PUBLIC AFFAIRS CONTACTS

                          For Information on the Space 
Shuttle

Ed Campion                      Policy/Management                 
202/358-1778
  Headquarters, Wash., DC

Rob Navias                     Mission Operations                 
713/483-5111
  Johnson Space Center,        Astronauts
  Houston

Bruce Buckingham               Launch Processing                  
407/867-2468
  Kennedy Space Center, FL     KSC Landing Information

June Malone                    External Tank/SRBs/SSMEs           
205/544-0034
  Marshall Space Flight
  Center, Huntsville, AL

Cam Martin                      DFRC Landing Information          
805/258-3448
  Dryden Flight Research Center, 
  Edwards, CA

                    For Information on STS-73 Experiments & 
Activities

Mike Braukus                   USML-2                           
202/358-1979
  Headquarters, Wash., DC

Terri Hudkins                  Education Experiments              
202/358-1977
  Headquarters, Wash., DC

                                         i

                                     CONTENTS

GENERAL BACKGROUND
General Release                                                              
1
Media Services Information                                                   
3
Quick-Look Facts                                                             
5
Shuttle Abort Modes                                                          
7
Orbital Events Summary                                                       
8
Summary Timeline                                                             
9
Crew Responsibilities                                                       
10
Payload and Vehicle Weights                                                 
11

CARGO BAY PAYLOADS & ACTIVITIES
United States Microgravity Laboratory-2 (USML-2)                            
13

IN-CABIN PAYLOADS
Education Experiments                                                       
41

STS-73 CREW BIOGRAPHIES
Kenneth D. Bowersox, Commander (CDR)                                        
42
Kent Rominger,  Pilot (PLT)                                                 
42
Kathryn Thornton, Payload Commander/Mission Specialist-3 
(MS-3)             43
Catherine Coleman, Mission Specialist-1 (MS-1)                              
43
Michael Lopez-Alegria, Mission Specialist-2 (MS-2)                          
44
Fred Leslie, Payload Specialist-1 (PS-1)                                    
44
Albert Sacco, Payload Specialist-3 (PS-2)                                   
44

                                     ii

Release:  95-152

SECOND FLIGHT OF UNITED STATES MICROGRAVITY LABORATORY 
HIGHLIGHTS SIXTH SHUTTLE MISSION OF 1995

     The second United States Microgravity Laboratory (USML-
2) Spacelab mission will be the centerpiece of the STS-73 
Space Shuttle flight in late September 1995.  The Orbiter 
Columbia's planned 16-day flight will continue a cooperative 
effort of the U.S. government, universities and industry to 
push back the frontiers of science and technology in 
"microgravity", the near-weightless environment of space.

     Combining the strengths of these different communities 
allows for more extensive ground-based research in 
preparation for flight, improved methods for microgravity 
experimentation, and a wider distribution of the knowledge 
gained in the process.  The involvement of U.S. industry 
also means that the results of both ground-based experiments 
and Shuttle operations can be "brought down to Earth" in a 
timely and practical manner.

     Leading the five-person STS-73 crew will be Mission 
Commander 
Kenneth D. Bowersox who will be making his third space 
flight.  Pilot for the mission is Kent Rominger making his 
first flight.  The three mission specialists for STS-73 are 
Kathryn Thornton, Payload Commander and Mission Specialist 3 
(MS3), making her fourth flight; Catherine Coleman, Mission 
Specialist 1 (MS1), making her first flight; and Michael 
Lopez-Alegria, Mission Specialist 2 (MS2) making his first 
flight.  Also aboard Columbia will be two payload 
specialists--Fred Leslie, Payload Specialist 1 (PS1), and 
Albert Sacco, Payload Specialist 2 (PS2), both of whom will 
be making their first space flight.

     Launch of Columbia on the STS-73 mission is currently 
scheduled for no earlier than September 28, 1995 at 9:35 
a.m. EDT.  The planned mission duration is 15 days, 21 hours 
and 54 minutes.  An on-time launch on September 28 would 
produce a landing at 7:30 a.m. EDT on October 14 at Kennedy 
Space Center's Shuttle Landing Facility.

     Some of the experiments being carried on the USML-2 
payload were suggested by the results of the first USML 
mission that flew aboard Columbia in 1992 during Mission 
STS-50.  The USML-1 mission provided new insights into 
theoretical models of fluid physics, the role of gravity in 
combustion and flame spreading, and how gravity affects the 
formation of semiconductor crystals.  Data collected from 
several protein crystals grown on USML-1 have enabled 
scientists to determine the molecular structures of those 
proteins.

     USML-2 builds on that foundation.  Technical knowledge 
gained has been incorporated into the mission plan to 
enhance procedures and operations.  Where possible, 
experiment teams have refined their hardware to increase 
scientific understanding of basic physical processes on 
Earth and in space, as well as to prepare for more advanced 
operations aboard the international Space Station and other 
future space programs.  

     The experiments being carried as part of the USML-2 
payload cover a variety of scientific disciplines including 
fluid physics, materials science, biotechnology and 
combustion science.  

     The fluid physics area is fundamental to many types of 
science, from the ways molten metals solidify and fuels 
burn, to the way planetary atmospheres operate.  In space, 
subtle and complex phenomena normally hidden by the stronger 
force of gravity can be revealed for detailed study.

     Materials science will increase insight into the 
relationships between the structure, processing and 
properties of materials.  Mixtures that separate on Earth 
because of different component densities can be evenly mixed 
and processed in microgravity.  This allows scientists to 
study the processing of such materials and to create 
advanced materials for study and comparison.  Without the 
pull of gravity and the associated convective flows, more 
perfect crystals can be produced, an advance many believe 
vital for creation of advanced computer chips and 
semiconductors.

     Biotechnology experiments will grow protein crystals in 
three different experiment facilities, attempting to produce 
crystals of sufficient size and perfection that scientists 
can determine their structure and how they form.  This 
approach is being pursued because of the promise it holds 
for the development of improved drugs.  Two other 
biotechnology experiments address the development of food 
crops with higher protein content and increased disease 
resistance.

     Combustion science will aid in understanding the way a 
fire starts and spreads.  Understanding the combustion 
process without the interference of gravity could lead to 
more efficient fuels and improved fire safety, both in space 
and on Earth.

     Also during the STS-73 mission, students at four sites 
will interact with Columbia's astronauts to discuss and 
compare onboard microgravity experiments with similar 
ground-based experiments.  The goal is to involve students 
as participants in Shuttle investigations in an effort to 
generate excitement in physical science and chemistry.

     STS-73 will be the 18th flight of Space Shuttle 
Columbia and the 72nd flight of the Space Shuttle system.

                               - end -

                         MEDIA SERVICES INFORMATION

                         MEDIA SERVICES INFORMATION

NASA Television Transmission

     NASA Television is available through the Spacenet-2 
satellite system, transponder 5, channel 9, at 69 degrees 
West longitude, frequency 3880.0 MHz, audio 6.8 Megahertz.

     The schedule for television transmissions from the 
Orbiter and for mission briefings will be available during 
the mission at Kennedy Space Center, FL; Marshall Space 
Flight Center, Huntsville, AL; Dryden Flight Research 
Center, Edwards, CA; Johnson Space Center, Houston; NASA 
Headquarters, Washington, DC.  The television schedule will 
be updated to reflect changes dictated by mission 
operations.

     Television schedules also may be obtained by calling 
COMSTOR 713/483-5817.  COMSTOR is a computer data base 
service requiring the use of a telephone modem.  A voice 
update of the television schedule is updated daily at noon 
Eastern time.

Status Reports

     Status reports on countdown and mission progress, on-
orbit activities and landing operations will be produced by 
the appropriate NASA newscenter.

Briefings

     A mission press briefing schedule will be issued prior 
to launch.  During the mission, status briefings by a Flight 
Director or Mission Operations representative and when 
appropriate, representatives from the payload team, will 
occur at least once per day.  The updated NASA television 
schedule will indicate when mission briefings are planned.

Access by Internet

     NASA press releases can be obtained automatically by 
sending an Internet electronic mail message to 
domo@hq.nasa.gov.  In the body of the message (not the 
subject line) users should type the words "subscribe press-
release" (no quotes).  The system will reply with a 
confirmation via E-mail of each subscription.  A second 
automatic message will include additional information on the 
service.

     Informational materials also will be available from a 
data repository known as an anonymous FTP (File Transfer 
Protocol) server at ftp.pao.hq.nasa.gov under the directory 
/pub/pao.  Users should log on with the user name 
"anonymous" (no quotes), then enter their E-mail address as 
the password.  Within the /pub/pao directory there will be a 
"readme.txt" file explaining the directory structure.

  The NASA public affairs homepage also is available via the 
Internet.  The page contains images, sound and text (press 
releases, press kits, fact sheets) to explain NASA 
activities.  It also has links to many other NASA pages.  
The URL is: http://www.nasa.gov/hqpao/hqpao_home.html.

     Pre-launch status reports from KSC are found under 
ftp.hq.nasa.gov/pub/pao/statrpt/ksc, and mission status 
reports can be found under 
ftp.hq.nasa.gov/pub/pao/statrpt/jsc.  Daily TV schedules can 
be found under ftp.hq.nasa.gov/pub/pao/statrpt/jsc/tvsked.

Access by fax

     An additional service known as fax-on-demand will 
enable users to access NASA informational materials from 
their fax machines.  Users calling (202) 358-3976 may follow 
a series of prompts and will automatically be faxed the most 
recent Headquarters news releases they request.

Access by CompuServe

     Users with CompuServe accounts can access NASA press 
releases by typing "GO NASA" (no quotes) and making a 
selection from the categories offered.

                                STS-73 QUICK LOOK

Launch Date/Site:            September 28, 1995/KSC Launch 
Pad 39-B
Launch Time:                 9:35 AM EDT
Launch Window:               2 hours, 30 minutes
Orbiter:                     Columbia (OV-102), 18th flight
Orbit Altitude/Inclination:   150 nautical miles/39 degrees
Mission Duration:            15 days, 21 hours, 54 minutes
Landing Date:                October 14, 1995
Landing Time:                7:30 AM EDT
Primary Landing Site:        Kennedy Space Center, FL
Abort Landing Sites:         Return to Launch Site - KSC
                             Transoceanic Abort Sites - Ben 
Guerir, Morocco
                             Moron, Spain, Zaragoza, Spain
                             Abort-Once Around - Edwards Air 
Force Base, CA

Crew:                   Ken Bowersox, Commander (CDR), Red 
Team
                        Kent Rominger, Pilot (PLT), Red Team
                        Catherine Coleman, Mission 
Specialist  (MS 1), Blue Team
                        Michael Lopez-Alegria, MS 2, Blue 
Team
                        Kathryn Thornton, MS 3, Red Team
                        Fred Leslie, Payload Specialist 1 
(PS 1), Blue Team
                        Albert Sacco, (PS 2), Red Team

EVA Crew Members:	Michael Lopez-Alegria (EV1), Catherine 
Coleman (EV2)

Cargo Bay Payloads:     United States Microgravity 
Laboratory - 2
                        OARE

Developmental Test Objectives/Detailed Supplementary 
Objectives
      DTO 301D:   Ascent Structural Capability Evaluation
      DTO 307D:   Entry Structural Capability
      DTO 312:           ET TPS Performance
      DTO 319D:    Shuttle/Payload Low Frequency Environment
      DTO 414:           APU Shutdown Test
      DTO 623:           Cabin Air Monitoring
      DTO 655:           Foot Restraint Evaluation
      DTO 667:           Portable In-Flight Landing 
Operations Trainer
      DTO 679:           Ku-Band Communications Adapter 
Demonstration
      DTO 805:           Crosswind Landing Performance
      DTO 913:           Microgravity Measuring Device 
Evaluation
      DTO 1121:    Ground-to-Air TV Demonstration
      DSO 487:           Immunological Assessment of Crew 
Members
      DSO 491:           Characterization of Microbial 
Transfer Among the Crew 
      DSO 603C:   Orthostatic Function During Entry, Landing 
and Egress
      DSO 604:    Visual Vestibular Integration as a 
Function of Adaptation
      DSO 605:    Postural Equilibrium Control During 
Landing/Egress
      DSO 611:        Air Monitoring Instrument Evaluation 
and Atmosphere Test
      DSO 621:         In-Flight Use of Florinef to Improve 
Orthostatic Intolerance
      DSO 624:         Pre and Postflight of 
Cardiorespiratory Response to Exercise
      DSO 626:         Cardiovascular and Cerebrovascular 
Response Before and 
                       After Flight
      DSO 802:         Educational Activities
      DSO 901:         Documentary Television
      DSO 902:         Documentary Motion Picture 
Photography
      DSO 903:         Documentary Still Photography
      DSO 904:         Assessment of Human Factors

SPACE SHUTTLE ABORT MODES

     The Space Shuttle launch abort philosophy aims toward 
safe and intact 
     recovery of the flight crew, orbiter and its payload.  
Abort modes for 
     STS-73 include:

       *    Abort-To-Orbit (ATO) -- Partial loss of main 
engine thrust late 
       enough to permit reaching a minimal 105-nautical mile 
orbit with the 
       orbital maneuvering system engines.

       *    Abort-Once-Around (AOA) -- Earlier main engine 
shutdown with the 
       capability to allow one orbit of the Earth before 
landing at the 
       Edwards Air Force Base, CA.

       *    TransAtlantic Abort Landing (TAL) -- Loss of one 
or more main 
       engines midway through powered flight would force a 
landing at either 
       Ben Guerir, Morocco; Moron, Spain; or Zaragoza, 
Spain.

       *    Return-To-Launch-Site (RTLS) -- Early shutdown 
of one or more 
       engines, and without enough energy to reach a TAL 
site, would result in 
       a pitch around 	and thrust back toward KSC until 
within gliding 
       distance of the Shuttle Landing Facility.

                        STS-73 ORBITAL EVENTS SUMMARY
                      (Based on a Sept. 28, 1995 Launch)

EVENT                         MET                  TIME OF 
DAY (EDT)

Launch                        0/00:00              9:35 AM, 
September 28

OMS-2                         0/00:43             10:18 AM, 
September 28

Spacelab Activation           0/02:10             11:41 AM, 
September 28

Crew News Conference          13/19:30            5:05 AM, 
October 12

FCS Checkout                  14/19:30            5:05 AM, 
October 13

Spacelab Deactivation         15/13:45            11:20 PM, 
October 13

Deorbit Burn                  15/20:54            6:30 AM, 
October 14

KSC Landing                   15/21:54            7:30 AM, 
October 14

                        MISSION SUMMARY TIMELINE

Flight Day One:
Launch/Ascent
OMS-2 Burn
Spacelab Activation
USML-2 Operations

Flight Days 2-14:
USML-2 Operations

Flight Day 12:
Educational TV event with
students in Bozeman, MT, and 
Las Cruces, NM

Flight Day 13:
Educational TV event with
students in Worcester, MA, and
Louisville, KY

Flight Day 15:
USML-2 Operations
Crew News Conference

Flight Day 16:
USML-2 Operations
Flight Control System Checkout
Reaction Control System Hot-Fire
Cabin Stow
Spacelab Deactivation

Flight Day 17:
Deorbit Prep
Deorbit Burn
Entry
KSC Landing

                        CREW RESPONSIBILITIES

Payloads                      Prime                         
Backup

USML-2                        Thornton, Coleman
                              Sacco, Leslie
DTO/DSOs

DTO 312                       Coleman, Lopez-Alegria 
DTO 623                       Rominger                      
Bowersox
DTO 655                       Thornton, Coleman, Sacco
DTO 667                       Rominger                      
Bowersox
DTO 679                       Bowersox, Lopez-Alegria       
Rominger
DTO 682                       Rominger, Lopez-Alegria       
Bowersox
DTO 913                       Rominger, Lopez-Alegria       
Bowersox
DSO 603C                      Thornton, Leslie, Sacco
DSO 604                       Rominger, Lopez-Alegria
DSO 605                       Bowersox
DSO 611                       Rominger, Lopez-Alegria
DSO 621                       Leslie
DSO 624                       Bowersox, Rominger
DSO 626                       Thornton, Sacco, Leslie
DSO 802                       Coleman, Sacco
DSO 901                       Rominger, Lopez-Alegria
DSO 902                       Rominger, Lopez-Alegria
DSO 903                       Rominger, Lopez-Alegria
     
Other Activities

Earth Observations            Rominger, Lopez-Alegria       
Bowersox
EVA (if needed)               Lopez-Alegria (EV1)           
Coleman (EV2)
IV Crewmember                 Thornton
Spacelab Activation           Thornton, Sacco
Spacelab Deactivation         Coleman, Leslie               
Lopez-Alegria

                        VEHICLE AND PAYLOAD WEIGHTS

Vehicle/Payload                                             
Pounds

Orbiter (Columbia) empty and 3 SSMEs                         
182,070

Spacelab and USML-2 Experiments                              
22,726

Middeck USML-2 Experiments                                   
897

Orbital Acceleration Research Experiment (OARE)              
249

DTOs/DSOs                                                    
129

Shuttle System at SRB Ignition                               
4,521,139

Orbiter Weight at Landing                                    
230,158

graphic

                      UNITED STATES MICROGRAVITY LABORATORY-
2
                                  (USML-2)

     The second United States Microgravity Laboratory (USML-
2) Spacelab mission builds on the foundation of its 
predecessor.

     The first USML mission, which flew aboard Columbia in 
1992 was one of the most successful NASA science missions.  
It provided new insights into theoretical models of fluid 
physics, the role of gravity in combustion and flame 
spreading, and how gravity affects the formation of 
semiconductor crystals.  Data collected from several protein 
crystals grown on USML-1 have enabled scientists to 
determine the molecular structures of those proteins.

     USML-1 was the first flight for four major experiment 
facilities -- the Drop Physics Module, the Surface Tension 
Driven Convection Experiment apparatus, the Crystal Growth 
Furnace and the Glovebox -- which promise to provide a 
valuable technology base for future flights.  A major 
objective of the USML program is to develop more capable 
instruments to support and refine mature space-based 
experimentation for the future. 

     Technical knowledge gained has been incorporated into 
the USML-2 mission plan to enhance procedures and 
operations.  Where possible, experiment teams have refined 
their hardware to increase scientific understanding of basic 
physical processes on Earth and in space, as well as to 
prepare for more advanced operations aboard the 
international Space Station and other future space programs.  

USML-2 Research

     Research during the mission is concentrated within the 
same overall areas as the first USML flight.  Reflown 
experiments will follow-up on results from that mission, 
probing for answers to the next level of scientific 
questions.

     Fluid physics research with the Drop Physics Module, 
the Surface Tension Driven Convection Experiment and the 
Gravitational Fluid Flow Cell will seek to improve 
understanding of fluid behavior and to apply that 
understanding to processes of scientific and technical 
importance.  Fluid physics is fundamental to many types of 
science, from the ways molten metals solidify and fuels 
burn, to the way planetary atmospheres operate.  In space, 
subtle and complex phenomena normally hidden by the stronger 
force of gravity can be revealed for detailed study.

     Materials science research in the Crystal Growth 
Furnace and the Zeolite Crystal Growth experiment will 
increase insight into the relationships between the 
structure, processing and properties of materials.  Mixtures 
that separate on Earth because of different component 
densities can be evenly mixed and processed in microgravity.  
This allows scientists to study the processing of such 
materials and to create advanced materials for study and 
comparison.  Without the pull of gravity and the associated 
convective flows, more perfect crystals can be produced, an 
advance many believe vital for creation of advanced computer 
chips and semiconductors.

     Biotechnology research on USML-2 will grow protein 
crystals in three different experiment facilities, 
attempting to produce crystals of sufficient size and 
perfection that scientists can determine their structure and 
how they form.  This approach is being pursued because of 
the promise it holds for the development of improved drugs.  
Two other biotechnology experiments address the development 
of food crops.

     Combustion science, a study of how the basic combustion 
process is affected by gravity, will be represented by one 
of seven technology investigations within the versatile 
Glovebox enclosure.  Understanding the way a fire starts and 
spreads without the interference of gravity could lead to 
more efficient fuels and improved fire safety, both in space 
and on Earth.

     Three sets of sensors will help scientists evaluate the 
quality of the microgravity environment, identifying factors 
which may disturb sensitive experiments.

     Several USML-2 experiments will look at how the 
presence or absence of gravity affects living organisms.  
This will aid long-term space efforts and also provide a 
better understanding of life on Earth.

     Commercial space processing technologies will again be 
demonstrated with the Commercial Generic Bioprocessing 
Apparatus, giving a large number of university and industry 
researchers access to space for their biological 
experiments.  Techniques for plant cultivation in 
microgravity will be further advanced in the Astroculture 
facility.  

     Several investigators will be able to view live video 
of their experiments at the same time, thanks to the new 
six-channel Hi-Pac video downlink system which will be 
making its first flight on USML-2.

The USML-2 Mission

     USML-2 experiment racks will be housed in a 23-foot 
Spacelab module inside the Shuttle Columbia's cargo bay.  
The laboratory module is pressurized so researchers can work 
in their shirtsleeves instead of bulky space suits, and it 
is furnished with much of the same kind of equipment that 
they would use in their labs back home.

     The seven-member crew will work in two 12-hour shifts, 
so experiment operations can continue around the clock.  The 
four payload crew members will conduct the majority of USML-
2 science operations.  NASA astronaut Dr. Kathryn Thornton 
is payload commander, and astronaut Dr. Catherine Coleman is 
a science mission specialist for the flight.  Dr. Fred 
Leslie of the Marshall Space Flight Center, Huntsville, AL, 
and Dr. Albert Sacco of the Worcester Polytechnic Institute, 
Worcester, MA, will serve as payload specialists on the 
USML-2 crew.

     USML-2 flight controllers and experiment scientists 
will direct science activities from NASA's Spacelab Mission 
Operations Control facility at the Marshall Space Flight 
Center.  In addition, science teams at several NASA centers 
and universities will monitor and support operations of a 
number of experiments.

graphic

Surface Tension Driven Convection Experiment 

     The Surface Tension Driven Convection Experiment 
apparatus allows investigators to view in great detail the 
basic fluid mechanics and heat transfer of thermocapillary 
flows, motions created within fluids by non-uniform heating 
of their free surfaces.  Temperature variations cause 
irregularities in the fluid's surface tension (the force 
which makes an unhindered liquid surface tend to form a 
sphere, like a raindrop), which in turn triggers flows in 
the fluid.  This thermocapillary flow, then, can also be 
referred to as surface-tension-driven convection.

     The facility uses a laser diode to illuminate particles 
suspended in silicone oil.  Particle motions due to fluid 
flows, created by heating the oil either internally or on 
its surface, are recorded by a video camera attached to a 
chamber viewport.  An infrared imaging system records oil 
surface temperature.  A third camera, in concert with an 
optical measurement system, is used to monitor oil surface 
deformations and motions.

     One key factor prompting this research is that unwanted 
fluid flows during melting and resolidifying can create 
defects in high-tech crystals, metals, alloys and ceramics.

     On Earth, natural convection creates the strongest 
flows:  colder, heavier fluid is pulled down, causing 
warmer, lighter fluid to rise.  Thermocapillary flows occur 
in many industrial and materials processing methods as well, 
and they are known to play an important role.  However, 
except in containers with very small dimensions like 
capillary tubes, thermocapillary flows are overshadowed by 
gravity-driven convection on Earth and are difficult to 
measure.

     In space, under microgravity conditions, 
thermocapillary flows become prominent and can be studied in 
detail.  Knowledge of their behavior and effects is 
important to a thorough understanding of fluid physics.  It 
is also necessary because these flows affect space 
applications such as bubble and droplet migration, fuel 
management and storage, and life support systems, as well as 
material processing methods like crystal growth from 
liquids, containerless processing, and welding.

     Understanding and controlling the effects of 
thermocapillary flows will become increasingly important as 
space flights become longer and space station operations 
begin.

Principal Investigator:
Dr. Simon Ostrach
Case Western Reserve University
Cleveland, OH

     This experiment will seek to measure the transition 
from steady, two-dimensional flows to oscillatory, or three-
dimensional, flows within silicone oil.  Thermocapillary 
flows sometimes show these periodic variations in fluid 
motion speed and temperature during the limited studies 
possible on Earth. 

     By comparing conditions for the onset of this 
oscillation in microgravity and on Earth, scientists will 
gain insight into what causes it.  Both steady 
thermocapillary flows and oscillatory flows may reduce the 
purity and uniformity of crystal growth solutions and molten 
metals.

     STDCE scientists will use this experiment to evaluate 
fluid flow models and theories of how thermocapillary flows 
transition from steady to oscillatory conditions.  They also 
will attempt to determine how and when oscillatory 
thermocapillary flows are created: how they are affected by 
different heat sources and shapes of free fluid surfaces; 
how flows affect surface shape; and what relationships exist 
among free surface deformation, surface temperature 
distribution, and fluid flow velocity.

     On USML-1, STDCE experimenters concentrated on steady-
state fluid flows, with results confirming many of their 
theoretical predictions.  However, no oscillations were 
observed.  On USML-2, three different sizes of experiment 
containers and several viscosities of oil will be used to 
create conditions favorable for oscillations.  The STDCE 
imaging system has been improved to make oscillations easier 
to observe.

Drop Physics Module

     The Drop Physics Module manipulates free-floating 
liquid drops in microgravity to test and expand current 
fluid physics models and theories and to measure the 
properties of liquid surfaces.

     People have been observing fluid phenomena for a long 
time.  One of the areas which fluid physicists are studying 
today is the interface, or boundary, between liquids, and 
its effects on the fluids on either side of it.  In space, 
where gravity's overwhelming influence is minimized, 
scientists can unmask and study more subtle forces that 
drive fluid behavior.  This fundamental knowledge can be 
beneficial for a variety of industries on Earth, from 
pharmacology to industrial chemistry. 

     The Drop Physics Module, operating in the microgravity 
environment of the Shuttle, allows investigators to study 
large drops in which dynamic phenomena will be slowed down 
and more easily seen.  They can observe how flows inside a 
drop and the drop's surface interact to provide a variety of 
dynamic events:  symmetric oscillations growing to become 
wild gyrations; dramatic splitting events where one drop 
breaks into two parts; and the centering of one drop within 
a second drop.  Equally important, studies of how small 
amounts of an additive can drastically alter the behavior of 
a liquid drop will be made.

     The module has a rectangular experiment chamber where 
liquid samples are deployed.  The samples are positioned by 
sound waves emitted by four loudspeaker drivers' one on 
each side of the chamber's bottom wall.  Gentle acoustic 
forces are all that are required to position the drops in 
the microgravity environment; this allows the liquid to 
assume its preferred shape, which is a perfect sphere.

     A crew member controls the sound waves in the chamber 
to make the spherical drops vibrate, rotate, split or 
recombine, while a camera records the drops' responses.  
Particles are mixed into the fluid samples before flight to 
make motion inside the drop visible.

     Experiment scientists will monitor drop behavior 
through real-time video, so they can assess their 
experiment's progress and can quickly suggest changes for 
the crew to make to improve the ultimate science return.  A 
film camera inside the module also can be used to make a 
high-speed record of the drops' behavior for later, more 
detailed analysis.

Drop Dynamics Experiment
Principal Investigator:
Dr. Taylor Wang
Vanderbilt University
Nashville, TN

     This experiment will gather high quality data on the 
dynamics of liquid drops in low gravity for comparison with 
theoretical predictions and ground-based studies using very 
small drops.  It will provide scientific and technical 
inputs for the development of new fields, such as 
containerless processing of materials and polymer 
encapsulation of living cells.

     On USML-1, Dr. Wang's team used the Drop Physics Module 
to confirm a theory that was more than 100 years old.  Using 
fluids ranging from water to oils, the module spun single 
drops until they formed a dog-bone shape.  All the drops 
changed into the same shape at the same point and at exactly 
the point that had been predicted over a century ago by 
fluid dynamics pioneer Lord Raleigh.

     Having resolved the issues surrounding the point at 
which the drops change shape, the team will use USML-2 to 
examine two new aspects of drop phenomena.  Again, results 
will help confirm or refine mathematical theories.

     One set of theories to be tested describes the 
fissioning, or breaking apart, of distorted drops as the 
viscosity (or thickness) of the fluid is varied.  Scientists 
will observe and analyze conditions at which various sizes 
and viscosities of drops split.

     The second thrust of this effort attempts to lay the 
ground work for encapsulating living cells which could be 
used to treat hormonal disorders: a spherical polymer shell 
would protect the cells from immunological attack and 
provide timed release.  The principal investigator will 
study the centering of shells (air bubbles within liquid 
drops) and compound drops (a drop of one liquid encased 
within a drop of a different liquid).  This investigation 
could demonstrate how to provide uniform encapsulation which 
would aid scientists in using polymer systems to encapsulate 
living cells.

     In the case of diabetes, an improved treatment would be 
to inject a pancreatic cell that secretes insulin into the 
body, rather than injecting insulin itself.  But the foreign 
cell would be immediately attacked by the patient's immune 
system.  If the cell were 

encapsulated in a spherical shell made of a material strong 
enough to withstand attack, yet porous enough to allow 
absorption of nutrients and excretion of insulin, it could 
enable a marked improvement in treatment for diabetes 
patients.

Science and Technology of Surface-Controlled Phenomena
Principal Investigator:
Dr. Robert Apfel
Yale University
New Haven, CT

     This study will use the Drop Physics Module to examine 
the influence of surfactants on the behavior of drops.  
Surfactants are substances which alter the surface 
properties of a liquid, aiding or inhibiting the way it 
adheres to or mixes with other substances.  Processes which 
rely heavily on surfactants are as varied as dishwashing 
(soap and water is the classic surfactant-liquid 
interaction), the manufacture of cosmetics, the dissolution 
of proteins in synthetic drugs, the recovery of oil and 
environmental cleanup.

     This investigation will have two parts.  The first set 
of experiments will explore single drop oscillation.  Drops 
with varying amounts of surfactants will be squeezed with 
sound waves; when the distortion is removed, the decay of 
the resulting oscillations can be analyzed.  The second set 
of experiments will investigate the coalescence or combining 
of drops with varying concentrations of surfactants.  
Surfactants should allow the drops to combine more easily, 
but this is not always the case.

     Both experiments will reveal surfactant behavior by 
creating novel situations that are not possible in Earth's 
normal gravity environment.  Moreover, information gained 
from the space experiments will enable ground-based 
scientists to accurately and conveniently measure materials 
properties during similar tests on Earth.

     Results of the surface-controlled phenomena 
investigation conducted during USML-1 were used to confirm 
and adjust theoretical models.  The USML-2 experiments will 
help further refine these theories.

Geophysical Fluid Flow Cell Experiment
Principal Investigator:
Dr. John Hart
University of Colorado
Boulder, CO

     The purpose of the Geophysical Fluid Flow Cell 
Experiment is to study how fluids move in microgravity, 
helping researchers understand the large-scale fluid 
dynamics of planetary and stellar atmospheres.

     The experiment cannot be done in ground-based labs 
because the downward pull of Earth's gravity there is unlike 
the acceleration in stars and planets.  In microgravity, 
different forms of acceleration can be simulated without 
interference.

     The experiment uses two hemispheres.  One, made of 
stainless steel and about the size of a baseball, is placed 
inside a transparent sapphire hemisphere, and a layer of 
silicone oil fills the space between the two.  They are 
mounted together on a turntable.  The transparent sapphire 
allows a clear view of the oil and conducts heat well so 
precise temperature control of the sapphire dome can be 
maintained.

     The temperatures of the inner and outer hemispheres are 
controlled by the experiment computer, as is the speed of 
rotation.  The heating creates a thermally driven motion in 
the oil, while the rotation mimics that present on rotating 
planets and stars.  A high-voltage electric field is applied 
across the silicone oil, creating a buoyancy force identical 
to buoyant forces on Earth and in other atmospheres being 
modeled.  The basic variables for the experiment are 
hemisphere rotation speed, voltage charge and temperatures.  
Once the variables are set and the experiment is running, 
thermally driven fluid flows within the rotating silicone 
oil are monitored.  Dr. Hart and his team will study 
variations in the fluid's thermal patterns for a wide range 
of external forces.  Different combinations of voltage, 
speed and temperature will be used during each run, creating 
unstable and turbulent flows in the rotating sphere shell 
that will help researchers better understand the dynamics of 
oceans, planetary atmospheres and stars.

     The Gravitational Fluid Flow Cell first flew on the 
Spacelab 3 mission (STS-51B) in 1985.  Several new types of 
convection were observed in the photographic data from the 
experiment, which contained images of convection structures, 
instabilities and turbulence, under varying conditions of 
different heating and rotation settings.  The USML-2 
experiment will expand on these results.  In addition it 
will investigate flow instability for  atmospheric flows 
that are more like the layers of Earth's atmosphere.  The 
science team also will investigate patter formations 
relevant to flows in the Earth's mantle, as well as 
temperature distributions not studied on Spacelab 3.

Crystal Growth Furnace

     The Crystal Growth Furnace is a reusable Spacelab 
facility for growing crystals of semiconducting material, 
metals and alloys.  The furnace, which had its debut on 
USML-1, is the first space furnace developed by the United 
States to process multiple large samples at very high 
temperatures (above 1,832 degrees Fahrenheit or 1,000 
degrees Celsius).  

     Atoms in many solids line up in orderly rows and 
columns, forming three-dimensional structures known as 
crystals.  By melting or vaporizing a material and then 
studying how it changes back from a liquid or gas into a 
crystalline solid, scientists can learn which conditions 
affect its physical, chemical and other properties.  They 
also can determine how these properties affect the 
material's performance.  Better understanding of these 
processes is desirable in designing or enhancing qualities 
in a specific material.

     Crystallization can be more effectively studied in 
microgravity than on Earth, because the gravity-induced 
phenomena that obscure or change the process are greatly 
reduced or eliminated.  Gravity-related complications such 
as convection, sedimentation and buoyancy can result in 
problems ranging from physical flaws in the internal 
structure of the crystal to uneven distribution of component 
materials within it.

     By analyzing space-grown crystals with well-defined, 
orderly atomic structures, investigators can increase their 
knowledge of many types of materials  both in space and on 
the ground.  In the future, this knowledge could result in 
improved materials, processing techniques, or products here 
on Earth.

     The four primary USML-2 Crystal Growth Experiments are 
continuations of investigations from USML-1.  Three will be 
grown with the directional solidification method, where a 
moving furnace allows the molten material to gradually cool 
from one end  to the other.  Since the crystal forms in only 
one direction, its atomic arrangement is more orderly and 
defect-free.

     The fourth experiment will grow crystals using the 
vapor crystal growth method.  The sample is heated until it 
begins to sublime, or turn from a solid into a gas.  The 
vaporized material diffuses into a cooler area of the 
apparatus where it is gradually deposited onto a base 
material and a single crystal forms.

     Near the end of the mission, a fifth sample will be 
processed in the furnace to determine the effect of 
different Shuttle attitudes on crystal growth.  
Solidification of a material whose behavior is well 
understood on Earth (germanium with a trace of gallium 
added), will begin with the Shuttle in the particular 
orientation thought to be best for crystal growth.  Midway 
through the crystal's processing, the Shuttle will maneuver 
to the standard "gravity gradient," or tail to Earth, 
attitude normally employed during microgravity missions.

Orbital Processing of High Quality Cadmium Zinc Telluride 
Compound Semiconductors
Principal Investigator:
Dr. David J. Larson Jr.
Northrop-Grumman Corp.
Research and Development Center
Bethpage, NY

     This experiment examines the effects of gravity on the 
growth and quality of alloyed compound semiconductors.  This 
experiment will attempt to produce high quality cadmium zinc 
telluride crystals with fewer physical defects and more 
uniform distribution of chemical components than those grown 
on Earth.

     Cadmium zinc telluride is used as a base, or substrate, 
on which infrared-detecting mercury cadmium telluride 
crystals are grown.  The alloying element, zinc, is added to 
minimize strain where the two crystals join, thereby 
reducing defects.  The resulting alloy, however, is a 
relatively soft material which can be deformed during the 
normal crystal growth process on Earth.  These deformations 
can introduce undesired changes in the arrangement of atoms 
in the crystal.

     By studying space-grown crystals, Dr. Larson can 
identify the effects of gravity as a factor in causing 
structural defects in the crystal system.  They should  be 
able to predict the distribution of chemical components 
within a crystal's important information for improving 
crystal growth technology on Earth.

     The cadmium zinc telluride crystal grown during USML-1 
was most defect-free where it completely touched the wall of 
the sample cylinder and where it did not touch the wall at 
all.  Therefore, the primary sample container on USML-2 will 
be outfitted with a spring-loaded piston, which will move to 
reduce the volume of the cylinder as the material contracts 
during cooling.  This should eliminate air voids in the 
crystal and ensure that it maintains even contact with the 
container wall along its entire surface.

The Study of Dopant Segregation Behavior During the Crystal 
Growth of Gallium Arsenide (GaAs) in Microgravity
Principal Investigator:
Professor D.H. Matthiesen
Case Western Reserve University
Cleveland, OH

     This experiment investigates techniques for uniformly 
distributing a small amount of selenium within a gallium 
arsenide crystal as it grows in microgravity.

     Electronic devices made from gallium arsenide crystals 
operate at higher speeds and use less power than computer 
chips and other semiconductor applications made from 
silicon.  Gallium arsenide is used in high-speed digital 
circuits, optoelectronic integrated circuits, solid-state 
lasers, and a variety of other products.

     Impurities such as selenium, called dopants, are added 
to these semiconductor compounds to improve or precisely 
control their electronic characteristics.  To produce high 
quality gallium arsenide crystals, scientists need to 
understand the process by which these impurities are 
distributed within the compound during crystal growth.

     Growing the crystals in microgravity will greatly 
reduce the gravitational influences that cause an uneven 
distribution of dopants in crystals grown on Earth.  This 
will allow Dr. Matthiesen to identify more subtle 
influences, either confirming or denying the theories and 
models used to control crystal growth on Earth.

     For the USML-2 experiment, the growing crystal will be 
marked every 100 to 300 seconds by electric pulsing.  The 
pulses will be time-coded to reveal the microscopic growth 
rate of the crystal and the shape and location of the 
liquid/solid boundary, or interface, at the various stages 
of growth.

Crystal Growth of Selected II-VI Semiconducting Alloys by 
Directional Solidification
Principal Investigator:
Dr. Sandor Lehoczky
NASA Marshall Space Flight Center
Huntsville, AL

     This experiment seeks to confirm theories about how 
gravity influences the introduction and distribution of 
structural defects in alloy semiconductors during crystal 
growth.  It will grow an approximately three-quarter-inch-
long crystal of mercury zinc telluride, which will be 
analyzed post-flight to determine its chemical and physical 
properties.

     Mercury zinc telluride is referred to as a II-VI alloy 
since its components appear in the vertical columns IIb and 
VIa of the periodic table of elements.  The crystals have 
properties that theoretically make them superior infrared 
detectors for use in defense, space, medicine and commercial 
industry.  The composition being grown on this mission has 
potential applications in instruments with diverse purposes 
ranging from locating and managing petroleum on Earth to 
studying distant stars and galaxies.

     By varying proportions of mercury, zinc and tellurium 
within the alloy, researchers can modify its electronic and 
optical properties to meet the needs of a range of 
applications.  However, the growth of large, single crystals 
of mercury zinc telluride containing a predetermined 
fraction of each chemical component is hampered by the 
complexity of the chemistry involved and by the effects of 
gravity during the growing process.  Experiments in 
microgravity should clarify the role that gravity plays in 
incorporating the different chemical components into the 
growing crystal.

Vapor Transport Crystal Growth of Mercury Cadmium Telluride 
in Microgravity
Principal Investigator:
Dr. Herbert Wiedemeier
Rensselaer Polytechnic Institute
Troy, NY

     The USML-2 version of this experiment focuses on the 
initial phase of vapor crystal growth in a complex alloy 
semiconductor.  Dr. Wiedemeier and his team will grow a 
crystalline layer of mercury cadmium telluride on a cadmium 
telluride substrate, or base, by the vapor crystal growth 
method.  The vapor transport method will cause layers, or 
thin films, of mercury cadmium telluride to be grown on the 
substrate in a process called epitaxial layer growth.  The 
resulting crystal will be analyzed to determine the effects 
of microgravity on the growth rate, chemical composition, 
structural characteristics and other properties of the 
initial crystalline layer that forms on the substrate.

     The similar crystal grown on USML-1 showed considerably 
improved quality over ground-based crystals.  During their 
follow-up analysis, investigators found new information 
about the effects of microgravity on formation of the 
initial layer deposited on the substrate.  Therefore, the 
USML-2 experiment zeros in on that stage of growth that 
determines the atomic arrangement of the entire crystal.

     The performance of infrared detectors made from this 
material will be greatly improved when electronics 
manufacturers can grow crystals without structural flaws and 
with more uniform distribution of chemical components.  
Better understanding of this crystal growth method will 
enhance ground based production of similar semiconductor 
materials and lead to further improvements in techniques for 
producing crystals using this process.

Zeolite Crystal Growth Furnace
Principal Investigator:
Dr. Albert Sacco
Worcester Polytechnic Institute
Worcester, MA

     On USML-2, Dr. Sacco will continue a series of 
experiments investigating the formation of zeolite crystals, 
widely used in the chemical process industry as filters, 
catalysts for reactions, and purifiers.  Using the Zeolite 
Crystal Growth (ZCG) furnace located on the Shuttle's 
middeck, scientists hope to gain a better understanding of 
the three-dimensional structure of these crystals, examining 
techniques for creating large, near-perfect zeolite crystals 
in microgravity and evaluating new mixtures of zeolite 
materials which will maximize growth and minimize defects.

     Zeolites can act as "molecular sieves" to separate out 
specific molecules from solutions.  They also are active 
catalysts converting one molecule to another.  Zeolites are 
used in life support systems, petroleum refining, waste 
management and biomedical fields for purification of fluids.  
High quality, near-perfect zeolites may one day allow 
gasoline, oil and other petroleum products to be refined 
less expensively.  Scientists, armed with a better 
understanding of how zeolites grow and of their crystalline 
structure, may be able to expand current uses of these 
crystals.

     Thirty-eight zeolite sample containers will be 
processed during the mission.  Each container will be loaded 
with two solutions' one aluminum-based and one silicon-
based.  A crew member will mix the solutions on orbit by 
turning a screw inside each separate sample container.  (The 
proper amount of mixing for different sample containers and 
mixtures will be dictated by results of Glovebox ZCG mixing 
tests early in the flight.)  The containers then will be 
placed in the ZCG furnace where they will be heated, 
allowing crystal growth to begin.

     ZCG flew for the first time on USML-1.  Results from 
that flight indicate that crystals whose nucleation and 
growth was controlled from the onset of the experiment 
achieved a higher degree of crystal perfection than any 
crystals produced on Earth.

Glovebox Facility
Project Scientist: 
Dr. Donald A. Reiss
NASA Marshall Space Flight Center
Huntsville, AL

     The Spacelab Glovebox, provided by the European Space 
Agency, is a versatile, transparent enclosure where 
experimenters can test and develop procedures and 
technologies in microgravity.  It enables crew members to 
handle, transfer, and otherwise manipulate materials in ways 
that are impractical in the open Spacelab.  The facility is 
equipped with photographic equipment that allows a visual 
record of experiment operations.

     The Glovebox cabinet provides a clean working space and 
minimizes contamination risks to both the Spacelab and 
experiment samples.  It provides two types of containment 
for small quantities of materials:  physical isolation and a 
lower air pressure inside the enclosure than that of the 
Spacelab module.  An air-filtering system also protects the 
crew from harmful experiment products.  When an airtight 
seal is required, crew members can insert their hands into 
rugged gloves attached to the glove doors.  If an experiment 
requires more sensitive handling, the crew may don surgical 
gloves and insert their arms through a set of adjustable 
sleeves.

     The Glovebox facility first flew on USML-1.  Its 
working area has been increased for this mission, and 
lighting has been improved.  On USML-2, the following seven 
investigations will use the facility. 

Interface Configuration Experiment
Principal Investigator:
Dr. Paul Concus
University of California , Berkeley
Berkeley, CA

     This follow-up to a USML-1 investigation studies the 
shapes that fluid surfaces assume within specific containers 
in microgravity.  It will observe how colored liquid settles 
to equilibrium within two different shapes of clear plastic 
containers.

     Currently, the behavior in microgravity of free liquid-
vapor interfaces, such as the way liquid propellant moves 
within spacecraft fuel tanks, cannot be predicted 
satisfactorily.  Since many on-orbit operations involve 
fluids and depend on their behaviors, it is important to 
test and refine the models used to predict how container 
shape can affect the location and shape of fluid surfaces.

Oscillatory Thermocapillary Flow Experiment 
Principal Investigator:
Dr. Yasuhiro Kamotani
Case Western Reserve University
Cleveland, OH

     This investigation, also a USML-1 follow-up, 
complements the Surface Tension Driven Convection 
Experiment.  It studies the conditions for the onset of 
oscillations, or periodic variations, in surface-
temperature-induced fluid flows.  Heat will be applied to 
silicone oil in four vessels of different volumes and depths 
to determine how container dimensions affect the onset of 
oscillations.

     On Earth, thermocapillary flows (those generated by 
temperature variations along a free liquid surface) begin to 
oscillate under certain conditions.  Both the flows 
themselves and the oscillations may reduce the purity and 
uniformity of crystal growth solutions and molten metals.  
By studying the conditions present when oscillations begin 
in microgravity and by comparing them to onset conditions 
present on Earth, scientists should be able to determine the 
cause of the oscillations.  

Fiber Supported Droplet Combustion 
Principal Investigator: 
Dr. Forman A. Williams
University of California, San Diego
San Diego, CA

     This new Glovebox investigation tests a technique for 
studying combustion in microgravity.  Droplets of different 
types of fuel will be suspended on a thin fiber, then 
ignited.  Team members will observe the shape of the flame, 
how the flame grows and how fast it shrinks as it consumes 
the fuel.

     Droplet combustion studies are very difficult to 
perform on Earth.  Drops burn unevenly because gravity 
causes high-density drops to sink and buoyancy-induced 
acceleration forces combustion products to rise.  In space, 
the drop is expected to assume a symmetrical sphere shape 
and thus burn more evenly, making it easier to validate 
combustion theories.  If successful, this new technique for 
studying droplet combustion could provide insight into 
fundamental combustion processes, such as how pollutants are 
formed.

Protein Crystal Growth,  Glovebox 
Principal Investigator:
Dr. Larry DeLucas
Center for Macromolecular Crystallography
Birmingham, AL

     This repeat of the highly successful USML-1 protein 
crystal growth Glovebox experiments will help confirm the 
advantages of crew interaction in the process of growing 
protein crystals in microgravity.

     Protein crystals, important for analyzing the molecular 
structure of these "building blocks of life," are very 
difficult to produce.  This experiment allows a crew member 
to modify protein crystal growth conditions such as mixing 
procedures, crystal seeding, crystal mounting and crystal 
preservation, based on his observations of previous sets of 
investigations.

     On USML-1, these modifications resulted in several 
crystals of much higher quality than had ever been grown 
before.  In addition to improving the quality of crystals 
grown on this mission, USML-2 Glovebox PCG research will be 
applied to improve protein crystal growth procedures on 
future Shuttle missions and on the Space Station.

Zeolite Crystal Growth,  Glovebox 
Principal Investigator:
Dr. Albert Sacco, Jr.
Worcester Polytechnic Institute
Worcester, MA

     This Glovebox investigation extends the USML-1 
evaluation of on-orbit mixing procedures for zeolite crystal 
growth experiments.  

     Zeolite crystals are used as catalysts and filters in 
the chemical processing industry.  To produce usable 
crystals, the growth solutions must be precisely mixed.  
USML-1 crew members' involvement in the mixing process 
resulted in more uniform mixing and helped minimize bubble 
formation.  The USML-2 experiment will provide additional 
mixing information to researchers using the Zeolite Crystal 
Growth Furnace facility.

Colloidal Disorder-Order Transitions 
Principal Investigator:
Dr. Paul Chaikin
Princeton University
Princeton, NJ

     This new Glovebox investigation looks at a fundamental 
question in condensed matter physics:  how the density of a 
substance finely and uniformly dispersed within another 
substance of a different phase a mixture called a colloid 
affects its transition from a liquid to an ordered solid 
phase.

     For this experiment, several containers will hold 
different concentrations of fine solid spheres suspended in 
a liquid.  Dr. Chaikin will observe which concentration of 
spheres is dense enough that they arrange themselves in an 
ordered state, rather than remaining randomly distributed 
within the liquid.

     A better understanding of what happens at the boundary 
between solid and liquid states of a colloid should help 
researchers improve materials processing methods on Earth, 
as well as in microgravity.

Particle Dispersion Experiment 
Principal Investigator:
Dr. John Marshall
NASA Ames Research Center
Moffett Field, CA

     This investigation, another follow-up from USML-1, uses 
the microgravity environment to study how fine natural 
particles, such as dust, disperse within an atmosphere, then 
assemble back together (or reaggregate) into larger 
clusters.  A short puff of air will disperse sand particles 
within a small, transparent container.  Dr. Marshall will 
observe how they cluster in an environment free from the 
interference of gravity.

     In addition to helping scientists understand how 
planetary atmospheres are cleansed of dust injected by 
volcanic eruptions, meteorite impacts or dust storms, the 
experiment tests technologies for future Shuttle and Space 
Station experiments concerned with the dispersion of 
aerosols.

     The USML-1 investigation successfully demonstrated the 
effectiveness of methods for dispersing, redispersing and 
studying the clustering of particles caused by electrical 
interparticle forces.  Electrical fields formed around some 
of the larger particle clusters.  If "giant" electrical 
fields actually occur in the natural environment, they could 
have a significant impact on the way dense dust clouds are 
dispersed.

Protein Crystal Growth Experiments

     A record number of protein crystal growth experiment 
facilities aboard USML-2 will be used to produce large, 
well-ordered crystals of various proteins under controlled 
conditions in microgravity.  The crystals will be used in 
ground-based studies to determine the molecular structure of 
each protein.

     Proteins play important roles in daily life, from 
providing nourishment to fighting disease.  Because a 
protein's structure determines its function, expanding 
knowledge of the structures of proteins has potential 
benefits to many areas of biotechnology the use of 
advanced techniques to improve the quality of biological 
products.  These benefits include new information on basic 
biological processes, development of food crops with higher 
protein content and increased resistance to disease, and 
basic research toward the development of more effective 
drugs.

     For many crystals, those grown in microgravity show a 
more uniform and highly ordered structure with fewer defects 
than are found in crystals of the same proteins produced on 
Earth.

     The protein crystal growth experiments on USML-1 were 
very successful.  Of the more than 30 protein crystals 
flown, nearly half produced crystals that were large enough 
for X-ray diffraction analysis.

     Canavalin, a plant protein, formed some of the largest 
crystals of that protein ever grown (more than 2.0 
millimeters long).  Crystals of Human Proline Isomerase, a 
protein associated with transplant rejection and a target of 
drug designers, yielded the highest quality data ever 
collected on the protein.

     Large, well-formed crystals of proteins important to 
immune disorder studies also were grown.  This included HIV 
Reverse Transcriptase Complex, a protein important in the 
design of drugs to fight AIDS.  The three-dimensional 
structure of Factor D, a protein that plays a role in 
complications including inflammation after open-heart 
surgery, was completed using the high-quality crystals 
obtained on USML-1.

     The variety of protein crystal growth experiment 
facilities on USML-2 reflects the progress made in this 
field over almost a decade of space experiments.  Growth 
methods and facility design are continually refined and 
upgraded, based on results from previous flights.

Single-Locker Protein Crystal Growth,  Two Methods
Principal Investigator: 
Dr. Daniel Carter
NASA Marshall Space Flight Center
Huntsville, AL

     This experiment will process more than 800 protein 
samples in a facility designed for the production of 
crystals with enhanced internal order.  The Protein 
Crystallization Apparatus for Microgravity (PCAM) holds more 
than six times as many samples as are normally accommodated 
in the same amount of space.

     The PCAM will grow crystals using the vapor diffusion 
method, which has been highly effective in previous Shuttle 
experiments.  In vapor diffusion, liquid evaporates from a 
protein solution and is absorbed by a reservoir solution 
contained in a wicking material.  As the protein 
concentration rises, the proteins form crystals.

     Twelve PCAM cylinders , each holding 63 samples for a 
total of 756, will be held in two temperature controlled 
enclosures, the Single-locker Thermal Enclosure System, each 
occupying a single Shuttle mid-deck locker.  The enclosures 
will maintain temperatures at 72 degrees Fahrenheit (22 
degrees Celsius).

     Eight Short PCAMs, containing precipitation ("salt") 
solutions, will be in an ambient-temperature stowage locker.  
They will be analyzed to determine the rate at which the 
vapor diffusion process proceeds in the diffusion-limited 
environment of microgravity.

     To start the PCAM experiments, a crew member will open 
the front of the enclosure, then rotate a shaft on the end 
of the cylinder with a ratchet from the Shuttle's tool kit.  
This will allow diffusion to start and protein crystal 
growth to begin.  Near the end of the mission, a crew member 
will rotate the shaft in the opposite direction to stop 
diffusion.

     A new experiment chamber called the Diffusion-
controlled Crystallization Apparatus for Microgravity (DCAM) 
also will be tested.  It will be housed within a Single 
Locker Thermal Enclosure System inside the Spacelab module.  
There will be 81 DCAMs containing protein samples in this 
enclosure.  The experiment will grow model proteins by a 
combination of the liquid-liquid diffusion and the dialysis 
methods of protein crystal growth.  This is a newly 
developed method by NASA scientists to passively control the 
crystallization process over extended periods of time.  The 
space-grown proteins will be compared with those grown by 
the same method on the ground.  The experiment is a 
precursor for long-duration crystallization experiments 
aboard the international Space Station and Mir, which would 
benefit greatly from the ability to control crystal growth 
times of up to approximately six months in length.

Crystal Growth by Liquid-Liquid Diffusion
Principal Investigator:
Dr. Alexander McPherson, Jr.
University of California, Riverside
Riverside, CA

     Four Handheld Diffusion Test Cell units containing four 
test cells each will grow protein crystals by diffusing one 
liquid into another.  In liquid-liquid diffusion, different 
fluids are brought into contact but not mixed.  Over time, 
the fluids will diffuse into each other through random 
motion of molecules.  The gradual increase in concentration 
of the precipitant within the protein solution causes the 
proteins to crystallize.  Liquid-liquid diffusion is 
difficult on Earth because differences in solution densities 
allow mixing by gravity-driven thermal convection.  In 
addition, the greater density of the crystals allows them to 
settle into inappropriate parts of the cell.

     The end of the test cells, where crystals will grow, 
and the containment housing are made of clear plastic.  Crew 
members will remove the units from stowage after launch and 
place them where they can photograph the growing crystals 
periodically during the mission.

     Each test cell has three chambers:  protein solution, 
buffer solution, and precipitant solution.  The buffer 
solution chamber cuts across the width of a shaft between 
protein and precipitant solutions.  Before the experiment, a 
valve is positioned so each fluid is isolated from the 
others.  A crew member will activate the experiment by 
rotating the valve 90 degrees, so the buffer contacts the 
protein and precipitant and the three form a single volume.  
The rotating valve minimizes liquid movement, limiting 
alteration of the liquids' shapes and  volumes.  When the 
three liquids are in contact, they will slowly diffuse into 
each other.  The crew will close the valves before return to 
Earth.

Commercial Protein Crystal Growth
Principal Investigator:
Dr. Larry DeLucas
Center for Macromolecular Crystallography
Birmingham, AL

     This experiment will grow large quantities of crystals 
of various proteins using the batch process method.

     A Protein Crystallization Facility will be housed in a 
commercial refrigeration/ incubation module in the Orbiter 
middeck.  The facility contains four cylindrical 
crystallization chambers which will be kept at 104 degrees 
Fahrenheit (40 degrees Celsius) until the Shuttle reaches 
orbit.  Then, they will be gradually cooled to 72 degrees 
Fahrenheit (22 degrees Celsius) over a 100-hour period.  The 
temperature change initiates crystal growth.  Crystals form 
as the chamber cools, and crystal growth continues at 72 
degrees for the remainder of the mission.

     The experiment also will grow additional crystals in a 
Vapor Diffusion Apparatus located in a 39-degree-Fahrenheit 
(4-degree-Celsius) refrigerator/ incubation module.  

Advanced Protein Crystallization Facility
Project Scientist:
Dr. Gottfried Wagner
University of Giessen
Giessen, Germany

     This facility is the first ever designed to use three 
methods of protein crystal growth:  liquid-liquid diffusion, 
in which a protein solution and a salt solution are 
separated by a buffer and allowed to mix together slowly 
once in orbit; dialysis, with protein and salt solutions 
separated by a membrane; and vapor diffusion, where crystals 
form inside a drop of protein solution as solvent from the 
drop diffuses into a reservoir.  Developed by the European 
Space Agency, the facility flew once before on the second 
International Microgravity Laboratory mission in June 1994.

     Video images will be made of crystals as they form.  
After the mission, the images will allow investigators to 
study the history of crystal development in microgravity.  
Scientists are interested particularly in why and how 
crystals nucleate and begin to form crystals.

Crystallization of Apocrystacyanin C
Principal Investigator:
Dr. Naomi Chayen
Imperial College
London, England

     This protein is a member of the lipocalin family of 
proteins, which binds to certain pigments that are widely 
distributed in plants and animals.  Knowledge of the 
structure of lipocalins will help scientists to alter these 
proteins to produce carriers that will bind more strongly to 
the pigment crocetin, which has anti-cancer properties.

Crystal Structure Analysis of the Bacteriophage Lamda 
Lysozyme
Principal Investigator:
Dr. Jean-Paul Declercq
Catholic University of Louvain
Belgium

     The bacteriophage Lambda lysozyme is a small protein of 
158 amino acids involved in the dissolution of the cell 
walls of bacteria.  Investigators are seeking information 
about the method of destruction employed by this organism.

Crystallization of RNA Molecules Under Microgravity 
Conditions
Principal Investigator:
Dr. Volker  Erdmann
Free University of Berlin
Germany

     Ribonucleic acid (RNA) molecules have diverse 
biological roles, which include carrying genetic information 
for protein synthesis within living cells.  They may also 
exhibit behavior characteristic of enzymes.  Because of the 
large mass of its molecules, RNA has been extremely 
difficult to synthesize on Earth.

Crystallization of the Protein Grb2 and Triclinic Lysozyme
Principal Investigator:
Dr. Arnaud Ducruix
Centre National De La Recherche Scientifique
Universite de Paris Sud, France

     Grb2 is an adapter protein involved in the transfer of 
signals from one cell to another.  Investigators expect that 
space-grown crystals will have better resolution than those 
which have been grown and analyzed in Earth-based labs.

     Lysozyme crystals grown in the APCF during the second 
International Microgravity Lab flight had a much higher 
level of perfection than those grown on earlier missions.  
USML-2 investigators want to extend the study to another 
crystalline structure of lysozyme, expecting to reach even 
better resolution values.

Microgravity Crystallization of Thermophilic Aspartyl-tRNA 
Synthetase and Thaumatin
Principal Investigator:
Dr. Richard Gieg
Centre National De La Recherche Scientifique
Strasbourg, France

     Investigators will continue and expand the IML-2 
crystallization studies on thermophilic aspartyl-tRNA 
synthetase and will crystallize the plant-sweetening 
protein, thaumatin.

     While both proteins are biochemically stable and are 
purified easily, they also have significant structural and 
behavioral differences.  Therefore, they make interesting 
subjects for comparative crystallography studies.

     In addition, thaumatin tastes extremely sweet when 
consumed by humans.  Since it appears to be non-toxic, non-
carcinogenic and low in calories, it may be a good sugar 
substitute.

Crystallization in Space of Octarellins, de novo Designed 
(alpha/beta)-Barrell Proteins, and of a Mutated Human TIM 
Forming a Monomeric (alpha/beta)-Barrell Structure
Principal Investigator:
Dr. Joseph Martial
University of Li ge
Belgium

     The long-term goal of investigators is to design a 
three-dimensional "scaffold" on which to build amino-acid 
bonds, eventually producing therapeutic agents for the 
treatment or prevention of disease.  Before this can be 
accomplished, more knowledge is needed about rules governing 
protein folding and structure stabilization.  Resolution of 
the three-dimensional structure of crystals of the synthetic 
protein octarellin may provide this information.

Crystallization in a Microgravity Environment of CcdB, a 
Protein Involved in the Control of Cell Death

Principal Investigator:
Dr. Lode Wyns
Free University of Brussels
Belgium

     Clarification of the structure and mode of action of 
this protein may lead to design of new antibiotics and anti-
tumoral drugs.  In this experiment, scientists want to 
improve crystal quality and produce crystals of two specific 
mutants, which have not produced crystals large enough for 
data collection on Earth.

A Multivariate Analysis of X-ray Diffraction Data Obtained 
from Glutathione S Transferase
Principal Investigator:
Dr. Lennart Sjlin
University of Gteborg
Sweden

     This experiment will perform extensive comparative 
analysis of X-ray data from space-grown crystals and ground-
based controls to provide a statistical comparison of the 
two.  This will give scientists statistically significant 
data to either confirm or refute various hypotheses about 
the value of a convection-free environment for enhanced 
crystal quality.

Protein Crystal Growth: Light-driven Charge Translocation 
Through Bacteriorhodopsin
Principal Investigator:
Dr. Gottfried Wagner
University of Geissen
Germany

     This protein converts light energy to voltages in the 
membrane of photoenergetic micro-organisms.  High quality 
bacteriorhodopsin crystals are difficult to grow on Earth 
because the crystalline clusters show structural disorder 
and loose bundling.  These crystals grown in the APCF during 
IML-2 had a much higher level of perfection, and for the 
first time in microgravity showed a precise tendency to form 
as cubes.  Resolution of the three-dimensional structure of 
bacteriorhodopsin will help scientists understand the 
mechanisms used to convert light energy to energy for 
growth.

Crystallization of Ribosomes
Principal Investigator:
Dr. Ada Yonath
Max-Planck Laboratory for Ribosomal Structure
Hamburg, Germany

     Ribosomes are responsible for the translation of 
genetic code to proteins.  While they are the only portion 
of living cells to have been crystallized, most Earth-grown 
crystals are very thin and crack on handling, making it very 
difficult to collect and evaluate data. 

     As APCF growth chambers are almost tailor-made for 
growing this type of protein, this experiment could result 
in crystals of improved internal order, shape, size and 
mechanical properties.  The facility also may allow 
scientists to control specific properties of the crystal's 
structure and form.

Crystallization of Sulfolobus Solfataricus Alcohol 
Dehydrogenase
Principal Investigator:
Dr. Adriana Zagari
University of Naples
Italy

     Alcohol dehydrogenase (ADH) is an enzyme that occurs in 
large amounts in the livers of mammals, where it plays an 
important role in several physiological functions including 
the breakdown of alcohol.  However, mammalian ADH is 
unstable at high temperatures or in the presence of organic 
solvents, properties that limit its usefulness for the 
synthesis of organic compounds.  On the other hand, ADH from 
the bacterium Sulfolobus solfataricus has greater thermal 
stability and is scarcely affected by the presence of 
organic solvents.  Given these properties, the enzyme is a 
good candidate for industrial applications.

Crystallization of Turnip Yellow Mosaic Virus, Tomato 
Aspermy Virus, Satellite Panicum Mosaic Virus, Canavalin, 
Beef Liver Catalase, Concanavalin B
Principal Investigator:
Dr. Alexander McPherson
University of California
Riverside, CA

     Canavalin, catalase and concanavalin B are being 
studied to determine the effects of microgravity on protein 
crystal growth by evaluating their size, habit, quality, 
defects and diffraction properties.

     Three viruses  very large proteins  are being studied 
to verify the theory that the effect of altered transport 
properties in microgravity should be magnified in proportion 
to the decreased diffusivity of such large molecules.

Crystallization of the Epidermal Growth Factor (EGF) 
Receptor
Principal Investigator:
Dr. Wolfgang Weber
University of Hamburg
Germany

     The receptor for epidermal growth factor is increasing 
in its importance as a predictor for a series of human 
malignancies.  Knowledge of its three-dimensional structure 
would open the possibility of tailoring drugs to treat 
numerous types of tumors.  At present, though, the crystal 
structure of only one hormone receptor (growth hormone) and 
none of the growth factor receptors has been solved.

Structure of the Membrane-Embedded Protein Complex 
Photosystem I
Principal Investigator:
Dr. Wolfram Snger
Free University of Berlin
Germany

     This protein complex is one of two responsible for the 
primary conversion of visible light into chemical energy in 
water-oxidizing photosynthesis.  This experiment aims to 
identify the complete arrangement of chlorophyll molecules 
that perform this conversion process in the most efficient 
way.

Crystallization of Visual Pigment Rhodopsin
Principal Investigator:
Dr. Willem de Grip
University of Nijmegen
The Netherlands

     Visual pigments like rhodopsin are the primary 
photoreceptor proteins for a variety of light-regulated 
processes, such as vision and photoperiodic reproduction.  
Analysis of the protein crystals is needed if scientists are 
to unravel the molecular mechanisms responsible for these 
processes.

Commercial Generic Bioprocessing Apparatus
Principal Investigator:
Dr. Louis Stodieck
Center for Bioserve Space Technologies
University of Colorado
Boulder, CO

     The Commercial Generic Bioprocessing Apparatus (CBGA) 
is a tool which allows a variety of sophisticated 
bioprocessing experiments to be performed in one piece of 
hardware.

     Many of the experiments which will be processed in the 
CGBA have applications that could improve life on Earth 
while providing solutions to issues related to extended 
stays in space.

     Each experiment is housed in a glass tube called a 
Fluid Processing Apparatus (FPA).  Groups of eight FPAs are 
packaged together so they can be activated simultaneously by 
turning a crank on the activation pack, and a number of 
activation packs are being flown on this mission.  Each FPA 
tube holds a neutral storage medium and the sample, an 
experiment activator that initiates bioprocessing, and a 
termination fluid that fixes the experiment for post mission 
analysis.  The fluids are separated by rubber stoppers.  
Once on orbit, a crew member mixes the samples and places 
them in an incubator for a preprogrammed period.  Processing 
is terminated automatically.  Samples will be removed and 
stored, some in the Spacelab module and others in middeck 
lockers, for the trip home.

     The CGBA flew for the first time on USML-1.  On that 
mission, biomedical experiments included investigations into 
how the human body fights disease, how infectious organisms 
like bacteria can be controlled, and how bacteria can be 

effectively used to treat waste and recover water  
information vital for long space flights.  There were 
experiments that investigated how cells and molecules 
develop and grow in reduced gravity, as well as seed 
germination experiments and experiments that looked at the 
microgravity effects on plant and animal development. 

     Major areas of investigation on USML-2 include: 

Biomedical Testing and Drug Development

     These experiments will help researchers develop a 
better understanding of how microgravity affects bone 
metabolism, the immune system and the neuromuscular system.

     Information gleaned from these experiments may help 
scientists understand the changes caused by exposure to 
microgravity in order to develop new drugs for the possible 
treatment of diseases such as cancer, osteoporosis and AIDS.

Ecological Test Systems

     This group of investigations will study plant 
development and the relationships between bacteria and 
plants in microgravity.  Such knowledge is crucial for 
extended stays in space where plants will be used as both a 
food source and a means of purifying air.

     The experiments will examine how controlled 
agricultural applications, waste management processes and 
methods of controlling microbes affect plant seeding, seed 
germination, plant development and bacterial products and 
processes of plants.

Biomaterials Products and Processes

     These experiments will study the growth of bacteria in 
microgravity, investigate new pharmaceutical products and 
delivery systems, and study materials that might be used as 
replacements for skin, tendons, blood vessels and corneas. 

     Scientists hope to glean important information on how 
bacteria grow in the absence of gravity-driven fluid flows, 
as well as gaining insight on how to grow structures that 
can deliver drugs directly to cells.  These investigations 
also will provide important information on models for 
potential implants, such as synthetic skin for burn victims.

Astroculture Facility and Experiment
Principal Investigator:
Dr. Raymond J. Bula
Wisconsin Center for Space Automation & Robotics
Madison, WI

     The Astroculture facility is an apparatus used for 
growing plants in microgravity.  There are two USML-2 
objectives for Astroculture.  1) The facilitys three main 
subsystems will be tested to verify the apparatus as an 
effective on-orbit plant growth system, and 2) the facility 
will be used to investigate the nature of starch 
accumulation in microgravity.

     Because plants will play an important role in future 
long-duration space flights, providing crews with oxygen, 
food, pure water and assisting in removing carbon dioxide 
from space habitats, it is important to develop an effective 
plant growth facility.  USML-2 will evaluate the facility's 
plant watering and nutrient-delivery system, humidity 
control and plant illumination subsystems.

     The plant watering system must be able to deliver 
nutrients to the plants without releasing solutions into 
crew quarters.  The Astroculture facility on USML-2 will 
test the effectiveness of a delivery system using porous 
tubes with different pressures to ensure a proper flow to 
the plants' roots.

     Another requirement of the facility is successful 
humidity control.  Air moisture must remain at levels that 
do not damage experiments and equipment, while maintaining 
desired humidity levels to plants.  The moisture in the air 
also may be recycled as condensed water for cooking, 
drinking or as a source of water for plants.  On USML-2 the 
system will humidify and dehumidify the air without needing 
a gas/liquid separator to recover the condensed water.  All 
current systems in use must supply a separator.

     The third requirement for a reliable plant growth 
system is efficient use of lighting, since electrical power 
is at a premium on Shuttle flights.  The lighting subsystem 
tested on USML-2 uses light emitting diodes (LEDs) providing 
high levels of light within the limits of electrical power 
available on orbit.  Its energy conversion capability makes 
it superior even to fluorescent or sodium lamps.  It also 
provides greater safety than any other light sources 
currently used by space-based plant growth facilities.

     During USML-2, small potatoes will be grown from potato 
leaf cuttings that can be induced to develop small tubers 
filled with starch in 10 to 15 days.  Starch is an important 
energy storage compound in plants, and there are indications 
that starch accumulation in plants is restricted in 
microgravity.  The crew will periodically monitor the status 
of the environment in the Astroculture plant chamber and the 
development of the potato plants.  Video of the plants will 
be downlinked periodically during the mission.  Post-mission 
evaluation of data will focus on rates of photosynthesis, 
movement of photosynthesis products from leaves to tubers, 
conversion of sugars to starch in storage organs, and enzyme 
activities for the formation and degradation of starch.  
Investigators also will study the number, size, shape and 
distribution of starch grains and the structures that form 
starch.

     The Astroculture equipment has previously flown on the 
USML-1, and SPACEHAB 1, 2 and 3 missions.  During these 
flights lighting, humidity, acidity-alkalinity balance (pH), 
nutrient supply and composition, and carbon dioxide and 
atmospheric contaminant subsystems were successfully 
evaluated.  Technology progress from previous flights has 
resulted in several commercial products for use on Earth.  
The lighting subsystem has provided technology to develop a 
unique lighting system for photosynthesis research and for 
use in some medical applications.  Other commercial products 
from Astroculture technology include 
dehumidification/humidification units, water-efficient 
irrigation systems and energy-efficient lighting systems for 
large scale commercial nurseries.

     After flight qualification on USML-2, the plant growth 
facility will be available for sale or lease to commercial 
enterprises.  The project is part of a cooperative 
experiment with the Secondary Payload Programs of NASA's 
Office of Life and Microgravity Sciences and Applications.

Measuring Microgravity

     Whether on Earth or in space, any change in motion 
produces accelerations, or gravity.  An astronaut exercising 
on the Space Shuttle, for instance, can cause the Orbiter to 
vibrate in response to the activity taking place inside it, 
creating gravity.  Experiments on the Shuttle need a very 
stable microgravity environment so their delicate operations 
will not be disturbed.  But with essential activities such 
as astronauts living and working on the Shuttle, Orbiter 
maneuvers, and antenna motions, absolute stability is 
impossible to achieve.  Therefore, to interpret results 
correctly and to develop an understanding of the effects 
caused by these forces, investigators need to know the 
precise strength of gravitational influences and vibrations 
affecting their experiments.  USML-2 will include three 
facilities to measure different types of accelerations, and 
it will test a device that could be used to isolate 
sensitive experiments from disturbances.  

Space Acceleration Measurement System
Project Manager:
Ron Sicker
NASA Lewis Research Center
Cleveland, OH

     The Space Acceleration Measurement System is a facility 
that measures the acceleration environment of the Spacelab 
module using three sensor heads to record accelerations over 
a specific range of frequencies.  Sensors located on the 
Surface Tension Driven Convection Experiment, the Crystal 
Growth Furnace and the Glovebox will be connected by cables 
to a control and data storage unit in the Spacelab center 
aisle.

     Data from SAMS will be used to determine what effect 
crew movements, equipment operations and Shuttle maneuvers 
can have on the experiments being conducted on USML-2.  
Scientists will analyze the data post-flight to determine 
that a disturbance took place at a particular time.  They 
can then make allowances for the disturbance as they analyze 
their experiment data.  

Three Dimensional Microgravity Accelerometer
Principal Investigator:
Jan Bijvoet
University of Alabama, Huntsville
Huntsville, AL

     The Three Dimensional Microgravity Accelerometer (3DMA) 
apparatus will take two kinds of measurements on USML-2:  
the absolute level of microgravity acceleration, (the 
differences between zero acceleration and what is 
experienced during the mission), and microvibrations which 
could affect the investigations onboard.  Using these two 
measurements, scientists can know the acceleration effects 
any time during their experiments.

     Located in the central housing of the 3DMA hardware are 
three accelerometers which measure the level of absolute 
microgravity in three separate axes or directions.  Three 
remote sensors will record the different vibrations and 
accelerations caused by experiment and Orbiter operations. 

     The data will be recorded in the central 3DMA unit for 
post-mission analysis.  It will also be sent to the ground 
in real time.  This will allow scientists to call up 
displays to view measurements of absolute gravity and 
microvibrations at the same time.  The absolute level of 
microgravity and the data from the three remote sensors will 
allow quantification of disturbances.

Orbital Acceleration Research Experiment
Porject Manager:
Jose L. Christian, Jr.
NASA Lewis Research Center
Cleveland, OH

     The Orbital Acceleration Research Experiment (OARE) is 
managed by Lewis Research Center as part of NASA's 
Microgravity Measurements and Analysis Project.  Located 
outside the Spacelab, the OARE acceleration instrument will 
measure microgravity levels caused by atmospheric drag of 
the Shuttle, changes in Orbiter velocity and vibrations of 
onboard machinery, as well as Shuttle and crew operations.

     Data from OARE will complement information gathered 
from the SAMS instrument.  While SAMS data on Shuttle 
accelerations will be analyzed post-mission, high-resolution 
data from the sensitive OARE instrument will be sent real-
time to the ground.  This will give scientists an 
opportunity to make on-the-spot adjustments to their 
experiments to account for the on-orbit disturbances.  

Suppression of Transient Accelerations By Levitation 
Evaluation 
Project Scientist:
Dr. Gerald Nurre
Marshall Space Flight Center
Huntsville, AL

     The Suppression of Transient Accelerations By 
Levitation Evaluation (STABLE) will test a device designed 
to isolate a small science experiment from high-frequency 
accelerations, including Shuttle operations and crew 
activity.

     The entire device fits into a single locker space in a 
Spacelab rack, the bottom of the locker serving as the base 
of the isolator.  The platform is suspended from the base in 
the center of the locker by three electromagnetic actuators, 
mechanisms which move and control the platform.  Each 
actuator is composed of a magnet, permanently attached to 
the platform, and a coil assembly, bolted to the base.  
Accelerometers are mounted both on the platform and the 
base, providing feedback of acceleration measurements 
through a feedback controller, also contained in the locker.  
This feedback allows position sensors to locate the platform 
with respect to the base and are used to maintain the 
platform near its centered position, thus producing a 
microgravity environment on the platform.  

High-Packed Digital Television Technical Demonstration

     This is the first flight demonstration of a new digital 
television system to operate from the Spacelab.  It will 
provide researchers on the ground with up to six channels of 
video which can be transmitted simultaneously from orbit.  
Previously, only one video channel at a time could be sent 
down, or downlinked, limiting the accessibility of video 
data from experiments and other activities.  Experiments 
requiring live video for analysis by ground teams had to be 
scheduled at different times.

     The new six-channel system will increase science return 
from the USML-2 mission, since a number of science teams 
will be able to monitor and modify operation of their 
experiments simultaneously.  The HI-PAC TV technology will 
serve the remaining Spacelab missions and will extend well 
into the Space Station era.

     Using the Spacelab's high-rate data system, HI-PAC 
converts standard analog video signals into digital signals, 
compressing the signal and downlinking it the same way as 
other digital data.  When the signals are received on the 
ground, the digital data will be converted back into analog 
signals, then distributed to scientists for viewing on 
monitors in the science operations area.

STUDENTS PARTICIPATE IN MISSION INVESTIGATIONS

     During STS-73, students at four sites will interact 
with the astronauts to discuss and compare onboard 
microgravity experiments with similar, ground-based 
experiments.  The goal is to involve students as 
participants in Shuttle investigations in an effort to 
generate excitement in physical science and chemistry.

     The first live downlink with students is currently 
scheduled for flight 
day 12.  Middle school students at the following sites will 
discuss mixing and 
crystal growth experiments with the Shuttle crew. 

     1. Museum of the Rockies, Bozeman, MT.  Mixing and 
sedimentation.

     2.  Sierra Middle School, Las Cruces, NM.  
Crystallization experiments.

     The second live downlink is scheduled for flight day 
13.  High school 
students from the following sites will discuss fluids and 
combustion 
experiments:

     1.  South High School, Worcester, MA.  Fluid 
experiments.

     2.  Louisville Science Center, Louisville, KY.  
Combustion experiments.

     Prior to the mission, NASA's education specialists 
visited the sites to 
work with students on their experiments.  

     A pre-flight education video of the STS-73 crew 
conducting the ground-based experiments and an accompanying 
"Microgravity Teacher's Guide with Activities for Physical 
Science" are available through the NASA Teacher Resource 
Center network. 

     Teachers can access copies of the ground-based 
activities through the "Hot Topics" section in SPACELINK, 
NASA's electronic network for educators.  These experiments 
use affordable and easily acquired materials.  For this and 
other information, SPACELINK can be accessed via modem line 
(205) 895-0028; WWW address http://spacelink.msfc.nasa.gov; 
and Telnet, Gopher and Anonymous FTP address 
spacelink.msfc.nasa.gov.

STS-73 CREW BIOGRAPHIES

     Navy Commander Kenneth D. Bowersox, 38, will lead the 
seven-member STS-73 crew during its 16-day mission in space.

     Bowersox was born in Portsmouth, VA, but considers 
Bedford, IN, to be his hometown. He received a bachelor's 
degree in aerospace engineering from the United States Naval 
Academy in 1978, and a master's degree in mechanical 
engineering from Columbia University in 1979.

     Bowersox received his commission in the Navy in 1978 
and was designated a Naval Aviator in 1981.  He was then 
assigned to Attack Squadron 22 aboard the USS Enterprise.  
Following graduation from the United States Air Force Test 
Pilot School at Edwards Air Force Base, CA, in 1985, he 
moved to the Naval Weapon Center at China Lake, CA.

     Bowersox was selected as an astronaut candidate in June 
1987.  Since then he has held a variety of technical 
assignments including flight software testing in the Shuttle 
Avionics Integration Laboratory; technical assistant to the 
director of flight crew operations; chief of the Astronaut 
Office Safety Branch; and spacecraft communicator in the 
Mission Control Center.  A veteran of two space flights, 
Bowersox has logged more than 591 hours in space.

     His first flight, STS-50 in June/July 1992, was the 
first flight of the U.S. Microgravity Laboratory.  Over a 
two-week period, crew members conducted a variety of 
experiments in materials processing and fluid dynamics in 
weightlessness.  At that time, STS-50 was the longest 
Shuttle flight to date.  Bowersox's second flight was as 
pilot of STS-61 in December 1993 which featured the 
servicing of the Hubble Space Telescope.  During the 11-day 
mission, crew members conducted a record five spacewalks to 
restore the telescope to its full operating capacity.

     Colorado native and Navy Commander Kent Rominger, 39, 
will be making his first Shuttle flight on STS-73.

     Born in Del Norte, CO, Rominger received a bachelor's 
degree in civil engineering from Colorado State University 
in 1978 and a master's degree in aeronautical engineering 
from the U.S. Naval Postgraduate School in 1987.  Rominger 
received his commission through the Aviation Reserve Officer 
Candidate Program in 1979 and was designated a Naval Aviator 
in September 1980.  Following training in the F-14 Tomcat, 
he was assigned to Fighter Squadron Two and attended the 
Navy Fighter Weapons School.  In 1987, he completed Naval 
Postgraduate School/Test Pilot School Cooperative Program, 
and was assigned as the F-14 Project Officer to the Carrier 
Suitability Branch of the Strike Aircraft Test Directorate 
at Patuxent River, MD.  During his tour of duty, he 
completed initial carrier suitability sea trials of the F-
14B, logging the first aircraft carrier assessment and 
catapult launch in the upgraded Tomcat.  In 1990, he 
reported to Fighter Squadron 211 where he served as 
Operations Officer and completed a Desert Storm Deployment 
of the Arabian Gulf aboard the USS Nimitz.

     Rominger was selected as an astronaut candidate in 
1992.  He has since completed his candidate training and has 
been working technical issues for the Astronaut Office 
Operations Development Branch.

     Three-time Shuttle veteran Kathryn Thornton, Ph.D., 43, 
will serve as Payload Commander and Mission Specialist 3 for 
the USML-2 mission.  A native of Montgomery, AL, Thornton 
received a bachelor's degree in physics from Auburn 
University in 1974 as well as a master's degree and 
doctorate in physics from the University of Virginia in 1977 
and 1979, respectively.

     After receiving her doctorate degree, Thornton was 
awarded a NATO Postdoctoral Fellowship to continue her 
research at the Max Planck Institute for Nuclear Physics in 
Heidelberg, West Germany.  She then returned to 
Charlottesville, VA, where she was employed as a physicist 
at the US Army Foreign Science and Technology Center.

     Thornton completed her initial training as a NASA 
astronaut in 1985, and since then has logged more than 593 
hours in space, including more than 21 hours of 
extravehicular activity.

     Her first flight, in November 1989, was a five-day 
mission sponsored by the Department of Defense.  Her second 
flight in May 1992 was aboard the maiden voyage of the Space 
Shuttle Endeavour on a mission to retrieve, repair and 
redeploy the International Telecommunications Satellite 
(INTELSAT), and to demonstrate and evaluate numerous EVA 
tasks to be used for the assembly of a space station.  
During that mission, Thornton and fellow crew member Tom 
Akers conducted a seven hour, 45 minute spacewalk.

     On her third flight, Thornton was part of the team that 
conducted five spacewalks to service and repair the Hubble 
Space Telescope.  During the December 1993 mission which 
lasted 11 days, Thornton performed two of the spacewalks, 
spending more than 13 EVA hours.

     Air Force Captain Catherine Coleman, Ph.D., 34, will be 
making her first space flight as Mission Specialist 1 during 
STS-73.

     Born in Charleston, SC, Coleman received a bachelor's 
degree in chemistry from the Massachusetts Institute of 
Technology in 1983, and a doctorate in polymer science and 
engineering from the University of Massachusetts in 1991.

     Coleman was commissioned as a 2nd lieutenant in the Air 
Force in 1983 and began graduate work at the University of 
Massachusetts.  In 1988, she entered active duty and was 
assigned to Wright-Patterson Air Force Base as a research 
chemist.  She did research on new polymer materials and 
acted as a surface analysis consultant for the Long Duration 
Exposure Facility.  In addition to assigned duties, Coleman 
was a volunteer test subject for the centrifuge program at 
the Crew Systems Directorate of the Armstrong Aeromedical 
Laboratory.  She set several endurance and tolerance records 
during her participation in physiological and new equipment 
studies.

     Coleman was selected as an astronaut in 1992.  Her 
technical assignments have since included working in the 
Astronaut Office Mission Support Branch and for flight 
software verification in the Shuttle Avionics Integration 
Laboratory.

     Also making his first flight as Mission Specialist 2 is 
Navy Lieutenant Commander Michael Lopez-Alegria.

     Lopez-Alegria, 37, was born in Madrid, Spain, and 
considers both Madrid and Mission Viejo, CA, to be his 
hometowns.  He earned a bachelor's degree in systems 
engineering from the U.S. Naval Academy in 1980, and a 
master's degree in aeronautical engineering from the U.S. 
Naval Postgraduate School in 1988.

     Lopez -Alegria was designated a naval aviator in 1981.  
He then served as a flight instructor in Pensacola, FL, 
until March 1983.  His next assignment was to a fleet 
electronic reconnaissance squadron in Rota, Spain, where he 
served as a pilot and mission commander aboard EP-3E 
aircraft, flying missions in the Mediterranean Sea, North 
Atlantic, Baltic Sea and Central America.  In 1986, he was 
assigned to a two-year cooperative program between the Naval 
Postgraduate School in Monterey, CA, and the U.S. Naval Test 
Pilot School in Patuxent River, MD.  His final tour before 
being assigned to NASA was at the Naval Air Test Center as 
an engineering test pilot and program manager.

     Lopez-Alegria also was selected as an astronaut in 
1992, and has worked with the Space Shuttle Orbiter, Main 
Engine, Solid Rocket Booster and External Tank projects.

     The crew roster for STS-73 also includes two Payload 
Specialists -- Fred Leslie, Ph.D., from the Marshall Space 
Flight Center, and Albert Sacco, Jr., Ph.D., from Worcester 
Polytechnic Institute.

     Leslie, 43, was born in Ancon, Panama.  He received a 
bachelor's degree in engineering science from the University 
of Texas in 1974, and a master's and doctorate degrees in 
meteorology with a minor in fluid mechanics from the 
University of Oklahoma in 1977 and 1979, respectively.

     After earning his doctorate, Leslie served as a post 
doctoral research associate at Purdue University studying 
fluid vortex dynamics.  In 1980, he worked for the 
Universities Space Research Association as a visiting 
scientist at the Marshall Space Flight Center.

     Since 1983, Leslie has served as a co-investigator for 
the Geophysical Fluid Flow Cell experiment which flew on the 
Spacelab 3 mission and is part of the USML-2 payload.  He 
also was a principal investigator for the Fluid Interface 
and Bubble Experiment examining the behavior of a rotating 
free surface aboard NASA's KC-135 aircraft.  He is the 
author of 27 journal papers, 45 conference papers, and nine 
NASA reports involving atmospheric and fluid dynamic 
phenomena.

     In 1987, he became chief of the Fluid Dynamics Branch 
where he directed and conducted research in both laboratory 
and theoretical investigations.  He was also the mission 
scientist for the Japanese Spacelab mission, STS-47.  STS-73 
will be his first space flight.

     A native of Boston, MA, Sacco, 46, received a 
bachelor's degree with honors from Northeastern University 
in 1973 and a doctorate from the Massachusetts Institute of 
Technology in 1977, both in chemical engineering.  Since 
1977, Sacco has been on the faculty at Worcester Polytechnic 
Institute in the Department of Chemical Engineering, 
splitting his time between research and teaching.  He was 
appointed department head in 1989.  He has consulted for 
numerous companies in the field of catalysis, solid/gas 
contacting, and equipment design for space applications.  
Also, with his father and brother, he ran a family 
restaurant in Boston for more than 20 years.

     Sacco has over 70 publications in the areas of carbon 
filament initiation and growth, catalyst deactivation, and 
zeolite synthesis.  He is the principal investigator for the 
Zeolite Crystal Growth Experiment and served as an alternate 
payload specialist on USML-1.

     The alternate payload specialists for the USML-2 
mission are Glynn Holt, a research scientist at NASA's Jet 
Propulsion Laboratory, and David Matthiesen, an assistant 
professor of Materials Science and Engineering at Case 
Western Reserve University.

     Holt, 35, a native of Plainview, TX, has performed 
significant research in support of the Drop Physics Module 
Program.  He has authored numerous papers on drop behavior 
and gas bubble phenomena in both 1-G and microgravity 
environments.  He is a co-investigator for the Drop Physics 
Module for both USML-1 and USML-2.

     Matthiesen, 37, a native of Blue Island, IL, has 
conducted extensive material processing research both in the 
laboratory and in low gravity aboard the KC-136.  He was 
principal investigator on the USML-1 gallium arsenide 
experiment and will serve as PI for a similar activity on 
USML-2.

UPCOMING SHUTTLE MISSIONS (graphic)

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