NASA's Phoenix Mars Lander monitored the atmosphere overhead and tested the soil below in this artist's depiction.
Credit: NASA/JPL/UA/Lockheed Martin
Two images of the Phoenix Mars lander taken from Martian orbit in 2008 (left) and 2010 (right). The 2008 lander image shows two relatively blue spots on either side corresponding to the spacecraft's clean circular solar panels. In the 2010 image scientists see a dark shadow that could be the lander body and eastern solar panel, but no shadow from the western solar panel.
Credit: NASA/JPL-Caltech/University of Arizona
SYDNEY: It came to Mars looking for water, and in the end it was killed by ice: NASA has confirmed the Phoenix lander did not survive the long Martian winter.
Just two years after landing on the polar regions of Mars, and only one Martian winter later, the remote lab has given up the ghost.
The Odyssey orbiter began listening for radio transmissions from Phoenix in January 2010, as increasing amounts of sunlight shone on its landing spot in Mars's northern hemisphere. After more than 200 fly-bys and no sign of a response, NASA called it quits on Phoenix.
"The Phoenix spacecraft succeeded in its investigations and exceeded its planned lifetime," said Fuk Li, manager of the Mars Exploration Program at NASA's Jet Propulsion Laboratory in Pasadena, California.
Not expected to survive
Phoenix began its 680-million-kilometre journey in August 2007, arriving on the Red Planet in May 2008 at a latitude equivalent to northern Alaska. The lander worked for five months, two more than originally planned, until too little sunlight reached its solar panels.
Mission scientists correctly predicted that the lander would not survive the Martian winter, which is nearly twice as long as that on Earth (a Martian year is equivalent to 687 days, or slightly less than two years on Earth). Its instruments were not meant to withstand the prolonged stretches of frigid temperatures and frost.
Observations from the Odyssey orbiter had indicated that ice existed close to the surface in these northern latitudes. Phoenix confirmed the presence of water ice using its 2.35-metre-long robotic arm to dig into the subsurface.
The lander was equipped with imaging capabilities and a suite of chemical and geological analysis tools. In its working days in 2008, Phoenix witnessed snow falling and found evidence for climatic cycles in the planet's history.
Calcium carbonate found
Its on-board soil analyser detected calcium carbonate, which indicates interaction with liquid water at some point in the past and perhaps a warmer, more habitable climate in the last few million years.
The biggest surprise, according to researchers, was the discovery of perchlorate, an oxidising salt that can be used as food for some organisms on Earth.
"Although its work is finished, analysis of information from Phoenix's science activities will continue for some time to come," said Li.
The unresponsive lander weathered the Martian winter poorly, sustaining severe ice damage to its solar panels. Hoping to learn about seasonal weather patterns, scientists watched from above using the High Resolution Imaging Science Experiment (HiRISE) camera on the Mars Reconnaissance Orbiter as the panels became encased by carbon dioxide frost.
HiRISE images taken this month suggest that the weight of the ice might have bent or broken the panels.
First analysis of water ice
Though the lifespan of Phoenix was necessarily abbreviated, especially when compared to the robotic rovers Spirit and Opportunity, astrobiologist Malcolm Walter emphasised the importance of exploring Martian poles.
Although scientists have known about water ice on the surface of Mars, said Walter, who directs the Australian Centre for Astrobiology at the University of New South wales in Sydney, "it performed the first in situ analysis of water ice."
Walter said he was most surprised when Phoenix sent back an image of what appeared to be a water droplet on its leg. The presence of salts like perchlorate, which lower the freezing point of water, means that there could be more inhabitable areas on the surface of the planet.
"It opens up a whole new set of possibilities for exploration programs," he said. Other inhabitable water likely exists deeper within Mars, places a robot would have trouble accessing.
Liquid that can support some sort of life might exist near the surface, even if just for short periods of time. "It makes us think about the possibility that there are microbes in the soils of Mars living in these briny environments," said Walter.
Phoenix lander
Had the Phoenix lander been placed somewhere on the equatorial pain of Martian may be this eventuality could have been averted as adequate sunlight prevails all the 687 days.
Talluri Vijai Kumar