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.
The next scheduled Public Affairs status report will be issued at approximately 6 a.m., July 9.
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