Mars Lander Presumed Dead, Despite "Lazarus Mode"
for National Geographic News
|November 10, 2008|
After five fruitful months, the Phoenix Mars Lander is believed to have sent its last dispatch to Earth, said NASA scientists who announced the end of the mission Monday.
There is a slight chance, though, that the lander's energy-saving "Lazarus mode" could allow Phoenix to be rise again after the long Martian winter, albeit in a limited capacity.
(Pictures: Phoenix Lander's Search for Mars Water.)
The craft might have lasted till December 2008, but frigid temperatures and lack of sunlight—largely due to a dust storm—are draining the lander's solar-powered batteries, perhaps permanently.
Researchers haven't heard a peep from the craft since November 2.
"At this time, we're pretty convinced that the vehicle is no longer is available for us to use," said Doug McCuistion, director of NASA's Mars Exploration Program.
But Phoenix scientists are in no mood to brood.
Launched in August 2007, the Phoenix Mars Mission was designed to study the water history and potential for life in the ice-rich soil near Mars's north pole.
The mission accomplished "99 percent of what we proposed to do," said mission principal investigator Peter Smith of the University of Arizona.
The lander has exceeded expectations overall, he said. The mission was to last 90 sols, or Martian days, one of which lasts 24 hours and 39 minutes. Phoenix stopped communicating after 150 sols.
"It's really an Irish wake, rather than a funeral," Mars Exploration Program director McCuistion said. "We should celebrate what Phoenix has done and what the team has done."
The Phoenix Mars Lander has now entered "Lazarus mode," its batteries draining completely each day. In the Bible, Jesus Christ is said to have raised a man named Lazarus of Bethany from the dead.
"It is like pulling the plug on your computer system, and each day you have to reboot, bringing the spacecraft up to a prelaunch state where it doesn't know the local time," Phoenix principal investigator Smith said.
For a time, the craft was still spending about two hours each day transmitting to the orbiters that relay Phoenix's data to Earth. Then the lander would rest, collecting as much sunlight as possible to recharge the batteries.
Now, there's no evidence the batteries are recharging at all.
Flurry of Finds
The first mission to the Martin Arctic, Phoenix landed on Mars on May 25 and sent back a flurry of finds.
The lander confirmed what scientists had suspected from data sent by the earlier Mars Odyssey orbiter: Water ice lies just under the red planet's surface.
And its investigations of Martian soil—using digging tools and onboard ovens—proved telling, the Mars Exploration Program's McCuistion said.
"We have never experienced soil that behaves like it does in the Martian Arctic," he said. "It's sticky, it creates clumps, and it's difficult to handle. That's new for us."
In other Martian landscapes, landers and rovers had encountered dustier soils, he said.
Principal investigator Smith added that Phoenix had uncovered alkaline soil and "a whole suite of nutrients—the kinds of things you take in your vitamin pill." This also indicates that water evaporates on the Martian surface. Phoenix had also found perchlorate, which is used by microbes on Earth as an energy source.
A Canadian weather station aboard the craft discovered bizarre weather, including frost on the ground and snow falling from Martian clouds.
Will Phoenix Rise?
Without battery power for the heaters, the spacecraft must weather temperatures near minus 220 degrees Fahrenheit (minus 140 degrees Celsius) for six months of Martian winter, Smith said.
Furthermore, carbon dioxide ice could destroy or bury the solar panels, killing Phoenix's ability to recharge.
There is a glimmer of hope, however faint, that the same Lazarus programming that's allowed Phoenix to take advantage of waning Martian sunlight could also allow the lander to rise from hibernation in the Martian spring—October 2009 here on Earth.
"There is a possibility that it could try to come alive and contact us again. The chances are probably low," NASA's McCuistion said.
Many of the instruments aboard Phoenix have been used up, but "it might be interesting" to employ the craft a while longer as a Mars weather station, McCuistion added.
The Phoenix craft will remain on the Martian surface indefinitely—along with a DVD time capsule the lander brought with it.
The Visions of Mars DVD was developed by the Planetary Society in Pasadena, California. Made of silica glass, for durability, the DVD contains the names of about 250,000 people from more than 70 countries, as well as samples of Earth literature, art, and music.
On Earth, Phoenix lives on in small mountains of data still awaiting analysis on scientists' desks and computer screens.
"We have a very unusual, 150-day weather report from Mars now. That has yet to be fully mined," principal investigator Smith said.
And there's still hope for the holy grail. Evidence of complex organic molecules, the stuff of life on Earth, has eluded researchers throughout the mission.
"What we're looking for, of course, is a habitable zone on Mars," Smith said. "I think we have the data that's going to show that."
|© 1996-2008 National Geographic Society. All rights reserved.|