STS-94 Day 8 Highlights

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On Tuesday, July 8, 1997, 6:00 a.m. CDT, STS-94 MCC Status Report # 14 reports:

With more than 40 percent of their mission completed, Columbia's seven astronauts are continuing around-the-clock science investigations in the Spacelab module, focusing on how various materials and liquids change and behave in weightlessness.

After a brief handover with their blue team counterparts just after midnight, the red team members -- Commander Jim Halsell, Pilot Susan Still, Mission Specialist Don Thomas and Payload Specialist Greg Linteris -- took over responsibility for the management of science operations aboard the Shuttle.

After completing his daily exercise period, Halsell conducted status checks and performed video documentation of some of the Microgravity Science Laboratory experiments and activities in the Spacelab. The first part of Pilot Susan Still's day involved monitoring orbiter systems and working an in-flight maintenance procedure with the Shuttle Amateur Radio Experiment (SAREX). Following a daily lab planning session, Thomas continued experiments in the Glovebox unit and Linteris worked with the Combustion Module.

After they take a lunch break, Thomas and Linteris will continue the same science efforts with the addition of work with the Large Isothermal Furnace. Halsell and Still will continue watching over Shuttle systems, performing some air monitoring checks as well. They also will conduct some communication sessions with the SAREX unit.

A possible SAREX communication session between the crew aboard Columbia and astronaut Mike Foale aboard the Mir space station may take place just before 2 p.m. CDT at 7/00:57 MET. If it happens, the linkup between the two spacecraft will be accomplished by routing Foale through ham radio operators at the Johnson Space Center and into mission control. The Shuttle and Mir will not be passing close to one another for this communications opportunity. The conversation between Mir and Columbia will depend on Foale's schedule.

The STS-94 Blue team, Payload Commander Janice Voss, Mission Specialist Mike Gernhardt and Payload Specialist Roger Crouch, will be awakened just after 11 a.m. CDT and will take over responsibility for science and orbiter operations shortly after 1 p.m.

On Tuesday, July 8, 1997, 7:00 a.m. CST, STS-94 Payload Status Report # 11 reports:

As the Microgravity Science Laboratory mission approaches the half-way mark of its planned 16-day flight, researchers are reporting overall good results so far, and one of the combustion science research teams, which completed its experiment last night, says the information it gathered on this mission is even better than hoped for.

Payload Commander Dr. Janice Voss performed the last run of the Laminar Soot Processes experiment in the Combustion Module last night, and according to lead scientist Dr. Gerard Faeth of the University of Michigan at Ann Arbor, "it was gorgeous; the best of them all." Between both missions, the one in April and this one, 17 tests were completed, three more than originally scheduled. "Every one worked and yielded good data," said Faeth. "That was beyond my wildest dreams."

Researchers learned that achieving non-buoyant, or steady, flames is a lot tougher than thought and so was predicting some of the flame burning characteristics. "After the first few runs we got some starting points, and it was easy to predict when the soot would be produced," said Faeth, "but predicting how much soot was much more difficult."

The science team will now spend at least the next 12 months poring over information gained from the study. "There is a tremendous amount of data that comes out of each test," said Faeth, "so there's plenty to do." Findings from the investigation may lead to a better understanding of how to contain unwanted fires, burn fuels more efficiently and reduce pollutants. "The study is a good example of a process found in a diesel engine," said Faeth.

Later, Voss removed and stowed the soot experiment hardware and began preparing the Combustion Module for an investigation known as Structure of Flame Balls at Low Lewis Number, or SOFBALL. The study is designed to determine under what conditions a stable ball of flame can exist and if heat loss is responsible in some way for the stabilization of the flame ball during burning.

This experiment is designed to provide researchers with a better understanding of the combustion process and will help to improve theoretical models. "Combustion models give different results for these types of flames," said investigator Dr. Paul Ronney of the University of Southern California in Los Angeles. "This is an acid test to show which, if any, current combustion models should be used."

Three runs of the Droplet Combustion Experiment were completed overnight. The experiment is collecting information on burning rates of flames, flame structures and conditions under which flames are extinguished. The experiment involves burning a droplet of heptane fuel at different atmospheric pressures. Last night's run was at one-half atmospheric pressure, half of that on Earth, in a mixture of helium and 25 percent oxygen.

"We had one excellent run," said project scientist Dr. Vedha Nayagam of NASA's Lewis Research Center in Cleveland, Ohio. "It is more difficult to ignite the droplets at lower pressure, but we think we have the procedure down now and it is just a matter of coordination. Timing is critical."

Results of this investigation will also provide researchers with a better understanding of how combustion occurs and may lead to cleaner and safer ways to burn fuels as well as more efficient methods of generating heat and power on Earth.

In the TEMPUS levitating furnace facility last night, an experiment run was ended when the vapor levels reached the maximum amount allowed for the sample. The experiment is studying glass formation in zirconium-based metals. The experiment had been given additional run time, however, so although it ended early it completed the full originally scheduled run.

Later, Payload Specialist Dr. Roger Crouch performed a scheduled changeout of the TEMPUS side view camera, then activated an experiment to study the nucleation, or point at which solidification from the melted state begins, in liquid zirconium. During the experiment, the melts will be cooled below their freezing points. Researchers are interested in determining the temperatures at which nucleation occurs and how many nucleations occur at each temperature. Nucleation is an important chemical and industrial process.

Later, Crouch performed a shear cell rotation of the sample processing in the Large Isothermal Furnace. This procedure is part of an experiment to study the diffusion process of tracers, or impurities, in melted germanium, an element widely used as a semiconductor and alloying agent.

During the shear cell rotation, samples of pure germanium and germanium with an impurity are rotated into contact with each other. After an opportunity to mingle together, or diffuse, the resulting single sample is sheared into segments and cooled for post-flight analysis.

Findings from materials science experiments aboard Spacelab, including investigations under way in the TEMPUS and Large Isothermal Furnace facilities, may lead to improved techniques of processing materials on Earth and in turn better products.

This morning, Mission Specialist Dr. Donald Thomas is conducting a study of capillary- driven heat transfer devices in the Middeck Glovebox. The goal is to examine the performance of these devices in microgravity and improve their reliability. Similar devices may be used to transfer heat from electrical systems to radiators. Capillary heat transfer is attractive for use in space because it requires no power to operate and such devices cost less because they weigh less.

Payload Specialist Dr. Gregory Linteris is continuing to prepare the Combustion Module for the first SOFBALL test. Ahead, Linteris will initiate the second of six planned runs of the diffusion study under way in the Large Isothermal Furnace and complete a scheduled procedure to change out a disk of one of the microgravity measurement systems on board Columbia.

On Tuesday, July 8, 1997, 5:00 p.m. CDT, STS-94 MCC Status Report # 15 reports:

The Space Shuttle Columbia continues to orbit the Earth in excellent condition, providing a stable and reliable platform for more than 30 separate scientific investigations being conducted on board.

The seven crew members, working in two teams to provide 24-hour science support to the investigations, are devoting most of their attention to working with the Microgravity Science Laboratory experiments. Earlier today, Pilot Susan Still discussed procedures for stowing one of those experiments, a plant growth investigation called Astro-PGBA, with the flight control team in Houston.

Astro-PGBA is currently located in the Express Rack in the Spacelab module, where it will remain until the crew begins stowage activities in anticipation of a planned July 17th landing at the Kennedy Space Center. For both launch and landing, Astro-PGBA is stowed in two middeck lockers. Once on orbit, the experiment was moved to the Express Rack in the Spacelab module, and two empty lockers from the Express Rack were moved to the middeck. At that time, the crew encountered some difficulty in removing a long-handled allen wrench from a bolt in the lower left hand corner of the middeck stowage position. Earlier today, Still made a careful survey of the area today, checking all four bolts, removing and reinstalling lockers and reported to the flight control team that she had no problem with the locker or bolts. Based on Still's input, Astro-PGBA will be stowed in its planned stowage location for entry.

Shortly before 2 p.m. today, Mission Commander Jim Halsell, Payload Commander Janice Voss and Mission Specialist Mike Gernhardt spoke with astronaut Mike Foale aboard the Mir space station during a 10-minute ham radio contact that was routed to Columbia's crew. At the time of the conversation, the two spacecraft were about 1,100 miles apart with Mir tracking southeast from Canada over much of the mid-western United States before passing over Florida and the Atlantic Ocean. Columbia, meanwhile, was skirting the coast of Central America and crossing over the northern portions of South America throughout the conversation. The astronauts discussed the docking of the Progress resupply vehicle to Mir, with Foale's Mir 23 crew mate Alexander Lazutkin announcing that "Christmas had arrived." Foale also invited Columbia's crew over for a cup of tea, after a fresh supply arrived on the Progress.

The Blue team, Payload Commander Janice Voss, Mission Specialist Mike Gernhardt and Payload Specialist Roger Crouch, assumed responsibility for orbiter and science operations shortly after 1 p.m. today and continue their support of combustion investigations in the Spacelab module. The Red team; Halsell, Still, Mission Specialist Don Thomas and Payload Specialist Greg Linteris, will awaken just after 11 p.m. to mark the start of Flight Day 9 for the Microgravity Science Laboratory Mission.

On Tuesday, July 8, 1997, 6:00 p.m. CST, STS-94 Payload Status Report # 12 reports:

Crew members aboard the Space Shuttle Columbia were busy today, conducting more combustion, materials and fluid science experiments as the Microgravity Science Laboratory Mission approached its mid-point.

This morning Mission Specialist Dr. Don Thomas performed an experiment which studies capillary-driven heat transfer devices. The experiment is already shedding new light on how these devices work and is offering explanations as to why they occasionally fail in spacecraft applications.

The investigation examines the device's ability to transfer heat away from a particular location. In the future these devices may be used to transfer heat from electrical equipment to radiators on spacecraft. The benefits of these systems are that they weigh less than conventional units because they operate on evaporation and condensation, and are more economical because they do not require power.

This morning, Payload Specialist Dr. Gregory Linteris attempted to ignite the first flame balls of the mission in the Structure of Flame Balls at Low Lewis-number experiment, but the run produced only "flame kernels," explained project scientist Dr. Karen Weiland of NASA's Lewis Research Center in Cleveland, Ohio.

"What resulted this morning, when the igniter was sparked, were not really flames," said Weiland. The reason was that this sample was much weaker than the mix that burned during the STS-83 mission. On the previous mission, flame balls burned for 500 seconds -- dramatically longer than investigators had expected.

Weiland said the science team is not totally surprised that flame balls did not develop in today's first experiment run because the mix is approaching the flammability limit. Another run scheduled for this evening will test a richer fuel mix that should be easier to ignite.

The experiment, conducted in the Combustion Module 1, is designed to determine under what conditions a stable flame ball can exist and if heat loss is responsible for the stabilization of the flame ball during burning. The experiment also examines how various mixture properties, such as fuel/oxidizer concentrations and temperature, affect the flame-ball's stability and existence.

"In pre-mixed gases used for combustion on Earth, we simply don't understand the mechanisms of flame extinction (what makes the fire go out), what stabilizes it, or what keeps it going," said Dr. Paul Ronney of the University of Southern California in Los Angeles. "These stationary spherical flame balls are the simplest to study, learn from and then apply to Earth applications."

Results of the experiment could lead to improvements in lean-burn internal combustion engines, increased efficiency and reduced emissions. Other benefits may include improved fire safety for mine shafts, chemical plants and spacecraft.

Midday, before the end of his shift, Linteris changed a disk the Quasi-Steady and Space Acceleration Measurement system. The system is one of four on board the Shuttle which detects and records the small, yet unavoidable disturbances in the near-zero gravity environment of the Spacelab. Science teams rely on the information, down-linked in near-real-time, to determine the effect of the disturbances on experiments.

After his daily exercise period, Payload Specialist Dr. Roger Crouch performed the Internal Flows in a Free Drop experiment. This investigation, led by Dr. Satwindar S. Sadhal of the University of Southern California in Los Angeles, are allowing researchers to assess the potential for a containerless, non-contact mixing method that could lead to improvements in chemical manufacturing, petroleum technology, cosmetics and food sciences.

Crouch deployed free single liquid drops of water, and water and glycerin, of varying sizes into the Glovebox and then positioned the spinning drops using sound waves or acoustic manipulation. Tracer particles inside the drops give scientists the ability to map the internal flows taking place as the drops are manipulated by sound waves.

Processing of a liquid zirconium sample underway in TEMPUS will continue for another 14 hours. Researchers are studying nucleation, or the point at which solidification begins. So far the sample has been melted and then cooled below its freezing point -- while still a liquid -- more than 70 times. Researchers are interested in determining the temperatures at which nucleation occurs and how many nucleations occur at each temperature. Nucleation is an important chemical and industrial process.

Ahead, after a scheduled half day break, Voss will resume combustion investigations, performing the second in a series of flame ball experiments and Crouch will perform another run of the experiment that examines the positioning of fluids using sound waves.

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