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March 21, 2006

CRISM Reaches the Red Planet

NASA's newest spacecraft to Mars is now circling the red planet - with a powerful Applied Physics Laboratory spectrometer poised to scan the Martian surface in unprecedented detail. The Mars Reconnaissance Orbiter capped a 7-month, 310-million-mile (499-million kilometer) journey when it entered orbit around Mars on March 10. For the next several months it will use a series of calculated dips into Mars' atmosphere (a process called "aerobraking") to move into a nearly circular orbit that extends 158 miles to 199 miles (254 kilometers to 320 kilometers) above the surface.

That's prime viewing range for the APL-built Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), a key part of the orbiter's six-instrument science payload. CRISM's data will help identify sites most likely to have contained water, and which would make the best potential landing sites for future missions.

The instrument will look for the residue of minerals that form in the presence of water, the "fingerprints" left by evaporated hot springs, thermal vents, lakes or ponds on Mars when water could have existed on the surface. It will also monitor seasonal changes in dust and ice particles in the atmosphere, supplementing data gathered by the orbiter's other instruments and providing new clues about the Martian climate.

The CRISM team conducted three successful checkouts of the instrument during the cruise to Mars, which started when the orbiter launched last Aug. 12. "The instrument is working very well," says CRISM Principal Investigator Scott Murchie, of APL.

This summer, the CRISM team will continue planning for the next round of spacecraft checkouts and instrument calibrations - which begin when the aerobraking phase ends in September - and refining the software it will use to operate the instrument and collect data. The mission's primary science phase, set to last two years, starts in early November.