ISS Science Operations Status Report for week ending 09-11-02

Flight Engineer Peggy Whitson completed the final three
sample runs of a semiconductor materials experiment during the past week aboard
the International Space Station.

Whitson installed and activated the sixth sample Sept.
4 in the Solidification Using a Baffle in Sealed Ampoules (SUBSA) experiment.†
On Saturday, she installed and started the seventh sample run of the Expedition
and removed it Sunday after completing a normal 15-hour heating and cool-down
cycle.† On Tuesday, Whitson installed and initiated the eighth and final sample
run of Expedition Five.†† She is scheduled to remove the sample today.† The
experiment was conducted in the Microgravity Science Glovebox facility
in the Destiny laboratory module.†

SUBSA examines the solidification of semiconductor
crystals from a melted material.† For this investigation, tellurium and zinc
— known as dopants — are added to molten indium antimonide specimens that are
then cooled to form a single solid crystal.† Uniform distribution of the tellurium
and zinc are important in controlling the opto-electronic properties of the
semiconductors.† In the low gravity environment of the Station convection-driven
fluid motion in the molten material is substantially reduced, giving scientists
a better look at residual non-convective fluid transport during semiconductor
material formation. The goal of SUBSA is to identify what causes the non-convective
motion in melted materials processed in space and to reduce the magnitude of
the motion so that more homogenous distribution of the dopants is achieved in
the solidified crystal.

ìI would say our first Glovebox experiment has been
very successful,î said SUBSA Project Scientist Dr. Martin Volz, of NASAís Marshall
Space Flight Center in Huntsville, Al. “Itís safe to say it’s the first time
in space that anybody has actually seen the processing of a semiconductor.
Earlier space experiments were done in metal cartridges, while ours were done
in clear quartz sample tubes, while we watched on video from the ground. It
helped us figure out how hot we needed to get the furnace to melt just the right
amount of semiconductor seed material. Without it, we would have had to rely
on sensors that were not as accurate. The video has enabled us to see the real
growth rate of the sample, whether it’s constant and whether microgravity affects
the growth rate.”

The samples will be stored onboard for return on a
future Space Shuttle mission, Volz said. Some initial x-ray analysis will be
conducted at NASA’s Kennedy Space Center, a short distance from the Shuttle
landing strip before the samples are returned to Principle Investigator Dr.
Aleksandar Ostrogorsky, of Rensselaer Polytechnic Institute, Troy, N.Y., for
more detailed study.

Volz added that the Glovebox also proved itself in
supporting Station research.

“These kinds of experiments that involve potential
hazards to the crew or the Station wouldn’t have been possible without the high
level of containment and safety provided by the Microgravity Science Glovebox,”
he said.

Also today (Wednesday), Whitson will begin onboard
familiarization and setup for the Pore Formation and Mobility Investigation
(PFMI) in the Glovebox. She will install the new experiment today.. After
reconfiguring the Glovebox for the new experiment and conducting a series of
checkout tests, including a non-sample test run commanded from the ground, the
crew is expected to begin the first PFMI tests on Sept. 17 and

Sept. 19. PFMI also uses a furnace to process materials. It will melt and
resolidify samples of a transparent modeling material, succinonitrile and succonontrile
water mixtures, to observe how bubbles form in the samples and study their movement.
Bubbles that become trapped in metals or crystals can form defects that decrease
the material’s strength and usefulness. Scientists hope to gain insights that
will improve solidification processing in a microgravity environment and similar
processes on Earth.

On Saturday, the crew took documentation photos of the Advanced Astroculture
experiment. This commercial experiment is growing soybean plants during Expedition
Five to determine if the space-grown plants produce seeds with unique chemical
composition that could be beneficial to agriculture.

On Monday, the crew conducted the regular monthly session with the Pulmonary
Function in Flight (PuFF) experiment. This ongoing research focuses on
lung function both inside the station and following spacewalks.

On Thursday, the crew is scheduled to conduct a 21-day
pre-spacewalk background radiation check with the EVA Radiation Monitoring
(EVARM) experiment, which records radiation levels received by specific
parts of the human body inside the Space Station and during spacewalks outside
the Station.

On Friday, selected members of the crew are scheduled
to participate in the Crew Interactions experiment. Based on the results
of the weekly surveys of both Station crews and ground teams, the study will
examine issues involving tension, cohesion and leadership roles in the crew
in orbit and in the ground support crews.

Photography subjects for the Crew Earth Observations
project this week included: Perth, Australia, landslides in the Cornish moors
of the United Kingdom, Damascus, Syria, Saharan dust along the Libiyan and Tunisian
coastlines, Barcelona, Space, Puerto Rico, St. Coix, the lower Amazon River
basin, the Pilcomayo swamplands in Paraguay and Argentina, and Necker Island
in the Hawaiian chain.

Automated experiments involving biological materials,
space construction materials, the station’s vibration environment, and plant
growth continued to function well aboard the Station, while liver cell, petroleum
processing and drug delivery experiments have been completed and are stored
for return to scientists on Earth. The crew continued its daily payload status
checks to make sure that all experiments and payload facilities continue to
operate properly.

Editor’s Note: The Payload Operations Center at NASA’s Marshall
Space Flight Center in Huntsville, Ala., manages all science research experiment
operations aboard the International Space Station. The center is also
home for coordination of the mission-planning work of a variety of international
sources, all science payload deliveries and retrieval, and payload training
and payload safety programs for the Station crew and all ground personnel.