Phoenix Mission Update: Course Tweak

Phoenix Mars Lander Status Report: Tasks En Route to Mars Include Course Tweak, Gear Checks. By the Jet Propulsion Laboratory,
October 30, 2007.

"NASA's Phoenix Mars Lander, launched on Aug. 4 and headed to Mars, fired its four trajectory correction thrusters Wednesday for only the second time. The 45.9-second burn nudged the spacecraft just the right amount to put it on a course to arrive at the red planet seven months from today.

At Mars, Phoenix will face a challenging 7-minute descent through the atmosphere to land in the far north on May 25, 2008. After landing, it will use a robotic digging arm and other instruments during a three-month period to investigate whether icy soil of the Martian arctic could have ever been a favorable environment for microbial life. The solar-powered lander will also look for clues about the history of the water in the ice and will monitor weather as northern Mars' summer progresses toward fall.

The second course adjustment had been postponed a week to allow time for carefully returning the spacecraft to full operations after a cosmic-ray strike disrupted a computer memory chip Oct. 6. Experiences with previous spacecraft have shown hits by cosmic rays are a known hazard in deep space. The Phoenix spacecraft properly followed its onboard safety programming by putting itself into a precautionary standby state when the event occurred. Mission controllers then followed step-by-step procedures to understand the cause and resume regular operations.

"Our engineers responded in a very careful and deliberate manner. Since this was a very well-understood anomaly, it was a good experience for the team," said Phoenix Project Manager Barry Goldstein ..."

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