STS-107 CM-2 / SOFBALL science summary
Paul D. Ronney,
Principal Investigator
University of
Southern California
This summary was
written before the loss of Columbia.
Click here to read about my perspective on the loss of Columbia and its crew
Click on a link
below to view crew tribute produced by NASA-Glenn:
Low resolution (33 MB) High resolution (72 MB)
1 flame ball
moving in corkscrew pattern |
Another
corkscrew test |
2 large flame
balls |
3 flame balls |
9-ball test (Camera 1 view) Only first 15 minutes of test shown; we wonÕt know which one is Kelly until post-mission. |
9-ball test (Camera 2 view) Only first 15
minutes of test shown; we wonÕt know which one is Kelly until post-mission. |
The objective of the SOFBALL experiment was to study weakly burning flames in hydrogen-oxygen-inert and methane-oxygen-inert mixtures in a configuration called Òflame ballsÓ that were originally predicted by the Russian physicist Ya. B. Zeldovich in 1944 but not seen experimentally until 1984 in short-duration drop tower experiments conducted by Prof. Ronney. Because flame balls are steady, convection-free, spherically symmetric and occur in fuels with simple chemistry, they represent the simplest possible interaction of chemistry and transport in flames. In this sense flame balls bear a similar relationship to combustion research that the fruit fly does to genetics research.
A total of 39 tests were performed in 15 different mixtures, resulting in a total of 55 flame balls, of which 33 were named by the crew. The total burn time for all flames was 6 1/4 hours. Since flame balls are extremely sensitive to gravitational acceleration, all tests were conducted during orbiter free drift periods. Microgravity levels were measured using OARE. The quality of the microgravity was found to be excellent (average accelerations less than 1 micro-g for most tests).
Among the accomplishments of the experiment were
Several totally new results were found, for example
The data obtained during the mission will keep combustion scientists busy for many years to come and will help lead to the development of cleaner, more fuel-efficient engines as well as improved methods for spacecraft fire safety assurance.
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Radiometer signal showing flame ball oscillations |
Image of flame balls in a hydrogen-oxygen-sulfur hexafluoride mixture at 3 atmospheres pressure. Click here to see video. |