UPTON, NY - Now that they have reached the surface of Mars, NASA's Pathfinder lander and Sojourner rover are quietly examining the Red Planet's geology. But to get there, they had to endure a seven-month journey through the harsh radiation of outer space.
To make sure their vehicles would withstand the trip - and function once they got to Mars - scientists from the Jet Propulsion Laboratory in Pasadena, California, turned to an accelerator at the U.S. Department of Energy's Brookhaven National Laboratory.
Using BNL's Tandem Van de Graaff accelerator, JPL scientists exposed several of Pathfinder's and Sojourner's vital components, including radio parts, to the same kind of radiation bombardment they would encounter in space, to see if they would hold up. The impact of space's energetic atomic nuclei, or ions, on sensitive transistors can cause problems ranging from simple transmission errors to permanent damage and mission failure.
"Before a space mission or satellite lifts off, the only way to find out what the effects of space radiation will be is to subject the components and systems to radiation under controlled conditions," said BNL's Peter Thieberger, who heads the Tandem program.
At BNL, Thieberger said, the JPL engineers learned that ions hitting the radio components did not permanently damage them but caused a condition called 'single event latchup' - a glitch that interrupted their normal operation. By simply turning the power off and then back on, they found, the problem could be solved. Software and timers were then developed to automatically cycle the power whenever this problem occurred on Mars.
BNL's Tandem is one of the world's best-equipped facilities for simulating space's cosmic rays. Over 60 companies, laboratories and agencies from the U.S., Europe and Japan come to the facility each year to test their space hardware, while other companies take advantage of its ion beams for a variety of industrial uses. The accelerator also serves the Laboratory's physics research program by supplying beams of speeding particles and ions to the Alternating Gradient Synchrotron and, soon, to the Relativistic Heavy Ion Collider.
"Our goal is to make efficient use of our specialized equipment and to foster high-tech industrial applications as a complement to our scientific research," Thieberger said.
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