Phoenix unlikely to rise — on Mars

The death watch is on for NASA's Phoenix lander, the first spacecraft to sample water on another planet.

Buffeted by dust storms and chilled by temperatures as low as minus 141 degrees Fahrenheit from the impending arrival of the Martian winter, Phoenix is clinging to life, but barely, NASA officials said Friday.

"We knew this was coming," said project manager Barry Goldstein. "It's bittersweet."

Earlier this week, Phoenix fell silent, going into safe mode to save battery power. After failing to answer two wake-up calls from Earth, it flickered back to life long enough Thursday to send a signal to the Mars Odyssey spacecraft orbiting overhead. It then went back to sleep for 19 hours to recharge its batteries.

The lander, however, failed to awaken from its latest sleep Friday, alerting NASA officials to the possibility that the end could be very near.

"It's going down the way we expected," Goldstein said.

He said mission officials will keep watch over the weekend to see if it revives again.

Phoenix, which landed May 25 on the northern Martian plains, has survived two months longer than its planned three-month mission.

While it failed to prove that Mars could or could not harbor life, Phoenix did rack up significant accomplishments. Besides digging into the layer of ice lying just inches under the lander, it uncovered evidence that the ice could have melted in the past, filling in missing gaps in the planet's unfolding water story.

The lander's onboard chemistry lab found that the soil is much more hospitable than many scientists had supposed. "You might be able to grow asparagus very well," a mission scientist said in June.

Phoenix could spring back to life with the next Martian summer, but mission scientists say they are not counting on that.