Washington, Oct 29 : Engineers with NASA''s Phoenix Mars Lander mission are trying to extend the lander''s survival by gradually shutting down some of its instruments and heaters.

Originally scheduled to last 90 days, Phoenix has completed a fifth month of exploration in the Martian arctic. 

As expected, with the Martian northern hemisphere shifting from summer to fall, the lander is generating less power due to shorter days and fewer hours of sunlight reaching its solar panels.

At the same time, the spacecraft requires more power to run several survival heaters that allow it to operate even as temperatures decline.

"If we did nothing, it wouldn''t be long before the power needed to operate the spacecraft would exceed the amount of power it generates on a daily basis," said Phoenix Project Manager Barry Goldstein of NASA''s Jet Propulsion Laboratory, Pasadena, California. 

"By turning off some heaters and instruments, we can extend the life of the lander by several weeks and still conduct some science," he added.

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.

According to Ray Arvidson, the robotic arm''s co-investigator, and a professor at Washington University, St. Louis, "We turn off this workhorse with the knowledge that it has far exceeded expectations and conducted every operation asked of it." (ANI)