
[need]{.underline} to be fed and the [means]{.underline} to be fed.
Organisms have a *nutritional requirement*. For every organism, there is
a "proper diet," a balance of various essential nutrients to enable the
organism to function properly. Poor nutrition can result in fatigue or
illness, and improper nutrition can even result in death. Human
nutrition is being studied extensively as NASA prepares for multi-year,
piloted journeys to Mars and other destinations in the solar system.

**Orbit** -- the state of motion of an object in the gravitational field
of a planet or moon where the object (1) continuously falls toward the
planet or moon and (2) moves forward at a fast enough speed so that it
never hits the planet or moon. For example:

1.  Imagine simply dropping a golf ball. The ball accelerates toward the
    Earth along a vertical straight line and lands directly beneath the
    point from which it was released.

2.  Now imagine the ball being thrown horizontally forward at some
    speed. The ball accelerates toward the Earth along a curve and lands
    at a distant point.

3.  Now increase the horizontal speed of the thrown ball, and you will
    find that the forward distance will be increased.

4.  If the horizontal speed of the thrown ball becomes great enough, the
    ball will actually follow the curve of the Earth and, eventually,
    come back at you from behind, hitting you squarely in the head if
    you forget to duck! In this case, the time of flight of the ball
    from release to return is about 90 minutes. In reality, a ball
    thrown at the Earth's surface will be slowed by air resistance and
    so never complete the trip. But a ball thrown horizontally above the
    Earth's atmosphere will experience minimal air resistance and so
    will simply keep going around and around. Can you see why rockets
    are launched upward before turning to the East to enter their
    orbits?

**Osteoporosis** -- a medical term referring to a condition that
involves loss of bone mass and reduction in bone density. This condition
has been noted in astronauts who spend any time in orbit in a reduced
gravity environment, such as on the Space Shuttle or the International
Space Station. A few days in orbit produce a slight but measurable
effect. Recovery usually takes a few weeks, depending on the amount of
time spent in orbit, but is usually complete. Longer orbital stays
correspond to increased levels of Osteoporosis. Soviet cosmonauts who
have spent a year or longer in space have been known to display severe
Osteoporosis. At least partial recovery is possible in such extreme
cases, but individuals are often unable even to stand for a time upon
returning to Earth. Countermeasures to gravity-related changes in
humans, such as resistance exercises, are being researched to prevent
problems on multi-year journeys to Mars and other planets.

**Parabolic Aircraft** -- (NASA DC-9 "Weightless Wonder") a NASA
aircraft put into free fall along a parabolic path for purposes of
experimentation and/or astronaut training. When in a free fall
trajectory, the aircraft and everything and everyone on board are in
near zero-G until the pilot "pulls out" of the free fall.

**Potential Energy** - energy that an object possesses because of its
location. An object connected to the end of a compressed spring
possesses potential energy. Potential energy may be converted into
**kinetic energy** (the energy of motion) when the object is released to
move under the influence of the relaxing spring. The kinetic energy may
be converted into work if the moving object hits something such as a
nail and drives it into a piece of wood. In hitting the nail, the moving
object will lose most or all of its kinetic energy. Since energy can be
neither created nor destroyed (**Principle of Energy Conservation**), an
object gains one type of energy only at the expense of another type.

**Space Station** -- any permanent habitat in space where people live
and/or work. The International Space Station currently being built by
NASA and their international partners will see the arrival and departure
of many different astronauts who will use the station to conduct various
experiments. Their work will greatly expand human knowledge and pave the
way for continued human exploration of the Moon and Mars.

**Weight** -- the gravitational force exerted by an object within a
gravitational field. The object's mass times the local gravitational
acceleration is referred to as the weight of the object. The mass of an
object is usually a constant. But weight is subject to change, depending
on the local conditions of gravity. A person with100 kg of body mass
will weigh 980 N on Earth, 327 N on Mars, and 163 N on our Moon. On the
International Space Station, a person with 100 kg of mass will weigh 0
N.

######## ![](media/image25.wmf) Resources

![](media/image26.wmf)

**Microgravity: A Teacher's Guide with Activities in Science,
Mathematics, and Technology (Grades 5-12)**

This educator guide contains excellent background information
accompanied by classroom activities that enable students to experiment
with the forces and processes reduced gravity scientists are
investigating today.\
http://www.nasa.gov/audience/foreducators/topnav/materials/listbytype/Microgravity_Teachers_Guide.html

**Microgravity: Earth and Space (Grades 3-12)**

This NASA educator guide contains general information about reduced
gravity, classroom activities, and student worksheets. The activities
are meant to be completed by project teams and are grouped by grade
levels 3-5, 6-8, and 9-12.\
http://www.nasa.gov/audience/foreducators/9-12/features/F_Microgravity_Guide.html

**Inner Space in Outer Space (Grades 5-8)**

This educator guide allows educators and students to explore the same
aspects of human physiology studied on board the ISS: the systems of the
human body, how they work on Earth, and how they change in reduced
gravity.

http://virtualastronaut.jsc.nasa.gov/va/

**NASAexplores (Grades 5-8 and 9-12)**

This site includes an article called "Microgravity: Always a Bad Hair
Day" and a series of hands-on investigations that take an in-depth look
at reduced gravity.

[Inertial Balance]{.underline} **-** Learn how mass can be measured in
reduced gravity.

[Plant Growth In Reduced Gravity]{.underline} - Investigate the problems
of plant cultivation in space by simulating a reduced gravity
environment using plants attached to a slowly rotating clinostat.

[Feeling Faint?]{.underline} ***-*** Make and compare measurements of
heart rate and blood pressure from three body positions (sitting,
standing, and lying), which simulates how blood pressure is affected in
gravity and reduced gravity conditions.

<http://nasaexplores.msfc.nasa.gov/index.php>

**The Brain in Space (Grades 9-12)**

The study of the ways in which the body\'s brain, spinal cord, and
network of nerves control the activities of animals and humans is called
**neuroscience**. This guide targets a high school audience and provides
background material and activities related to NASA\'s Neurolab
research.\
http://www.nasa.gov/audience/foreducators/topnav/materials/listbytype/The.Brain.in.Space.html

**Appendices**

![](media/image27.wmf) **Videoconference Rundown**

![](media/image28.wmf)

+-------------------------------+--------------------------------------+
| **VIDEO (VISUAL)**            | **AUDIO (CONTENT)**                  |
+-------------------------------+--------------------------------------+
| TRT - Total estimated event   | **Pre-Event Slate and Word           |
| time is 50 minutes.           | Scramble**                           |
|                               |                                      |
| PPT 1 Reduced gravity Slate   | DLN site controlling the bridge      |
| and Word Scramble -- (file    |                                      |
| name: Wordscamble_PP01.ppt)   | Call in number: (add Number here)    |
|                               |                                      |
| **Call in 15 minutes before   | **NOTE:** Each site should introduce |
| schedule**                    | themselves for about 30 seconds for  |
|                               | voice activation switching, or split |
|                               | screen can be used to show all sites |
|                               | at once.                             |
+-------------------------------+--------------------------------------+
| **1:00**                      | **Intro with DLN Video Open**        |
+-------------------------------+--------------------------------------+
| **Video open DLN Video**      | ####### Host:                        |
|                               |                                      |
| **TRT : 30 VOT**              | ####### Hello. Welcome t             |
|                               | o the NASA Digital Learning Network. |
| PPT #2 Location graphic --    |                                      |
| (file name:                   | **I am Host and Center Name, Project |
| Location_PP02.ppt) if needed  | title.** With us today are Schools 1 |
|                               | and 2.                               |
|                               |                                      |
|                               | **Introduce SME.**                   |
+-------------------------------+--------------------------------------+
| **5:00**                      | **Introduce Microgravity**           |
+-------------------------------+--------------------------------------+
| **microgravity Jan Davis**    | **Host asks students:** What is      |
|                               | microgravity?***\                    |
| **TRT 1:22 VOT (being         | ***\                                 |
| edited??)**                   | **Host:** The term,                  |
|                               | ***microgravity*** literally means   |
| Outcue: "...floating when     | *small gravity*, from the roots      |
| really they are falling       | *mikros* (Greek) small + *gravity*.  |
|                               | A ***reduced gravity environment***  |
| > **Or Free Falling Clip**    | (or μg), is defined as any           |
|                               | environment where gravity levels are |
| PowerPoint Slides, PPT4       | significantly reduced compared to    |
|                               | those we experience at Earth's       |
| -   Orbit.ppt - series of     | surface. We refer to Earth's surface |
|     orbit slides to show free | environment as a one-gravity (1-g)   |
|     fall                      | environment.                         |
|                               |                                      |
|                               | **Host to SME:** So if there is a    |
|                               | small amount of gravity in space,    |
|                               | why do the astronauts float?         |
|                               |                                      |
|                               | **SME:** Free Falling                |
|                               |                                      |
|                               | -   Orbit slides to help explain     |
|                               |     concept                          |
|                               |                                      |
|                               | -   Video (free falling or           |
|                               |     microgravity)                    |
|                               |                                      |
|                               | **Host**: When you go home tonight   |
|                               | you can tell your family that the    |
|                               | astronauts are not floating in space |
|                               | they are really falling!             |
+-------------------------------+--------------------------------------+
| > **Rollercoaster Clip**      | **Host:** If students did            |
|                               | pre-activity, ask the following:     |
|                               |                                      |
|                               | -   What did you observe during the  |
|                               |     Water Mystery activity?          |
|                               |                                      |
|                               | -   What happened to the water?      |
|                               |                                      |
|                               | Elicit student responses: **Water    |
|                               | stays in bottle as the bottle and    |
|                               | water fall. The water is in a state  |
|                               | of freefall just like the shuttle or |
|                               | orbiter.Host asks students:**        |
|                               |                                      |
|                               | **Host to Students:** How can you    |
|                               | experience microgravity on earth?    |
|                               |                                      |
|                               | (Background) Have you ever ridden on |
|                               | a roller coaster? If so, do you      |
|                               | remember how you felt on the first   |
|                               | big hill? You were in near free fall |
|                               | on that hill, and free fall          |
|                               | environments are micro-g             |
|                               | environments. In effect, gravity was |
|                               | "turned off" for you for a second or |
|                               | two! Did you feel different? If not, |
|                               | we had better check to see whether   |
|                               | or not you are really alive!         |
|                               |                                      |
|                               | Show Rollercoaster clip.             |
+-------------------------------+--------------------------------------+
| **2:00**                      | **Transition**                       |
+-------------------------------+--------------------------------------+
| PPT 11 Moon                   | **Host to students:** Now that you   |
|                               | understand the definition of         |
| PPT 12 Mars                   | microgravity, why do we need to      |
|                               | understand the effects of reduced    |
| PPT 13 ISS                    | gravity on the human body?           |
|                               |                                      |
|                               | Well it will take.....               |
|                               |                                      |
|                               | -   3-4 travel days to get to the    |
|                               |     Moon                             |
|                               |                                      |
|                               | -   About 8 months to get to Mars -- |
|                               |     about one year stay              |
|                               |                                      |
|                               | -   Long term stay on ISS currently  |
|                               |     -- max. 6 months currently       |
|                               |                                      |
|                               | -   Reduced gravity has affects on   |
|                               |     the human body                   |
|                               |                                      |
|                               | **Host to students:** You and        |
|                               | students your age could be the       |
|                               | astronauts that continue NASA's      |
|                               | exploration of space. But before     |
|                               | that happens, we need to prepare for |
|                               | protecting the human body for long   |
|                               | durations in space.                  |
+-------------------------------+--------------------------------------+
| **3:30**                      | **Training On Earth For MicroG**     |
+-------------------------------+--------------------------------------+
| **:30**                       | **Host asks students:** How do you   |
|                               | think we train astronauts for the    |
|                               | effects of reduced gravity here on   |
|                               | Earth?\                              |
|                               | **Answers:** Neutral Buoyancy Lab,   |
|                               | DC-9, Simulators, Gravity Room, Drop |
|                               | towers                               |
+-------------------------------+--------------------------------------+
| **1:00**                      | **NASA Drop Towers (2.2 Second Drop  |
|                               | Tower, Zero-G Facility)**            |
| PPT 3 ZeroG Research Facility |                                      |
| -- (file name:                | One way we simulate zero-g on Earth  |
| zerog_PP03.ppt) **\           | is Drop towers. These facilities are |
| **                            | non human aspects and used to test   |
|                               | research experiments the astronauts  |
|                               | will conduct in space. These ground  |
|                               | based tests provide a sample of what |
|                               | the astronauts can expect to happen  |
|                               | during the test sequence and provide |
|                               | a sample of the test results that    |
|                               | could be expected.                   |
|                               |                                      |
|                               | The Zero Gravity Research Facility   |
|                               | (Zero-G) provides a near weightless  |
|                               | or reduced gravity environment for   |
|                               | the duration of 5.18 seconds. This   |
|                               | is accomplished by allowing the      |
|                               | experiment vehicle to free fall a    |
|                               | distance of 132 meters.              |
|                               |                                      |
|                               | You know the experience you get when |
|                               | you ride on one of the drop rides at |
|                               | the amusement park? That is similar  |
|                               | to what the experimental package in  |
|                               | the drop tower experiences during    |
|                               | the drop process.                    |
|                               |                                      |
|                               | **(Background)\                      |
|                               | Zero G Facility** (BG material if    |
|                               | needed)                              |
|                               |                                      |
|                               | Operational Parameters               |
|                               |                                      |
|                               | -   Microgravity Duration: 5.18      |
|                               |     seconds                          |
|                               |                                      |
|                               | -   Gravitational Acceleration: \<   |
|                               |     0.00001g                         |
|                               |                                      |
|                               | -   Mean Deceleration: 35g           |
|                               |                                      |
|                               | -   Peak Deceleration: 65g           |
|                               |                                      |
|                               | -   Vacuum Level: 0.01 torr          |
|                               |                                      |
|                               | Experimental Packages                |
|                               |                                      |
|                               | -   Cylindrical, 1m diameter by 3.7m |
|                               |     tall                             |
|                               |                                      |
|                               | -   Gross Vehicle Weight 1130kg      |
|                               |                                      |
|                               | -   Experimental payload weight of   |
|                               |     up to 455kg                      |
|                               |                                      |
|                               | -   Experimental payload up to 1m in |
|                               |     diameter and 1.6m tall           |
|                               |                                      |
|                               | Now let's focus on how we get the    |
|                               | astronauts ready for zero-g. NASA    |
|                               | has unique facilities like: the      |
|                               | Neutral Buoyancy Lab and the DC9.    |
+-------------------------------+--------------------------------------+
| **1:00**                      | **Neutral Buoyancy Lab**             |
|                               |                                      |
| **Vocab: Neutral Bouyancy**   | **Relate info to kids:**             |
|                               |                                      |
| **VIDEO: Neutral Buoyancy Lab | -   202' long x 102' wide x 40' deep |
| (NBL)**                       |                                      |
|                               | -   6.2 million gallons of water     |
| **TRT 0:30 MOS**              |                                      |
|                               | -   Training for procedures, repair, |
|                               |     & experimentation in a simulated |
|                               |     microG environment.              |
|                               |                                      |
|                               | -   For every hour in a space walk   |
|                               |     we train 8 hours in the NBL.     |
|                               |                                      |
|                               | **Host**: Explain what Neutral       |
|                               | Buoyancy is.                         |
|                               |                                      |
|                               | -   **Positive** -- what happens     |
|                               |     when you throw a basketball in   |
|                               |     the water -- it floats that is   |
|                               |     example of Positive bouyancy     |
|                               |                                      |
|                               | -   **Negative** -- throw a brick in |
|                               |     water what will happen -- sink   |
|                               |     -- that is negative buoyancy     |
|                               |                                      |
|                               | -   **Neutral** -- stays in middle   |
|                               |     --add weights or remove around   |
|                               |     ankles of astronauts             |
+-------------------------------+--------------------------------------+
| **1:00**                      | **DC-9 Reduced Gravity Research      |
|                               | Plane**                              |
| **MPEG: DC parabola**         |                                      |
|                               | -   True 3-Dimensional "weightless"  |
| **TRT :30 MOS**               |     environment                      |
|                               |                                      |
|                               | -   Plane performs a series of       |
|                               |     45-degree angle climbs           |
|                               |     (parabola) descends creating     |
|                               |     reduced gravity conditions       |
|                               |     (freefall) for about 15-30       |
|                               |     seconds.                         |
|                               |                                      |
|                               | -   Don't worry! No one gets hurt    |
|                               |     because of padding inside the    |
|                               |     plane!                           |
|                               |                                      |
|                               | -   Nick-name is "the Weightless     |
|                               |     Wonder."                         |
|                               |                                      |
|                               | -   In one trip the plane performs   |
|                               |     30 parabolas. Imagine riding on  |
|                               |     30 rollercoaster rides in a row. |
|                               |     How would your stomach feel?     |
+-------------------------------+--------------------------------------+
| **15:00**                     | **Student Activity -- Fluid Shifts** |
+-------------------------------+--------------------------------------+
| **14:00**                     | **Host leads activity**              |
|                               |                                      |
| Note: Alternate way...        | **Transition: Now you know some of   |
| Students hold arm up only for | the ways that astronauts train for   |
| some amount of time. During   | the effects of reduced gravity here  |
| this time you can query       | on Earth. Let's do a quick           |
| students on what they think   | experiment to see how Reduced        |
| will happen. Even ask test    | Gravity affects your body. To do     |
| subject what they are         | this experiment, I need your help.   |
| experiencing.                 | (2 minutes)**                        |
|                               |                                      |
| This may take less time...    | -   Students will work in pairs.     |
|                               |     (Student A should be wearing     |
|                               |     shorts or pants, not a skirt.)   |
|                               |                                      |
|                               | -   Each pair needs a piece of       |
|                               |     string or a measuring tape.      |
|                               |                                      |
|                               | -   Student A will sit in a chair.   |
|                               |     Student B will measure the       |
|                               |     circumference of one of Student  |
|                               |     A's calves using string or a     |
|                               |     measuring tape. The largest part |
|                               |     of the calf should be measured.  |
|                               |     (If using a string, have the     |
|                               |     student put a mark using a pen   |
|                               |     or a pencil on the string.)      |
|                               |                                      |
|                               | -   Next Student A should lie on the |
|                               |     floor, raise that same leg up in |
|                               |     the air, and prop the leg        |
|                               |     against the chair.               |
|                               |                                      |
|                               | -   After 30 seconds, Student B      |
|                               |     should once again measure        |
|                               |     Student A's calf at the same     |
|                               |     spot.                            |
|                               |                                      |
|                               | -   Have Student Teams report their  |
|                               |     findings.                        |
|                               |                                      |
|                               | -   Follow up with questions.        |
|                               |                                      |
|                               | **Questions to students:** (answer   |
|                               | as a class)                          |
|                               |                                      |
|                               | -   Was there a difference in the    |
|                               |     two measurements?                |
|                               |                                      |
|                               | -   Which was greater? Leg down or   |
|                               |     up?                              |
|                               |                                      |
|                               | -   Can anyone tell me the reason    |
|                               |     for this? (fluid shift)          |
|                               |                                      |
|                               | **Host Asks the SME:**               |
|                               |                                      |
|                               | -   How does reduced gravity affect  |
|                               |     the human body?                  |
|                               |                                      |
|                               | A big problem is that a fluid shift  |
|                               | occurs. Just like the fluid in your  |
|                               | arm/leg is affected in our gravity   |
|                               | environment, a similar but more      |
|                               | serious fluid shift is happening in  |
|                               | microG.                              |
+-------------------------------+--------------------------------------+
| **1:00**                      | **Fluid Shift in MicroG**            |
|                               |                                      |
| **Vocab: Fluid Shift**        | **SME Asks students:** How much of   |
|                               | our body is made up of fluids?       |
| **MPEG Fluid Shift**          |                                      |
|                               | **Answer:** About 80% is fluid.      |
| **TRT :33 VOT**               |                                      |
|                               | **Question:** Why is fluid shift a   |
| Outcue:"...the birdlegs of    | problem for the body in microG?      |
| space"                        |                                      |
|                               | **Answer:**                          |
|                               |                                      |
|                               | -   Body thinks it has too much      |
|                               |     fluid and releases fluids --     |
|                               |     becoming dehydrated.             |
|                               |                                      |
|                               | -   Cardiovascular system is         |
|                               |     affected...                      |
|                               |                                      |
|                               | **Host or SME:** This videoclip will |
|                               | help explain what fluid shift is...  |
|                               |                                      |
|                               | Play Fluid Shift Video               |
+-------------------------------+--------------------------------------+
| **17:00**                     | **Body Systems**                     |
+-------------------------------+--------------------------------------+
| **2:00**                      | **Cardiovascular System**            |
|                               |                                      |
| **MPEG Cardiovascular         | Let's take a look at what is         |
| System**                      | happening with the cardiovascular    |
|                               | system...                            |
| **TRT 1:14 VOT**              |                                      |
|                               | **Question:** What are the effects   |
| Outcue:"...bodies get more    | on the cardiovascular system?        |
| fluid & manufacture more      |                                      |
| blood."                       | **Answer:**                          |
|                               |                                      |
|                               | -   Heart thinks we have too much    |
|                               |     blood so it produces less blood, |
|                               |     which leads to fainting and      |
|                               |     dizziness                        |
|                               |                                      |
|                               | -   Within two to three days of      |
|                               |     weightlessness, the body can     |
|                               |     lose as much as 22% of its blood |
|                               |     volume as a result of that       |
|                               |     errant message                   |
|                               |                                      |
|                               | -   Heart pumps less                 |
|                               |                                      |
|                               | -   Lower blood pressure             |
|                               |                                      |
|                               | -   Feel tired or lethargic          |
+-------------------------------+--------------------------------------+
| **1:00**                      | **Cardiovascular Countermeasure      |
|                               | Suggestions**                        |
| **Countermeasure:** Any       |                                      |
| solution, medication,         | **Question to students:** What do    |
| activity, or device that      | you think are some countermeasures   |
| eliminates or reduces the     | for reducing the effects of microG   |
| adverse effects of space [on  | on the body?                         |
| the human body.]{.underline}  |                                      |
|                               | **Answers:**                         |
|                               |                                      |
|                               | -   Isotonic saline "load" -- 960ml  |
|                               |     fluid consumed 2 hours before    |
|                               |     re-entry.                        |
|                               |                                      |
|                               | -   Anti-G-suit inflated to put      |
|                               |     pressure on the body to protect  |
|                               |     against blood pooling in the     |
|                               |     lower extremities.               |
|                               |                                      |
|                               | -   Liquid cooling Garment (LCG)     |
|                               |                                      |
|                               | -   Artificial Gravity               |
|                               |                                      |
|                               | -   Exercise, at least 2 hours every |
|                               |     day                              |
|                               |                                      |
|                               | -   Attach magnets to feet.          |
+-------------------------------+--------------------------------------+
| **5:00**                      | **Neurovestibular System**           |
|                               |                                      |
| **Vocab: Neurovestibular      | **Host to students:** Does anyone    |
| System**                      | know what the Neurovestibular System |
|                               | is? Let's complete a quick (2        |
| **MPEG Neurovestibular        | minute) experiment to see what the   |
| System**                      | Neurovestibular System controls.     |
|                               | Directions:                          |
| **TRT 1:32 VOT**              |                                      |
|                               | 1.  Have the students work in pairs. |
| Outcue:"...space motion       |                                      |
| sickness goes away"           | 2.  Student A is the spotter.        |
|                               |                                      |
|                               | 3.  Student B stands with their back |
|                               |     to Student A.                    |
|                               |                                      |
|                               | 4.  Have Student A hold out their    |
|                               |     arms---to make sure Student B    |
|                               |     does not fall.                   |
|                               |                                      |
|                               | 5.  Student B should extend their    |
|                               |     arms out straight in front,      |
|                               |     close their eyes, raise one knee |
|                               |     up as high as possible, and hold |
|                               |     it there for about 30 seconds.   |
|                               |                                      |
|                               | 6.  If time permits, have Students A |
|                               |     and B switch places.             |
|                               |                                      |
|                               | 7.  Students A and B should return   |
|                               |     to their seats.                  |
|                               |                                      |
|                               | **Question:** Now, who can tell me   |
|                               | what the Neurovestibular System      |
|                               | controls? balance                    |
|                               |                                      |
|                               | **Question:** How many of you have   |
|                               | ever spun around and around? Or      |
|                               | ridden a roller coaster that         |
|                               | corkscrewed or looped on the track?  |
|                               |                                      |
|                               | What did it feel like?               |
|                               |                                      |
|                               | Do you think the astronauts have     |
|                               | similar feelings?                    |
|                               |                                      |
|                               | **Answers:** A variety from students |
|                               |                                      |
|                               | **Question:** Can anyone tell me     |
|                               | which parts of the body control our  |
|                               | balance and body orientation?        |
|                               |                                      |
|                               | **Answer:**                          |
|                               |                                      |
|                               | -   Inner Ear                        |
|                               |                                      |
|                               | -   Eyes                             |
|                               |                                      |
|                               | -   Neurovestibular system           |
|                               |                                      |
|                               | Let's find out more about this       |
|                               | system of balance....                |
|                               |                                      |
|                               | Show Neurovestibular System          |
|                               | videoclip                            |
|                               |                                      |
|                               | **Summary of video:**                |
|                               |                                      |
|                               | -   Otolith moves to give sense of   |
|                               |     balance                          |
|                               |                                      |
|                               | -   Does not match what the eye      |
|                               |     detects                          |
|                               |                                      |
|                               | -   Results in disorientation        |
|                               |                                      |
|                               | -   Causes Vertigo                   |
|                               |                                      |
|                               | -   Motion sickness and ...vomiting! |
|                               |                                      |
|                               | It normally takes about 1½ days for  |
|                               | astronauts to adjust to space.       |
+-------------------------------+--------------------------------------+
| **2:00**                      | **Neurovestibular Countermeasure     |
|                               | Suggestions**                        |
| **Video: (to be added by      |                                      |
| JSC)**                        | **Question:** What are possible      |
|                               | countermeasures?                     |
| Shows inside of ISS mockup    |                                      |
| allowing for pointing out the | **Answer:**                          |
| lights in the ceiling, blue   |                                      |
| stripes on the floor, heating | -   Slowing down head movement       |
| vents on the floor, all       |                                      |
| wording on the walls written  | -   Take Dramamine (medicine that    |
| in the same direction, foot   |     helps with motion sickness)      |
| restraints down and handheld  |                                      |
| restraints up.                | -   Visual clues, light on top, blue |
|                               |     stripes on bottom for sense of   |
|                               |     UP and DOWN (**Hint:** Look up   |
|                               |     in your classroom? What is at    |
|                               |     the top?)                        |
|                               |                                      |
|                               | -   All writing in the same          |
|                               |     direction                        |
|                               |                                      |
|                               | -   Foot restraints DOWN, hand hold  |
|                               |     UP                               |
|                               |                                      |
|                               | -   Show video (to be added by JSC)  |
|                               |                                      |
|                               | **Actual                             |
|                               | experiments/countermeasures:**       |
|                               |                                      |
|                               | Reference in [Neurovestibular        |
|                               | Adaptation Team Strategic            |
|                               | Plan]{.underline} article            |
|                               |                                      |
|                               | -   Locomotion and visual acuity     |
|                               |     tests                            |
|                               |                                      |
|                               | -   Gaze stability assessments       |
|                               |                                      |
|                               | -   Artificial gravity               |
|                               |                                      |
|                               | Preflight orientation training       |
+-------------------------------+--------------------------------------+
| **2:00**                      | **Muscular-Skeletal**                |
|                               |                                      |
| **MPEG Muscular System**      | **SME or Host:** Who can tell me how |
|                               | the muscular-skeletal system is      |
|                               | affected in space?                   |
|                               |                                      |
|                               | Muscle Atrophy will result in:       |
|                               |                                      |
|                               | -   Weaker muscles. Less muscle      |
|                               |     mass.                            |
|                               |                                      |
|                               | -   Muscle mass can be reduced at a  |
|                               |     rate of as high as 5% a week     |
|                               |                                      |
|                               | Discuss how muscles work in the      |
|                               | human body using MPEGs.              |
+-------------------------------+--------------------------------------+
| **5:00**                      | **Muscular-Skeletal Countermeasure   |
|                               | Suggestions**                        |
| PPT Slide: Exercise Equipment |                                      |
| (to be furnished by LaRC)     | > **Host:** How can we make our      |
|                               | > muscles stronger in space?         |
| **Props: barbell, giant       | > Exercise                           |
| elastic band**                |                                      |
|                               | Then have students do a short        |
| **MPEG Skeletal System**      | activity while seated that           |
|                               | illustrates how muscles work (2      |
| **MPEG Muscle-Bone**          | minutes):                            |
|                               |                                      |
| **TRT ? VOT**                 | -   Hold your arms straight out in   |
|                               |     front of you and keep them       |
| **(Now being re-edited by     |     straight.                        |
| LaRC)**                       |                                      |
|                               | -   Close your fists tight.          |
|                               |                                      |
|                               | -   Open your fists and extend your  |
|                               |     fingers.                         |
|                               |                                      |
|                               | -   Close your fists tight.          |
|                               |                                      |
|                               | -   Open your fists and extend your  |
|                               |     fingers.                         |
|                               |                                      |
|                               | -   Now repeat this process, faster  |
|                               |     and faster, over and over and    |
|                               |     over again.                      |
|                               |                                      |
|                               | -   When your arms get tired, grasp  |
|                               |     your hands together and notice   |
|                               |     the strength that you still      |
|                               |     have.                            |
|                               |                                      |
|                               | -   Continue the forearm exercise.   |
|                               |     Are your arms tired?             |
|                               |                                      |
|                               | **SME:** What this activity is       |
|                               | demonstrating is that when you       |
|                               | exercise, you are not using all of   |
|                               | your muscles. When riding a bicycle  |
|                               | or using a treadmill, you are not    |
|                               | working all of your big muscles.     |
|                               | NASA's challenge is developing       |
|                               | exercise equipment that puts "work   |
|                               | loads" on all muscles.               |
|                               |                                      |
|                               | **Host Question to Students:** Does  |
|                               | anyone know what the skeletal system |
|                               | is? What is the purpose of bones?    |
|                               |                                      |
|                               | **Host to SME:** We know what will   |
|                               | happen to muscles in Reduced         |
|                               | Gravity. But what happens to your    |
|                               | bones?                               |
|                               |                                      |
|                               | **Question:** Have you or a friend   |
|                               | ever had an arm-leg in a cast? What  |
|                               | did it look like when you got the    |
|                               | cast off?                            |
|                               |                                      |
|                               | **Answers:** A variety from students |
|                               |                                      |
|                               | Explain bone loss.                   |
|                               |                                      |
|                               | (Background)                         |
|                               |                                      |
|                               | Bone Loss:                           |
|                               |                                      |
|                               | -   Osteo**clast** gets rid of old   |
|                               |     bone cells                       |
|                               |                                      |
|                               | -   Osteo**blast** builds new bone   |
|                               |     cells                            |
|                               |                                      |
|                               | -   Bones in space can atrophy at a  |
|                               |     rate of about 1% a month         |
|                               |                                      |
|                               | -   Research models suggest that the |
|                               |     total loss could reach 40% to    |
|                               |     60%                              |
|                               |                                      |
|                               | **\*\*Lead into post BONE activity,  |
|                               | which will help students understand  |
|                               | why we need countermeasures.**       |
+-------------------------------+--------------------------------------+
| **1:00**                      | **Vision for Space Exploration**     |
+-------------------------------+--------------------------------------+
| **VIDEO: Exploration PSA**    | **Host:** Why do we explore space?   |
|                               |                                      |
| **TRT :30**                   | **Host:** Watch this short video on  |
|                               | exploration.                         |
|                               |                                      |
|                               | Show Exploration PSA Video.          |
|                               |                                      |
|                               | **Host to Students:** Can you think  |
|                               | of any other explorers? You are our  |
|                               | next explorers. Some of you may even |
|                               | step foot on Mars. Others may be     |
|                               | engineers that make this possible.   |
|                               | Whatever you choose to do, there is  |
|                               | an entire galaxy to explore.         |
+-------------------------------+--------------------------------------+
| **3:00**                      | **Careers**                          |
+-------------------------------+--------------------------------------+
| **VIDEO: Profiles, Tim        | **Exercise Physiologist** - The      |
| Schukar**                     | Exercise Physiology Laboratory seeks |
|                               | to develop exercise countermeasures  |
| **TRT 1:00 VOT**              | that crew members can perform in     |
|                               | order to mitigate these reductions   |
|                               | in strength which may effect         |
|                               | in-flight and post flight            |
|                               | activities.                          |
|                               |                                      |
|                               | **Biomedical Engineer** --           |
|                               | Biomedical Engineers use engineering |
|                               | principles to solve health related   |
|                               | and medical problems. They conduct   |
|                               | research in conjunction with life    |
|                               | scientists, chemists, and medical    |
|                               | professionals to design medical      |
|                               | devices like artificial hearts,      |
|                               | pacemakers, dialysis machines, and   |
|                               | surgical lasers.                     |
|                               |                                      |
|                               | **Flight Surgeons** -- Responsible   |
|                               | for the health and medical           |
|                               | monitoring and training of the       |
|                               |                                      |
|                               | Astronaut crew.                      |
+-------------------------------+--------------------------------------+
| **2:30**                      | **Question and Answer**              |
+-------------------------------+--------------------------------------+
| **To Presenter at Host        | ####### Goodbye and Closing          |
| Center**                      |                                      |
|                               | **Question from Host to Students:**  |
| PP# NASA Meatball             | Who can name one thing you learned   |
|                               | during today's event?                |
| PP# DLN with Goodbye          |                                      |
|                               | -   Find something you love to do    |
|                               |                                      |
|                               | -   Become passionate about it       |
|                               |                                      |
|                               | -   Discover the possibilities       |
|                               |                                      |
|                               | -   Website to further exploration   |
|                               |                                      |
|                               | Goodbye and thank you.               |
+-------------------------------+--------------------------------------+

TRT = Total Run Time

MOS = German term meaning no sound

VOT = Voice on Tape

NAT = Natural background sounds

2:00, 10:00 etc = estimated allowable time for each section. Total time
60 minutes maximum.

**Bold Blue** for MPEGs

**Bold Green** for Video

**Bold Purple** for Props

**Back to Presenter** = used to indicate when to come back to presenter

CG = Computer Graphics for word-terms or names of hosts

Talking points for Host, Talent, Guest

PP# = listing order of PowerPoint slides and brief description

![](media/image29.wmf)**NASA Event Guidelines**

![](media/image30.wmf)

**1. Audience Guidelines**

Good classroom management is important for successful distance learning
events. Educators, please review the following points with your students
prior to the event:

-   Videoconferencing is a two-way event. Students and NASA presenters
    can see and hear one another.

-   Students are sometimes initially shy about responding to questions
    during a videoconference. Explain to the students that this is an
    interactive medium and that we encourage questions.

-   Questions can be handled in one of two ways:

    -   Educators may choose to moderate students' questions and
        answers.

    -   Educators may choose to furnish each student a sheet of paper
        with a number or letter of the alphabet printed on it---in a
        large font and in bold. When students have a question or want to
        respond to a question, they simply hold up the sheet of paper
        and wait to be recognized by the presenter.

-   Students should speak in a loud, clear voice. If a microphone is
    placed in a central location, instruct the students to walk up and
    speak into the microphone.

-   Students should remain quiet while others are talking. The
    microphones pick up background noise, and this can be very
    distracting.

-   Students are representing their schools; they should be on their
    best behavior.

```{=html}
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```
-   Students should be prepared to give brief presentations (depending
    upon module selected), ask questions, and respond to NASA
    presenters.

**2. Educator Event Checklist**

+----------+-----------------------------------------------------------+
| **Date   | **Pre--Conference Requirements**                          |
| Com      |                                                           |
| pleted** |                                                           |
+----------+-----------------------------------------------------------+
|          | 1.  Print a copy of the module.                           |
+----------+-----------------------------------------------------------+
|          | 2.  Have the students complete the online pre-assessment. |
+----------+-----------------------------------------------------------+
|          | 3.  Complete pre-conference lesson.                       |
+----------+-----------------------------------------------------------+
|          | 4.  Email questions for the presenter. This will help     |
|          |     focus the presentation on the group's specific needs. |
+----------+-----------------------------------------------------------+
|          | 5.  Review the Audience Guidelines.                       |
+----------+-----------------------------------------------------------+
|          | **Day of the Conference Requirements**                    |
+----------+-----------------------------------------------------------+
|          | 1.  The students will be asked to share the results from  |
|          |     their pre-conference lesson with the NASA             |
|          |     presenter(s).                                         |
+----------+-----------------------------------------------------------+
|          | 2.  Bring any materials to help support the student       |
|          |     presentations.                                        |
+----------+-----------------------------------------------------------+
|          | **Post--Conference Requirements**                         |
+----------+-----------------------------------------------------------+
|          | 1.  Complete the post--conference lesson.                 |
+----------+-----------------------------------------------------------+
|          | 2.  Have the students complete the online post-assessment |
|          |     to measure their knowledge of the subject.            |
+----------+-----------------------------------------------------------+
|          | 3.  Complete the event feedback forms.                    |
+----------+-----------------------------------------------------------+

![](media/image31.wmf) **Background Information**

![](media/image32.wmf)

**WHAT IS MICROGRAVITY?**

The term, ***microgravity*** literally means *small gravity*, from the
roots *mikros* (Greek) small + *gravity*. A reduced gravity environment
(or μg), is defined as any environment where gravity levels are lower
than those we experience at Earth's surface, which we refer to as a
one-gravity (1-g) environment.

**GRAVITY IN GENERAL**

Gravity is often thought of as a force, which is a common misnomer that
leads to confusion for students studying gravity in physics.

Gravity is ***acceleration*** -- which is exactly why it is so
mysterious. A small test object, placed near any mass anywhere in the
universe and left to its own accord, will accelerate toward that mass.
(More correctly, the two masses will accelerate toward each other.) We
usually say that the test mass is moving "under the influence of
gravity," although it would probably be more correct to say that its
movement shows the presence of gravity in its vicinity.

At the Earth's surface, the gravitational acceleration amounts to about
9.8 m/s^2^ (32 ft/s^2^). When the mass of an object (in kg) is
multiplied by the acceleration, we calculate the ***weight*** of the
object, which may be thought of as a force acting on the object (since,
by Newton's Second Law of Motion, a force is a mass times an
acceleration). But it is very important to remember that weight is a
*derived* quantity and is *different* for an elephant than for a
feather, while the acceleration of gravity *is the same for all*. Thus,
the elephant and the feather will fall at exactly the same rate, even
though the force of gravity on each is very different! This concept lies
at the heart of understanding zero-g and micro-g.

Your body is accustomed to a one-gravity (1 g) environment because you
have grown up and lived all your life in 1-g. Your bones, muscles,
heart, nervous system, etc., are all "tuned" to this level of gravity.
If gravity were suddenly to change, you would feel radically different.
How could you experience such a change? Well...have you ever ridden on a
roller coaster? If so, do you remember how you felt on the first big
hill? You were in near free fall on that hill, and free fall
environments are micro-g environments. In effect, gravity was "turned
off" for you for a second or two! Did you feel different? If not, we had
better check to see whether or not you are really alive!

![](media/image33.png){width="2.21875in" height="3.4375in"}We take
gravity for granted on Earth. You have probably heard the adage**,**
"What goes up, must come down**.**" And you have probably experienced
the effects of gravity when you have fallen off a bike or a snowboard.
We all expect a football or snowflake moving through the air to
eventually fall to the ground.

Sir Isaac Newton (1642-1727) correctly stated that gravity governs
motions of objects everywhere in the universe; and indeed it does!
Newton described ***gravity*** as an acceleration associated with the
presence of matter. If there is a large concentration of matter at some
location in space (a star or a planet) then there is gravity inside and
outside of the concentration, as well as at its surface. Newton
succeeded in writing a mathematical description of gravitation that
helped to enable the rise of the modern age of technology.

Newton also erroneously thought of gravity as a force of attraction. He
understood that this idea of a force of gravity introduced significant
problems into his overall theory, but he could find no way out.

The central problem is this: if gravity is a force, then it must be a
peculiar kind of force that is able to act *without anything having to
touch anything else* -- a force without contact, or *action at a
distance*. A force is a push or a pull. Imagine pushing or pulling
something without ever coming into contact with it! No rope, no chain,
no "hands on." Simply "will" the object to move. And your will must be
transmitted instantaneously (without any delay) across space.

For almost 300 years following Newton's great work, physicists wrestled
with this problem of action at a distance. Full resolution came in 1917,
when Dr. Albert Einstein published his paper on General Relativity,
essentially re-writing all of Newton's work. It is important to note
that Newton did not fail -- in fact, he had succeeded brilliantly for
his time. And Einstein gave him highest praises for what he had
accomplished**:**

"If I have seen further than others," he once said, "it is because I
stand on the shoulders of Newton."

But Newton lacked the knowledge that was yet to arise in the centuries
following his great work. Had he had that knowledge, there is no telling
how far he would have been able to go!

When conceptualized as a force, gravity becomes an attraction existing
between all pairs of masses everywhere throughout the universe.
Essentially, where there is mass, there is gravity. There is
gravitational attraction between every pair of stars that you see in the
night sky. There is gravitational attraction between the Earth and the
Moon, and between the Moon and the Sun. There is even gravitational
attraction between you and this page because both you and the page
possess mass and, therefore, gravity!

Well then, why don't you feel yourself being "pulled" toward the page?
The mass of the page is miniscule compared with the mass of the Earth:

-   The mass of the page might be all of one gram (1 gm). The mass of
    the Earth is 6,000,000,000,000,000,000,000,000,000 gm (that's 6
    followed 27 zeros!). Thus, the gravitational effects of the Earth
    versus those of the page occur on a ratio of
    6,000,000,000,000,000,000,000,000,000 to 1.

Because Earth is so massive, its attraction is much greater than the
attractions of other objects around us. Newton mathematically described
the attraction between two objects of masses m~1~ and m~2~ separated by
a distance r as shown in the box. Sir Henry Cavendish (1731-1810)
modified Newton's law to include a gravitational constant, thus
producing the familiar equation still in use today.

![](media/image34.png){width="5.995138888888889in"
height="2.326388888888889in"}

Newton's Law and Cavendish's modification tell us that the greater the
masses m1 and/or m2, the greater the attraction F between them. Doubling
one of the masses doubles the attraction. Tripling one of the masses
triples the attraction. Tripling both masses increases the attraction by
a factor of 9. And so on.

The law of gravitation also tells us that the farther apart the objects
are from one another, the less the attraction between them. Because the
separation appears in the denominator *and is squared*, we observe that
doubling the separation decreases the attraction by a factor of 4;
tripling the separation decreases the attraction by a factor of 9, and
so on. Such a law is called an *inverse-square law* and is a familiar
breed of law in many areas of physics!

With Newton's Law of Gravity in hand, you now possess the "machinery" to
determine how gravity changes as you move away from Earth's surface.
Recall that, when standing on Earth's surface at 1 gravity or 1 g, the
acceleration of an object toward the center of Earth is approximately
9.8 meters per second squared (m/s^2^) or 32 feet per second squared
(ft/s^2^). Your mass and this acceleration of gravity when multiplied
together determine your weight. Please remember that while your weight
is subject to change with local gravity, your mass is not. Your mass is
the measure of the total amount of "stuff" making you up, and you
neither gain nor loose "stuff" when you move about!

Earth's gravitational attraction is *reduced* via the inverse square law
when you move away from Earth. Let us represent the Earth's radius by a
capital "R." On Earth's surface, we will set R=1; we say that we are at
*one "Earth-radius"* from the center of our planet. If you now travel
out to a distance of two Earth-radii, that is, to R =2, Earth's
gravitational pull drops to ¼ of its value on Earth's surface. Thus, if
you weighed 120 pounds at R = 1, you will weigh 30 pounds at R = 2.

**ABOARD THE SPACE SHUTTLE -- LIFE IN MICRO-G**

At Space Shuttle altitude \[343 km (212 mi)\], the astronauts and the
Shuttle are still under the influence of about 0.9 of Earth's surface
gravity. They are falling towards Earth with an acceleration of about
8.8 m/s^2^.

![](media/image35.jpeg){width="6.750694444444444in"
height="3.1840277777777777in"}

Why doesn't the Shuttle simply fall back toward Earth? Because it is
traveling forward at just the right speed \[more than 27,000 km/h
(17,000 mph)\] while simultaneously falling towards Earth to avoid ever
hitting Earth. We say that the Shuttle is in ***orbit***. It is moving
along a trajectory *that follows the curvature of Earth*. Because the
Shuttle is in free fall while in orbit around Earth, a reduced gravity
environment is established everywhere aboard the Shuttle. Remember that
the condition of microgravity occurs throughout an object whenever an
object is in free fall.

Why is this so? Remember the elephant and the feather? Both fall at the
same rate when allowed to fall freely. Thus, the elephant sees the
feather always next to him, and the feather sees the elephant always
next to it. As far as either one of them is concerned, they might as
well both be at rest with respect to one another. But being at rest and
remaining at rest is only possible where there is no gravity. Thus, the
elephant and the feather are both entitled to imagine themselves in a
*gravity-free region of space*, and may continue doing so right up to
the time that they hit bottom. At the point of hitting bottom, we
graciously allow the curtain to close so as not to have to see all that
happens immediately after...!

You have no doubt heard that the astronauts can move freely in space
because they are so far from Earth that gravity has little effect, or
that there is no gravity. Now you know that is not true. The Shuttle and
the astronauts and everything else on board are constantly falling
toward the Earth with an acceleration of about 8.8 m/s^2^. Aboard the
Shuttle, in a condition matching a gravity-free region of space, the
astronauts are able to move about freely. In fact, their motions are
aptly described by Newton's First Law of Motion mentioned earlier.

It might be interesting to note how the Space Shuttle acquires its
enormous speed of 17,000 miles per hour in the first place. It does so
by using rocket engines that fire with millions of pounds of thrust
during launch, liftoff, and ascent above the Earth's atmosphere. The
vehicle initially ascends above the atmosphere to get above those
regions where atmospheric drag is a factor in flight. As it ascends it
turns eastward, toward the local horizontal and continues to accelerate
to orbit. Once the engines are off, the Shuttle actually begins to orbit
(i.e., to fall freely toward Earth while simultaneously moving around
Earth's curved surface) and there it remains, going 'round and 'round,
until the descent engines are fired, reducing the vehicle's speed and
allowing it to fall back to Earth and so descend to the surface.

Sir Isaac Newton explained how a satellite could be made to orbit Earth.
Newton argued that if you placed a cannon at the top of a very tall
mountain then fired a cannonball parallel to the ground, the ball would
move in an arc and fall to Earth because of the presence of gravity. If
you increased the speed of the cannonball, it would travel farther
before landing, the arc along which it traveled would flatten out. And
if the cannonball were fired with sufficiently high speed, then the arc
would flatten out to match the curvature of Earth's surface. The ball
would achieve a state of continuous free fall, or orbit; it would fall
*entirely around Earth*. Provided no force other than gravity acted on
the cannonball's motion, it would keep circling Earth in orbit.

How does it feel to be aboard the Space Shuttle while it is in orbit?
Well...remember the roller coaster we mentioned earlier? Imagine feeling
that first hill, not for just a couple of seconds, but continuously for
a week or two! You would eat, work, sleep, do everything that you had to
do while feeling like your stomach was somewhere in your chest cavity
and your head was trying to swell beyond its accustomed boundaries.
Obviously, careful accommodations are required for astronauts to live in
space without injuring themselves in an environment that is so radically
different!

Meals are eaten in micro-g much as they are eaten on Earth. Swallowing
is not affected by a reduction in gravity. Sleeping in micro-g is
affected. Since there is no up or down in micro-g (remember "up" and
"down" can only be defined in reference to local gravity), the
astronauts are free to sleep in any position. The only constraint is
that they must sleep in specially prepared sleeping bags Velcro-ed to
the Shuttle walls. Otherwise, they would "float" about and collide with
one another.

If you were aboard the Space Shuttle, your workday would consist of
conducting experiments, exercising, taking meals, enjoying rest periods,
and taking pictures with various types of cameras including the IMAX
camera. Once you became acclimated to your new environment (a process
that may take a day or so) you would find it an exhilarating experience
and very enjoyable.

What kinds of science could you conduct in a reduced gravity environment
that would be different from science done in normal gravity conditions?
You might explore various properties of materials, or the behavior of
living organisms such as fish or insects. You might also study the
effects of reduced gravity on human physiology, acquiring knowledge that
will be essential if we are ever to send humans to such distant places
as Mars.

Before moving on, let's look a little more closely at one of these areas
-- the area of metal alloying. If you were to melt two different metals
on Earth, then mix them to form a new metal or alloy, you would quickly
find that the process works only if both metals have similar densities.
The density of a material is a measure of how much mass the material has
packed in a convenient unit volume of space and is usually measured in
units of kg/m^3^.

On Earth, if two metals of significantly different density were mixed in
the molten state, the less dense metal would always float to the top
unless the metals were actively and continuously mixed. Italian salad
dressing does much the same thing after it has been shaken then set
aside. We say that the dressing "settles." This settling occurs because,
in gravity, the heavier fluid sinks below the lighter fluid forcing it
to "float to the top." In orbit, in a micro-g environment, the two
metals mix much more readily and stay mixed, allowing formation of
alloys which often display unique properties, i.e., properties not
available on Earth.

NASA scientists are conducting reduced gravity research in areas such as
biotechnology, combustion science, fluid physics, fundamental physics,
and materials science. Reduced gravity can help us learn more about how
free fall conditions affect our bodies. It also gives us unique
opportunities to investigate new materials such as alloys, crystals, and
medicines.

![](media/image2.png){width="3.875in"
height="2.3958333333333335in"}**How Do We Create Reduced Gravity on
Earth?**

Orbiting spacecraft provide the best laboratories for long periods of
reduced gravity research. Experiments lasting for more than two weeks
are possible with the Shuttle. On the International Space Station
experimentation time can be extended to months. An important advantage
of having longer periods of time available is that scientists have the
ability to conduct research as it is conducted on Earth. Experiments can
be performed multiple times with different parameters. Thus scientific
researchers will be able to gather comprehensive data.

On Earth, scientists and engineers also use drop towers, aircraft, and
rockets to achieve short periods of reduced gravity. Doing so provides
much shorter experiment times, but also affords much lower cost.
Everything in life is a trade-off of some kind!

Dropping a payload down a deep hole on Earth creates free fall
conditions within the payload for the duration of the fall. Researchers
at NASA and in other facilities around the world use drop towers and
drop tubes to create reduced gravity environments. NASA's John H. Glenn
Research Center in Cleveland, Ohio, has two drop facilities. The
132-meter (430-ft) drop tower creates a reduced gravity environment for
about 5.2 seconds, while the 24-meter (79-ft) drop tower provides 2.2
seconds of microgravity per drop.

Experiments in the 2.2-second Drop Tower are assembled on a drop frame
structure and enclosed in an aerodynamically shaped box called a drag
shield that protects the experiment. The drag shield/experiment assembly
is hoisted to the top of the tower and released. The entire assembly
falls freely in the open environment of the tower. The experiment is
isolated from aerodynamic drag because it is contained within the drag
shield but not attached to it. During the drop, the entire assembly
falls 24 meters, and the experiment freely falls a distance of 20 cm
(0.65 ft) within the drag shield.

The package is slowed and stopped by a 3-meter (10-ft) tall air bag.
Battery packs provide onboard power to the experiment. High-speed motion
picture cameras, video cameras, and onboard computers collect data for
the investigator. The 5.2-second Zero-Gravity Facility drops larger
packages in a deep vacuum chamber. The longest drop time (10 seconds) is
in Japan where a vertical mineshaft was converted to a 490-meter
(1,607.2-ft) drop facility.

![](media/image36.jpeg){width="2.2104166666666667in"
height="2.745138888888889in"} ![](media/image37.jpeg){width="3.53125in"
height="2.5833333333333335in"}

You can also create a reduced gravity environment in an airplane as it
flies in a roller coaster trajectory or parabolic path. NASA astronauts
train for orbital missions in a modified DC-9, also called the
Weightless Wonder! A typical flight lasting from 2 to 3 hours gives
crewmembers about forty 20-second periods of reduced gravity. The plane
does a series of pull-up and pushover segments as it moves along its
roller coaster path in the air to produce temporary free fall. While the
conditions of reduced gravity are limited in an airplane because of
turbulence and flight-control limitations, the advantage is that
researchers can ride along with their experiments.

Small sounding rockets are another way to create reduced gravity.
Sounding rockets experience free fall conditions for 6 to 7 minutes as
they follow suborbital parabolic paths. Free fall exists during the
rocket's coast above Earth's atmosphere, where it is free of drag.

Adapted from: Microgravity: Earth and Space

An Educator's Guide with Activities in Technology, Science and
Mathematics

![](media/image16.png){width="1.3743055555555554in"
height="3.25in"}EFFECT OF REDUCED GRAVITY ON BONES

Life in the reduced gravity environment of space brings many changes to
the human body. The loss of bone and muscle mass, change in cardiac
performance, variation in behavior, and body-wide alterations initiated
by a changing nervous system are some of the most apparent and
potentially detrimental effects of reduced gravity. Changes to bone are
particularly noticeable because they affect an astronaut\'s ability to
move and walk upon return to Earth\'s gravity.

**Structure and Function of Bone**

Bone is a living tissue. It is dynamic, responsive to disease and
injury, and self-repairing. Bone has both an organic component and an
inorganic component. The organic component is composed mainly of
collage, long chains of protein that intertwine in flexible, elastic
fibers. Hydroxyapatite, the inorganic component, is a calcium-rich
mineral that stiffens and strengthens the collagen. Together, the
interwoven organic and inorganic components of bone create a sturdy yet
flexible skeletal structure.

The body is constantly breaking down old bone, and replacing it with new
bone. Bone is formed by cells called osteoblasts. These cells lay down
new mineral along the surface of bone. Osteoclasts, large multinucleate
cells, break down old bone, and are in part responsible for releasing
calcium into the bloodstream. In a healthy individual on Earth, bone is
formed at the same rate at which it is broken down, so there is never an
overall loss of bone mass. This process changes as a person grows older,
or enters reduced gravity for an extended period of time.

On Earth, Bones Perform Four Basic Functions

-   **Mechanical support:** The skeleton supports soft tissue and the
    body\'s weight. Many bones also act as levers for muscles, enabling
    movement.

-   **Storage of essential nutrients:** Bone stores much of the calcium
    received from the diet. The calcium is stored in hydroxapatite (the
    principal bone salt which provides the compressional strength of
    vertebrate bone). Between meals, the body maintains a constant
    concentration of calcium by absorbing it from bone and releasing it
    into the bloodstream. This constant calcium level in the bloodstream
    allows proper neural muscular, and endocrine (hormone) functioning,
    as well as other cellular activities (e.g., blood clotting). From
    the bloodstream, different organs and systems of the body take up
    the calcium. When the body absorbs too much calcium from bones the
    skeleton can become thin and weak. Bone is also a good source of
    phosphate, hydrogen, potassium, and magnesium. Like calcium, these
    minerals are used by many systems of the body for a wide range of
    purposes.

-   **Production of blood:** In addition to essential minerals, bone is
    also the storage site of marrow. Marrow is important for the
    formation and development of red and white blood cells and
    platelets.

-   **Protection**: The skeleton houses and protects the brain, spinal
    column, and nerves. Many bones, especially the ribs, also protect
    the internal organs.

**Bone and Reduced gravity**

Some of the processes and functions of bones change after the astronaut
has lived in reduced gravity for several days. In space, the amount of
weight that bones must support is reduced to almost zero. At the same
time, many bones that aid in movement are no longer subjected to the
same stresses that they are subjected to on Earth. Over time, calcium
normally stored in the bones is broken down and released into the
bloodstream. The high amount of calcium found in astronaut\'s blood
during space flight (much higher than on Earth) reflects the decrease in
bone density, or bone mass. This drop in density, known as disuse
Osteoporosis, leaves bone weak and less able to support the body\'s
weight and movement upon return to Earth, putting the astronaut at a
higher risk or fracture.

This bone loss begins within the first few days in space. The most
severe loss occurs between the second and fifth months in space,
although the process continues throughout the entire time spent in
reduced gravity. Extended stays on Mir have resulted in losses of bone
mass of as much as 20%. Astronauts regain most of their bone mass in the
months following their return from space, but not all of it.

The exact mechanism that causes the loss of calcium in reduced gravity
is unknown. Many scientists believe that reduced gravity somehow causes
bone to break down at a much faster rate than it is built up. However,
the exact trigger for this rate change has not been found. Researchers
are currently pursuing multiple lines of research, including hormone
level, diet, and exercise, in order to determine exactly what causes
(and may control or prevent) Osteoporosis during space flight.

Another type of Osteoporosis is a problem on Earth. As we grow older,
the body begins to absorb bone much faster than it produces new bone.
This leads to a lowered bone density, the same effect that reduced
gravity has on astronauts. As a result, bones become more fragile and
are more susceptible to fractures, especially in the hip, spine, and
wrist. In many cases, people do not know that they have Osteoporosis
until their bones become so weak that an accidental bump or fall causes
a fracture. Just as astronauts eat a careful diet and get plenty of
special exercise in space to prevent disuse Osteoporosis, steps can be
taken to prevent Osteoporosis on Earth. A balanced diet rich in calcium
and vitamin D, exercise, a lifestyle free of smoking and alcohol, bone
density testing, and medication all prevent or alleviate Osteoporosis.

Information from: ***http://virtualastronaut.jsc.nasa.gov***

![](media/image38.wmf) **Contributors and Developers**

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**NASA Digital Learning Network**

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