STS-94 Day 14 Highlights
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- On Monday, July 14, 1997, 6:00 a.m. CDT, STS-94 MCC Status Report # 26
- On-orbit science investigation continues to be the focus of
Columbia's Microgravity Science Laboratory mission as the seven
astronauts work around the clock on two shifts supporting the more
than 30 experiments in the Spacelab module.
- Janice Voss, Mike Gernhardt and Roger Crouch continue to adjust
their sleep schedules each day to prepare for the end of the mission
Thursday morning at the Kennedy Space Center.in Florida.
- Jim Halsell, Susan Still, Don Thomas and Greg Linteris remain on the
same schedule throughout the flight, waking up at 11 p.m. each day.
- Work today in the laboratory includes plant experiment and protein
crystal growth status checks and work in the glovebox on the
Coarsening in Solid-Liquid Mixtures experiment. During coarsening,
small particles shrink by losing atoms to larger particles, causing
the larger particles to grow. In this experiment solid particles of
tin will grow, or coarsen, within a liquid lead-tin matrix. By
conducting this experiment in space, a greater range of solid volume
fractions can be studied without the effects of convection present in
- The Observable Protein Crystal Growth Apparatus is being used to
characterize proteins and determine the differences that exist in
crystal growth processes in microgravity and on the ground. The
experiment hopes to ultimately optimize growth procedures and
conditions for application in the biochemical field. A major goal of
this experiment is to improve the design and loading procedures and to
eliminate bubble formation, which interferes with crystal growth.
- The dual-shift mission is set to end Thursday morning with favorable
weather forecast for the time of landing.
- Columbia continues to orbit the Earth at an average altitude of 160
nautical miles. All orbiter systems are in excellent shape.
- On Monday, July 14, 1997, 7:00 a.m. CDT, STS-94 Payload Status Report # 21
- Studies of material and combustion science dominated the Microgravity
Science Laboratory -1 investigations in Columbia's Spacelab during the past
- In one area of materials research, the crew conducted an experiment
to study a process that can severely degrade the strength of alloy
products, such as turbine blades in aircraft engines. The Coarsening
in Solid-Liquid Mixtures experiment, led by Dr. Peter Voorhees of
Northwestern University in Chicago, Ill., is providing insight into
processes which can cause metals to weaken or fail.
- The different metals that comprise alloys often have different
freezing points. One metal can begin to solidify before the others,
forming small particles in the mixture. As the solidification process
continues, the mixture begins to coarsen -- the small particles shrink
by losing atoms to larger particles. This results in a lack of uniform
particle distribution that may lead to defects in materials and
products. "We are looking at how the particle sizes change over time,"
said investigator Mark Assel of NASA's Lewis Research Center in
- Exactly how coarsening occurs is still not well understood. On
Earth, gravity causes the heavier liquid metal to sink to the bottom
of the mixture, making it difficult to study the coarsening
process. By studying it in space, the design and control of metals
processing on Earth could be improved.
- During the experiment, a cartridge of lead-tin samples is loaded
into a compact, electric oven in the Middeck Glovebox. The oven heats
the samples to form solid-liquid mixtures. Hundreds of thousands of
solid particles are dispersed in these small samples. Then, the
samples are quenched, rapidly freezing the high-temperature particle
structure. "We are collecting time and temperature data in flight,"
said Assel. "We won't know for sure until we're able to look at the
samples, but we believe the runs were successful, and we expect to get
a lot of good science."
- Sunday, crew members from both the red and blue shifts conducted
runs of the Structure of Flame Balls at Low Lewis-number experiment,
called SOFBALL. The study examines the burning processes of very weak
fuel-air mixtures in near-zero gravity. Payload Specialist Dr. Greg
Linteris conducted a run of the experiment Sunday morning and Mission
Specialist Dr. Janice Voss conducted another run late Sunday night.
- For the first, a mixture of hydrogen, oxygen and carbon dioxide was
used. It was a repeat of a test that was conducted during the
abbreviated STS-83 mission in April. The gas mixture resulted in four
balls of flame. "This run gave us some very interesting results,"
explained project scientist Dr. Karen Weiland of Lewis Research
Center. "Of the four flame balls, only two burned for the duration of
the experiment -- 500 seconds. The other two used up the fuel in that
area and extinguished. This is different than what we observed during
- During the second run, the hydrogen-air mixture was ignited and two
flame balls developed. According to principal investigator Dr. Paul
Ronney of the University of Southern California in Los Angeles, the
experiment is going very well and the science team is very pleased
with the results of the investigation so far.
- At the beginning of his shift Sunday afternoon, Payload Specialist
Dr. Roger Crouch performed a scheduled changeout of the Space
Acceleration Measurement System's hard drive, and last night, Voss
performed a disk changeout in the Quasi-Steady Acceleration
Measurement system. The two systems detect and record the tiny
disturbances in the near-zero gravity environment of the Spacelab.
Science teams rely on the information, downlinked in near-real-time,
to determine the effect of the disturbances on experiments. There are
four acceleration measurement systems operating aboard Columbia.
- Around midnight, Crouch performed a sample exchange in the Large
Isothermal Furnace, initiating a run of the Liquid Phase Sintering
experiment, which is led by Dr. Randall German of Pennsylvania State
University in University Park, Penn.
- In industry, the liquid phase sintering process is used to form very
hard and dense solids -- which, in turn, are used to manufacture
products such as cutting tools, car transmission gears and radiation
shields. Liquid phase sintering consists of causing particles of mixed
metals to bond and form a strong material. During the experiment,
compressed powders of tungsten, nickel, iron and tungsten, nickel and
copper are heated. The nickel, iron and copper melt but the tungsten
does not, resulting in solid-liquid mixtures. Researchers are studying
these mixtures to learn more about the sintering process, specifically
how the particles of the mixtures bond. On Earth, settling of
constituents in the mixture during sintering tends to result in a
- This research is fundamental to powder metallurgy. Investigators
hope to better understand this process and develop techniques that can
be used to lower costs of production and create even better sintered
- Later, Mission Specialist Dr. Donald Thomas began the fifth and
final run of the Diffusion of Liquid Metals study, led by Dr. Toshio
Itami of Hokkaido University in Sapporo, Japan. The investigation is
aimed at determining the diffusion coefficient of liquid tin in
relation to temperature, a very significant measurement for describing
the diffusion process by which liquid metals mix without stirring.
- In the TEMPUS levitating, processing of a sample of iron, nickel and
chromium was initiated Sunday. The Alloy Undercooling Experiment, led
by Dr. Merton Flemings of the Massachusetts Institute of Technology in
Cambridge, Mass., is measuring how fast melted steel mixtures
solidify. During the study, a spherical sample will be positioned in
the facility, melted and then cooled. Results of this research may
improve steel strip casting and welding processes.
- Early this morning, Thomas exchanged the sample in the furnace to
begin another run of a study to gather fundamental measurements of an
undercooled sample of cobalt-palladium. Undercooling is when a liquid
remains fluid when cooled below its normal freezing point. During the
experiment, an electromagnetic pulse is used to squeeze, then release
the sample being levitated in the facility. Instruments record the
oscillations, or movement, of the sample. "This is a new technique,"
explained researcher Bob Hyers of the Massachusetts Institute of
Technology in Cambridge, Mass. "Using this technique we can determine
the surface tension and viscosity, or resistance to flow, of the
sample." This is the first time the viscosity of a cobalt-palladium
alloy has ever been measured. And although the surface tension
measurements of some of the TEMPUS samples are already known, for
others this new technique is pinpointing that figure for the first
- The TEMPUS studies are providing researchers with fundamental
measurements necessary for modeling industrial materials systems
needed to manufacture new and better products. "The studies are going
remarkably well," said Flemings. "They have done everything we hoped
- Today, the Columbia crew is scheduled to perform another run of the
Coarsening of Solid Liquid Mixtures experiment and Linteris will
conduct another run of the flame ball experiment in the Combustion
- On Monday, July 14, 1997, 5:30 p.m. CDT, STS-94 MCC Status Report # 27
- Space Shuttle Columbia continues to provide a reliable ride for the
materials science experiments in the Spacelab module. After 13 full
days in orbit, the spacecraft has no significant problems and
scientists have been able to work uninterrupted in gathering
- A press conference with Columbia's crew is planned for just before 2
a.m. Tuesday morning with reporters at Johnson Space Center, Kennedy
Space Center and Marshall Space Flight Center participating.
- The astronauts heard a special greeting Monday from Alabama
Sen. Jeff Sessions, speaking to them from the payload operations
control center at Marshall Space Flight Center, Alabama.
Sen. Sessions complimented the crew on its work in microgravity
science and its contribution to improving life on Earth.
- In downlink television Monday, Red Team members Jim Halsell, Susan
Still, Don Thomas and Greg Linteris demonstrated the selection of food
available to space travelers aboard the shuttle. The astronauts
showed different methods of packaging and preservation as well as
preparation in space.
- During a mission status briefing today, Lee Briscoe, mission
management representative, said that while there were ample supplies
on board Columbia, no extension of the mission was being contemplated.
Columbia is due to land early Thursday at Kennedy Space Center.
Florida. Briscoe also noted that the crew reported a small "ding" in
one of the orbiter's overhead windows - a = centimeter pit commonly
seen on other missions. Such impacts of tiny debris do not affect the
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