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Sandia Technology logo A quarterly research and development magazine.

Winter 2006/2007
Volume 8, No. 4

SANDIA TECHNOLOGY

Solar tower testing supports NASA plan

metallic water molecules
NASA’s test took place at Sandia’s National Solar Thermal Test Facility, where solar thermal components and systems are developed, researched, and tested. (Photo by Randy Montoya)
NASA tests at Sandia’s National Solar Thermal Test Facility south of Albuquerque, New Mexico, in September produced dramatic bright light, smoke, some flames, and provided information crucial to the next generation of spacecraft.

Using a specially built fixture to hold samples of new ablative materials, researchers from Marshall Space Flight Center, located in Huntsville, Alabama, mounted the test materials on special arms atop the lab’s 200-foot solar tower and exposed them to concentrated solar radiation. The materials scorched in the test were samples of heat shields that NASA plans to use as a new advanced thermal protection system in future spacecraft for aerocapture flight maneuvers.

metallic water molecules
Artist concept of a spacecraft using aerocapture to enter an orbit around Mars. (Image courtesy of NASA)
Aerocapture is a nearly fuel-free maneuver that uses a planet’s atmosphere to capture a spacecraft and place it in its desired orbit. Analogous to a rock skipped across a lake, a spacecraft arriving at a distant planet plunges into the planet’s atmosphere, which slows the craft and changes its trajectory into an elliptical orbit. A key difference between the rock-on-the-lake analogy is the huge amount of friction this maneuver creates in an atmosphere: hence the material tests at 3,500 degrees F at the solar tower.

The solar tower used its 212 computercontrolled mirrors, called heliostats, to track the sun and focus sunlight on the target, simulating the high heat encountered during an aerocapture maneuver.

“It’s worked beautifully,” said Bill Congdon, manager of the ARA Ablatives Laboratory, the Colorado-based manufacturer of the advanced materials for NASA. The structure created on the tower high above the New Mexico desert allowed him to test 2-foot by 2-foot panels of material, subjecting the sample to the intense heat of 1,500 suns. “We wanted to make sure it doesn’t debond — that’s the purpose of this,” Congdon said, noting the charred test panel was still in one piece after a blast of heat.