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JPL Postpones Aiming Maneuver For Mars Polar Lander
By Greg Clark
Staff Writer
posted: 05:15 pm ET
06 October 1999
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Mission controllers at NASA's Jet Propulsion Laboratory are postponing for at least ten days, a trajectory correction maneuver scheduled for the Mars Polar LanderA course-correction maneuver for the Mars Polar Lander has been postponed, while mission controllers redesign the mission. The routine fine-tuning of the polar lander's course was originally scheduled for Thursday, but now will not be conducted until Oct. 18 or 20, said spokeswoman Mary Hardin of NASA's Jet Propulsion Laboratory. The lander's mission was complicated by the loss two weeks ago of the Mars Climate Orbiter, which was to have served as a communications relay link for the lander. Mission designers had hoped to use the climate orbiter as a communications uplink in order to conserve the electrical power that long-distance transmission to Earth requires. Communication and data-transfer through the orbiter also would have increased the amount of time each martian day the lander would be in direct contact with Earth. Now, the polar lander will have to communicate directly with controllers on Earth. Engineers need to reconfigure the communications commands and send new information to the lander so it can use its antennas to transmit and receive directly from Earth. The lander is not in danger of becoming the victim of the same mistake that doomed the Mars Climate Orbiter, according to Hardin, because the lander does not have a component called a reaction wheel. That precision steering instrument was the focus of a misunderstanding that resulted in controllers who, confusing metric and English units, sent the orbiter on an errant trajectory that put it too close to Mars. Without a reaction wheel, there is no possibility for the same mistake to create a problem, Hardin said.
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