Phoenix is losing power by the day as it gets darker near the Martian north pole. This press release discusses how NASA engineers are trying to keep Phoenix alive for as long as possible. Most notably, they are turning off the heater for the robotic arm, meaning it will probably be unable to move very soon. For more information, check these posts at the Planetary Society blog and Cumbrian Sky. Here’s an excerpt from the press release:

Over the next several weeks, four survival heaters will be shut down, one at a time, in an effort to conserve power. The heaters serve the purpose of keeping the electronics within tested survivable limits. As each heater is disabled, some of the instruments are also expected to cease operations. The energy saved is intended to power the lander’s main camera and meteorological instruments until the very end of the mission.

Later today, engineers will send commands to disable the first heater. That heater warms Phoenix’s robotic arm, robotic-arm camera, and thermal and evolved-gas analyzer (TEGA), an instrument that bakes and sniffs Martian soil to assess volatile ingredients. Shutting down this heater is expected to save 250 watt-hours of power per Martian day.

The Phoenix team has parked the robotic arm on a representative patch of Martian soil. No additional soil samples will be gathered. The thermal and electrical-conductivity probe (TECP), located on the wrist of the arm, has been inserted into the soil and will continue to measure soil temperature and conductivity, along with atmospheric humidity near the surface. The probe does not need a heater to operate and should continue to send back data for weeks.

Throughout the mission, the lander’s robotic arm successfully dug and scraped Martian soil and delivered it to the onboard laboratories. “We turn off this workhorse with the knowledge that it has far exceeded expectations and conducted every operation asked of it,” said Ray Arvidson, the robotic arm’s co-investigator, and a professor at Washington University, St. Louis.