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First Mars Express Radar Antenna Finally Deployed

First MarsExpress Radar Antenna Finally Deployed

Peter B. de Selding

Space News StaffWriter

PARIS -- A radar boom antenna aboard Europe's Mars Express satellite that hadfailed to lock into place was successfully deployed May 10-11 after groundcontrollers maneuvered the satellite to expose the boom to the sun, accordingto the European Space Agency (ESA) and European scientists.

Thesuccessful operation makes it more likely that ESA will authorize deployment ofthe second 20-meter-long boom in the coming weeks following an investigationinto the first boom's problem.

Thenon-deployment of the antenna had so worried European science managers thatthey declined to authorize a two-year extension of the Mars Express missionduring a May 9-10 meeting of Europe'sScience Program Committee (SPC).

Risto Pellinen,chairman of the SPC, said May 12 that the SPC probably would have authorizedthe two-year extension, to December 2007, if the balky radar antenna had beensuccessfully deployed before the SPC meeting in Helsinki, Finland. The two-year extension has beenbudgeted at 15.6 million euros ($20.3 million).

Pellinen saidthe SPC is scheduled to meet next in September and is all but certain to agreeto the Mars Express mission extension -- assuming the second radar boom issuccessfully deployed by then. The SPC had feared that Mars Express' otherinstruments might be unable to function fully because of the disequilibriumcaused by flying with a single, partially deployed 20-meter antenna, Pellinensaid.

Working withNASA's Jet Propulsion Laboratory, which supplied the radar antenna, MarsExpress program managers concluded that the longer-than-expected storage of theboom might account for the fact that one of its 13 joints, or hinges, failed tolock into place during the May 8 deployment.

ESA said in aMay 11 statement that the Kevlar and fiberglass boom material might have beenaffected by the prolonged storage at cold temperatures.

Mars Expressreached Mars orbit in December 2003. Its radar antennas were not immediatelydeployed because of concerns that there might be of a whiplash effect createdby unfurling the two 20-meter antennas. That concern did not surface untilafter the satellite had been launched and once it reached Mars ESA officialswanted to give the satellite's other instruments time to operate before runningthe risk of damaging them during the radar deployment.

Moving thesatellite to fully expose its non-deployed element to the sun apparently workedby heating the affected joint and allowing it to lock into place. The radarantennas are designed to search for water up to a depth of several kilometersbeneath the surface of mars.

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Charles Q. Choi
Charles Q. Choi

Charles Q. Choi is a contributing writer for and Live Science. He covers all things human origins and astronomy as well as physics, animals and general science topics. Charles has a Master of Arts degree from the University of Missouri-Columbia, School of Journalism and a Bachelor of Arts degree from the University of South Florida. Charles has visited every continent on Earth, drinking rancid yak butter tea in Lhasa, snorkeling with sea lions in the Galapagos and even climbing an iceberg in Antarctica. Visit him at