Orbiting Earth In Search Of Failure
It's a mission where failure will be success -- and that's exactly what NASA engineers are hoping for. They anticipate failures in six experiments on the NASA Space Radiation Electronics Testbed, a payload now orbiting Earth aboard the Space Technology Research Vehicle-1-d. The satellite was launched Nov. 15 on an Ariane 5 rocket from French Guiana.
Managed by the Marshall Space Flight Center in Huntsville, Ala., the experiments will enable engineers to better evaluate the effects of space radiation on advanced microelectronics. Radiation can cause trouble for printed circuit boards and other electronic equipment on satellites.
"It may sound strange, but we're actually hoping electronic components will fail," said Donna Hardage, project manager for the NASA Space Radiation and Electronics Testbed at the Marshall Center. "That's the best way we can accurately know their limits.
"We're monitoring and evaluating several commercial off-the-shelf electronic components to determine how they hold up under the severe exposure to radiation," Hardage added.
Engineers will use telemetry data received from the satellite to improve designs for spacecraft circuitry. The experiments also will help meet NASA's goals of reducing costs, weight, power requirements and production time for future spacecraft while improving their reliability.
The experiment package is part of a joint mission involving NASA, the U.S. Department of Defense's Ballistic Missile Defense Organization, the U.S. Air Force, the United Kingdom's Defence Evaluation and Research Agency and several other international organizations.
The mission -- planned to last for at least one year -- is corresponding with the solar maximum that occurs every 11 years -- a period when solar and radiation activity is at its peak.
As it circles the Earth every 10.5 hours, the satellite passes through the Van Allen Belts, zones of intense radiation trapped in Earth's magnetosphere and extending several thousands miles into space. There, the satellite encounters the trapped proton region and the inner and outer electron belts. Charged particles in these belts cause serious problems for satellite operations - such as deterioration of components and interruption of electronic signals.
The package is about the size of a 40-quart ice chest and weighs 220 pounds (100 kilograms.)
The satellite is in a highly elliptical orbit to expose it to greater radiation. The orbit is 385.3 miles (620 kilometers) at perigee, its closest point to the Earth, and 24,230 miles (39,000 kilometers) at apogee, its farthest point from Earth. "We're pushing these components to their limits. If they survive, that tells us a lot. But if they fail, it tells us even more," Hardage said.
"All of the commercial off-the-shelf items have been tested on the ground, but with exposure to only one energy range and just one energy particle," she said. " We want to see how they respond to continual radiation as well as events such as solar flares and cosmic rays."
Engineers will use the collected data to improve models for designing and manufacturing electronics for space missions. The investigators are expected to publish the results in the spring of 2002.
Here are brief descriptions of the experiments:
The Space Technology Research Vehicle is funded by the U.S. Department of Defense's Ballistic Missile Defense Organization, Washington, D.C., with development and integration performed by the U.S. Air Force Research Laboratory, Kirtland Air Force Base, New Mexico.
The United Kingdom's Defence Evaluation and Research Agency, in Farnborough, England, was responsible for the payload integration and launch of the Space Technology Research Vehicle-1-d.
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Shrinking Size And Cost Of Future Spacecraft While Increasing Safety
Kirtland AFB - Nov. 21, 2000
Two experimental Air Force payloads launched last week Nov 14 aboard the British Defense Evaluation and Research Agency's Space Technology Research Vehicle (STRV-1) may lead to smaller, cheaper spacecraft that can also detect space-based radiation harmful to sensitive spacecraft electronics.