STS-94 Day 12 Highlights

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On Saturday, July 12, 1997, 7:00 a.m. CDT, STS-94 MCC Status Report # 22 reports:

Around-the-clock science investigations continue aboard Columbia with the focus this morning on developing better methods for the efficient use of fossil fuels while reducing emissions and air pollutants.

The seven-astronaut crew of STS-94 - divided into two teams - provides on-orbit assistance to ground controllers throughout the mission conducting these, and as many as 30 other, experiments in the Spacelab pressurized module which is emulating what laboratory work will be like on the future International Space Station.

The Red team of astronauts began its twelfth flight day in space at about midnight with mission Commander Jim Halsell and Pilot Susan Still watching over orbiter systems while Mission Specialist Don Thomas and Payload Specialist Greg Linteris oversee science operations.

Much of Thomas' day is focused on the Fiber Supported Droplet Combustion experiment in the Spacelab glovebox to assist investigators in what could eventually lead to more efficient utilization of fossil fuels and reduction of air pollutants. Halsell and Still supported the experiment work by periodically turning off the shuttle's thruster jets to provide a 'quiet' environment for Thomas' work.

Linteris worked on another experiment through the first half of his workday called the Structure of Flame Balls at Low Lewis-number that in the future may lead to the development of improvements in lean burning internal combustion engines - an advancement that holds promise in providing increased efficiency and reduced emissions.

Earlier this morning, Halsell and Still entertained questions from a television station in his home state of Louisiana, with the focus on Halsell's background and the mission's objectives.

The Blue team of Janice Voss, Mike Gernhardt and Roger Crouch turned the reins over to the Red team about 1 a.m. today and is scheduled to wake up about noon.

On Saturday, July 12, 1997, 7:00 a.m. CDT, STS-94 Payload Status Report # 19 reports: (MET 10/17:58)

The Shuttle Columbia crew and the Microgravity Science Laboratory are rounding the final turn and heading into the home stretch of their 16-day run of conducting science in space. According to Mission Scientist Dr. Mike Robinson, things continue to go well. "The science teams have been working very hard, and they're happy with what they've seen so far," said Robinson.

The science team for the flame ball experiment was happy with what it saw last night, reporting two more series of successful runs. The investigation, being conducted in the Middeck Glovebox, examines the combustion properties of very weak fuel mixtures in near-zero gravity. Payload Commander Dr. Janice Voss completed one set of runs last night and Payload Specialist Dr. Gregory Linteris completed another early this morning. "The experiment is going extremely well and the science team is getting fantastic data," said lead investigator Dr. Paul Ronney of the University of Southern California in Los Angeles.

During the experiment, the chamber is filled with very weak combustible gases, the mixture is ignited with a spark, and information is gathered on the resulting flame balls. "We're interested in learning which mixtures will burn and which ones won't," said Ronney, "and the limits of combustion -- where the weakest possible flames can exist."

Also, Ronney reported that during last night's burns, instruments measured very little disturbance in the microgravity environment of the test facility. "The flame is being driven by hot gases surrounding the flame and these gases are extremely sensitive," said Ronney, "so it's important to minimize disturbances in the environment."

Since little is known about the burning processes of these flames, findings will be used to verify which, if any, existing theoretical models are accurate. "We want a steady flame so we can easily compare it to computer models on the ground," said Ronney. "Any disturbances make that comparison more difficult."

Another combustion science experiment, which studies the burning process of large fuel droplets, was conducted in the Middeck Glovebox. Payload Specialist Dr. Roger Crouch completed a series of tests last night and another series was completed this morning by Mission Specialist Dr. Donald Thomas. "We are ahead of schedule," said investigator Dr. Ron Colantonio of NASA's Lewis Research Center in Cleveland, Ohio. "We've been able to complete a few extra runs and we're getting good science."

During the experiment, a thin fiber is used to position a large droplet of fuel in the viewing area of the chamber. The droplet is then ignited and information is gathered on the burn rates, flame shape and radiation emitted. "The amount of energy lost through radiation has never been measured before," said Colantonio. "People have guessed what that is. We're actually going to measure it."

Information from this study can also help improve theoretical models of combustion. It will also complement what is being learned from the Droplet Combustion Experiment, also being conducted aboard Spacelab. That experiment is studying the burning processes of heptane fuel droplets. Like the Droplet Combustion Experiment, the Fiber Supported Droplet experiment also burns heptane fuel droplets, but in an environment of oxygen and hydrogen, rather than oxygen and helium. "By changing one parameter, we will be able to measure the effect of the different combinations of elements in the environment," said Colantonio. "This will be very beneficial to the Droplet Combustion science team."

Overnight, two shear cell rotations of the sixth and final run of an investigation to study the diffusion process of tracers, or impurities, in melted germanium were conducted. Crouch performed the first rotation last night and a second rotation was performed by Pilot Susan Still early this morning. "It looks like we saved the best for last," said lead scientist Dr. David Matthiesen of Case Western Reserve University in Cleveland, Ohio. "We're optimistic the results of this test will be good."

The experiment involves two samples, one of pure germanium and one of germanium with an additive. The first shear rotation brings samples into contact with other. After diffusing, or mixing, for a certain amount of time, the resulting single sample is sheared into segments and cooled for post-flight analysis.

Germanium is an element widely used as a semiconductor. Knowledge gained from this study may be used to improve the performance of electronic components made from semiconductor materials, such as transistors and integrated circuits.

Last night in the TEMPUS facility, Crouch initiated an experiment to measure the surface tension and viscosity of undercooled liquid metals. During the experiment, an electromagnetic pulse is used to squeeze, then release a sample -- in this case, liquefied gold -- being levitated in the facility. Researchers then gather information on the oscillations, or changes in the sample's shape. From these measurements researchers are able to determine the surface tension and viscosity -- or resistance to flow -- of the sample. This is a new technique which is allowing researchers to measure some of the fundamental properties of liquid gold for the first time.

One aim of the investigation is to achieve improvements in materials processing techniques on Earth, in turn making possible better products.

Ahead, Thomas will continue to conduct the Fiber Supported Droplet Combustion experiment in the Middeck Glovebox and Linteris will begin the third phase of the Droplet Combustion Experiment. This phase of the study is designed to map the burning characteristics of a heptane fuel droplet at one-quarter atmospheric pressure, a fourth of the atmospheric density on Earth, at varying oxygen concentrations.

On Saturday, July 12, 1997, 5:30 p.m. CDT, STS-94 MCC Status Report # 23 reports:

Space Shuttle Columbia continues to provide a solid platform for microgravity science experiments being conducted in the Spacelab module in the orbiter's cargo bay. The STS-94 mission Saturday passed the two-thirds complete mark with another full day of experiments in combustion and materials processing science. Science investigations by the crew Saturday related primarily to the study of combustion processes in space and experiments in the Electromagnetic Containerless Processing Facility. Taking a brief break from science operations, Red Team members Jim Halsell, Susan Still, Don Thomas and Greg Linteris sent downlink television of their choice to the ground, answering Internet questions with a videotaped lesson in combustion science. Thomas explained the goals of some of the experiments, how droplets burn in the absence of gravity and the significance of the work to life on Earth. Still took her blood pressure and pulse on-orbit and compared them to pre-flight readings. Linteris demonstrated how liquids behave in a low-gravity environment.

The three also were interviewed by WBRZ-TV in Baton Rouge, La. The Red Team members took the opportunity to explain some of the combustion science work under way and commented on the quick turnaround between the shortened first flight of the MSL payload in April and the reflight. STS-94 is the fastest reflight of a crew and payload in shuttle history, making up for the first attempt which was cut short by suspect performance in a fuel cell.

The Blue Team of Janice Voss, Mike Gernhardt and Roger Crouch awoke shortly before 1:30 p.m. CDT to begin its 12th flight day. The Red Team will awaken again about 11 p.m. CDT and take the duty shift about 1 a.m. The next status report will be issued about 6 a.m. CDT Sunday.

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