WASHINGTON Engineers taking long-distance care of NASA's Phoenix Mars Lander mission are planning to start turning off its heaters one by one and let it freeze to death.
The lander has been sending back data for five months -- far longer than the original three months it was supposed to last. But as the Sun's light fades, it will start to lose power.
"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," the U.S. space agency said in a statement on Tuesday.
The lander has recorded snowfall, scraped up ice and found that the dust on the surface of Mars chemically resembles seawater, adding to evidence that liquid water that may have supported life once flowed on the planet's surface.
"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," Phoenix Project Manager Barry Goldstein of NASA's Jet Propulsion Laboratory in California said in a statement.
"By turning off some heaters and instruments, we can extend the life of the lander by several weeks and still conduct some science."
NASA said four survival heaters will be shut down one at a time to save power, starting on Tuesday and over the coming weeks.
The Phoenix team has left a thermal and electrical-conductivity probe thrust into the soil to measure temperature, humidity and conductivity. The probe does not need a heater and should continue to send back data for weeks.
Earlier on Tuesday, NASA said its Mars Reconnaissance Orbiter has found evidence of opals -- a new category of minerals whose discovery suggests that liquid water remained on the planet's surface a billion years later than scientists believed.
It would have played an important role in shaping the planet's surface and possibly provided a place for life to evolve.
"This is an exciting discovery because it extends the time range for liquid water on Mars and the places where it might have supported life," said Scott Murchie of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.
"The identification of opaline silica tells us that water may have existed as recently as 2 billion years ago."
(Reporting by Maggie Fox; Editing by John O'Callaghan