080710 Phoenix struggling with icy payload

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Phoenix struggling with

icy payload
BY DR EMILY BALDWIN
ASTRONOMY NOW

Posted: July 10, 2008

NASA's Phoenix Mars Lander's science and engineering teams are still testing methods to get an icy sample into the Robotic Arm scoop for delivery to the Thermal and Evolved Gas Analyser (TEGA).

The hard, icy Martian surface that Phoenix has uncovered is proving to be a difficult target to scoop up. "We expected ice and icy soil to be very strong because of the cold temperatures,” says Ray Arvidson of Washington University. “It certainly looks like this is the case and we are getting ready to use the rasp to generate the fine icy soil and ice particles needed for delivery to TEGA.”

This image was acquired on Sol 44 of the Phoenix mission (July 7) and shows the current status of scraping in the Snow White trench. Image: NASA/JPL-Caltech/ University of Arizona/Texas A&M University.

Phoenix has three tools on the scoop that can help access the icy soil – a backhoe with a titanium blade, a tungsten carbide blade, and a high-speed rasp – but so far just the scraping tools have been tested as a possible technique for collecting up an ice-rich sample for analysis. Even though Phoenix piled up two sets of 50 scrapes into small piles at the bottom of the ‘Snow White’ trench on Monday, it could not get the material into its scoop, images returned from Mars on Monday night confirmed.

"It's like trying to pick up dust with a dustpan, but without a broom," says Richard Volpe, an engineer from NASA's Jet Propulsion Laboratory on Phoenix's robotic arm team.

The engineers are now focusing on the use of the motorized rasp within the robotic arm scoop to access the hard icy soil and ice deposits. They are conducting tests on Phoenix's engineering model at The University of Arizona to determine the optimum ways to rasp the hard surfaces and acquire the particulate material produced during the rasping, with the ultimate aim of delivering this material quickly to TEGA before the ice’s composition changes once it is exposed to the Martian atmosphere.