by Clare Coppa
You can accurately say ASTM International standards are out of this world.
NASA scientists used ASTM Standards C 1421 and C 1368 to generate data for the design of chamber windows in the International Space Station. A collaboration by sixteen nations, six crews have provided a continuous human presence in space since the Station launched Oct. 31, 2000.
In its Space Station archives, NASA says to prepare for the challenges, engineers and astronauts have been methodically practicing procedures, preparing tools, testing equipment for long-term stays in space, where conditions alternate hourly between freezing and searing.
Enter Jonathan Salem, Ph.D., a materials research engineer with NASA Glenn Research Center, Cleveland, Ohio, who tested materials for the Space Stations Destiny Lab windows with ASTM C 1421, Standard Test Methods for Determination of Fracture Toughness of Advanced Ceramics at Ambient Temperatures, and C 1368, Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress-Rate Flexural Testing at Ambient Temperature.
In the Destiny Lab chambers, Russian cosmonauts and American astronauts do microgravity experiments for biotechnology, fluid physics, combustion, and life sciences. They have infrared cameras that look into these chambers and they need specialty windows that pass certain wavelengths of infrared light, says Salem. They need materials like sapphire or zinc selenide and we used some of the ASTM test standards to get mechanical properties for the design of the windows.
Salem is an award-winning standards developer with ASTM Committees C28 on Advanced Ceramics and E08 on Fatigue and Fracture. Since 1987, he has been shaping NASAs Advanced
Ceramic Laboratory, which includes ASTM standards in Laboratory protocols. Our group basically develops reliability codes for analyzing structures made from brittle materials like ceramics, he says. At the same time, we developed a testing facility to generate data on those materials for input into our computer codes. So my end of it was development of a whole testing facility to get a lot of different properties like strength, fracture, toughness, slow-crack growth, and creep. And in terms of interfacing with ASTM, we sat on the committees to help write some of those standards.
Salem and other researchers are testing foam from the space-shuttle fuel tank with ASTM D 1621, Standard Test Method for Compressive Properties of Rigid Cellular Plastics. Right now, were looking at the strength of the foam on the Orbiter tank under various conditions, he says. The urethane foam keeps the liquid-hydrogen fuel tank cool as it stands between the space shuttles two booster rockets at lift off.
The Advanced Ceramic Laboratory is testing materials for new spacecraft, Salem says: Were starting to test leading-edge materials that could be used in the next generation shuttle-like
vehicle. Ames [NASA Ames Research Center, San Francisco] has designs for this next generation Reusable Launch Vehicle, so theyre considering new materials. Were trying to test some of these materials and help them out from a data standpoint.
Visit NASAs Advanced Ceramics Laboratory Web site.
Copyright 2003, ASTM