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Thursday, July 3, 1997 6 a.m. CDT
07.03.97
 
STATUS REPORT : STS-94-04s
 
 
STS-94 Mission Science Report # 4s
 
 

Overnight, the crew of the Microgravity Science Laboratory aboard Space Shuttle Columbia activated the final experiment facility and began additional experiments, among the more than 30 investigations to be conducted during the 16-day mission.

Wednesday evening, Payload Commander Dr. Janice Voss activated the Droplet Combustion Apparatus -- an enclosed chamber that will support an experiment studying the combustion of fuel droplets. She performed a full check out of the experiment’s hardware and set up a VCR and camcorder that will record and bring video of the experiment to the ground-based research team.

By studying droplet combustion in the near-weightlessness environment of Earth orbit, scientists hope to collect information on burning rates of flames, flame structures and conditions of flame extinction. Detailed knowledge of how fuel droplets burn is an important factor in the design and improvement of furnaces for material processing, heating homes and businesses, producing power by gas turbines as well as combustion of gasoline in vehicle engines.

"A major amount of the energy produced around the world comes from burning fuels," said Dr. Vedha Nayagam, project scientist for the Droplet Combustion Experiment, from the NASA Lewis Research Center in Cleveland, Ohio. "By studying burning fuel droplets in space and comparing the results to theoretical models, we can learn about the chemistry of these fuels. This will help us to burn these fuels more efficiently and minimize pollutants."

After the Electromagnetic Containerless Processing Facility -- known by its German acronym, TEMPUS -- completed a 20 hour pumping-down process to establish a vacuum within the facility’s chamber, Payload Specialist Dr. Roger Crouch powered on the facility and performed a complete checkout of the hardware. Using ground-based computer commanding, the TEMPUS experiment team worked through the night and into the early morning hours to get the facility into the right condition to begin processing samples.

“TEMPUS researchers whose samples were processed during the minimum duration flight in April learned how their samples performed in the microgravity environment of space. Using this knowledge, they were able to fine-tune their experiments for this flight,” said Dr. Jan Rogers, TEMPUS project scientist with Marshall Space Flight Center.

During an experiment run to process a sample of Zirconium, the facility’s temperature control apparatus did not work as expected. Troubleshooting efforts are underway.

Before beginning his daily exercise period, Crouch installed a camera and VCR to document an experiment called Internal Flows in a Free Drop, which was conducted later in the multi-purpose Glovebox facility. He also configured the experiment’s computer and conducted a calibration run.

Handover to the red shift science team occurred at 1 a.m. CDT. The red shift crew consists of Mission Specialists Dr. Donald Thomas, Commander Jim Halsell, Pilot, Susan Still and Payload Specialist Dr. Gregory Linteris. The seven-member crew is split into two shifts so that scientific work can continue around the clock, maximizing use of the precious time in orbit..

After completing his daily exercise period, Thomas conducted the Internal Flows in a Free Drop experiment in the Glovebox. He deployed free single liquid drops of varying sizes 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.

Acoustic positioning is an important technique used in the containerless processing of materials. This investigation, led by Dr. Satwindar S. Sadhal of the University of Southern California in Los Angeles, will allow 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.

At 4:15 a.m. CDT, the first order of business for Payload Specialist Linteris was to prepare the Combustion Module -1 for a second fire-related experiment in the Laminar Soot Processes investigation. The module, developed by the Lewis Research Center in Cleveland, will test hardware and experiment techniques to be used on the International Space Station -- demonstrating its ability to accommodate a variety of combustion experiments.

Linteris performed a propane-fueled soot experiment. This run of the soot experiment had a lower chamber pressure, an increased flow of fuel and a longer burning time than the first run, conducted Wednesday afternoon. It produced a “beautiful and steady flame,” according to Linteris.

“We will use the first few experiment runs to set parameters for the remaining runs. The crew did an outstanding job of setting and running the two tests. Determining the settings for future runs will improve the efficiency of the experiment operations which are designed to determine under what conditions soot is produced by flames and what the composition of soot is,” said Dr. Gerard Faeth of the University of Michigan in Ann Arbor.

Later, Linteris initiated a sample in the Large Isothermal Furnace to test a specially designed experiment cartridge that will be used to conduct two of the metallic alloy diffusion studies. The studies will use the shear cell method to determine the rate of diffusion.

The shear cell method involves two column samples of different concentrations of chemical dopants, or very dilute alloys. The columns are melted, then rotated into contact with each other for a specific period of time. The resulting single column is sheared into segments and cooled. Measurements are made post-flight to determine concentration of the dopants in the segments. From these measurements, the rate of diffusion is calculated.

Using the shear cell method, this study may also reveal the rate of diffusion of tin and lead-tin-telluride. Findings could lead to a better understanding of the diffusion process and improved metal alloys and products. The experiment’s lead scientist is Dr. Shinichi Yoda of the National Space Development Agency of Japan in Tsukuba, Japan.

Ahead, Linteris will perform a shear cell rotation of the sample processing in the Large Isothermal Furnace and will conduct a third run of the soot experiment in the Combustion Module -1. Thomas will transfer the ASTRO/Plant Generic Bioprocessing Apparatus from the Shuttle’s Middeck to the EXPRESS Rack.

The next scheduled Public Affairs status report will be issued at approximately 6 p.m., July 3.

 

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