By Alan Fischer
TNAZ Senior Writer
Two images of the Phoenix Mars Lander taken from Martian orbit in 2008 and 2010. The 2008 Lander image (left) shows two relatively blue spots on either side corresponding to the spacecraft's clean circular solar panels. In the 2010 (right) 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
The Tucson-based Phoenix Mars Lander mission was declared officially over Monday, May 24 after repeated attempts failed to contact the spacecraft following a dark, cold winter on the distant planet.
NASA's announcement came two Earth-years after the mission's successful landing on Mars on May 25, 2008 to begin an extended five-month mission seeking evidence of water and elements of life on Mars. A year, or full annual cycle around the Sun, on Mars lasts 687 Earth days, or almost double the time the Earth takes to complete a full cycle of seasons.
The $428 million Phoenix mission found hard chemical evidence of frozen water in material scooped from the Martian northern arctic region during surface operations. The Lander's instruments also discovered unexpected perchlorate, along with other elements and compounds on the planet.
The mission's researchers have not yet been able to say they found elements of life – long-chain hydrocarbons – that would show the planet is or was habitable and able to support basic life forms in the area where the spacecraft landed.
The dead craft, last heard from in November 2008, had been covered with a heavy layer of frozen carbon dioxide during the harsh Martian winter, said Peter Smith, principal investigator of the University of Arizona-led mission.
"There could have been as much of hundreds of pounds of CO2 ice. Those solar panels were never designed for that," Smith said. "We had no scientific requirement to last through winter."
Images from the UA-led High Resolution Imaging Science Experiment, or HiRISE, camera, flying aboard the Mars Reconnaissance Orbiter show the Lander's profile had changed between 2008 and recent weeks, Smith said.
Dust has covered much of the craft. "The Lander has almost disappeared, it's the same color as the surrounding terrain," Smith said.
Despite the dust coating, shadows of the craft seen in the HiRISE before and after images look quite different, leading researchers to believe the craft's solar panels were damaged, he said.
"The pictures explain a lot. The solar panels were not deployed the same way they were before. They probably would not support the weight of the CO2 ice they had to during the winter," Smith said.
The Phoenix Mars Lander's robotic arm is poised to deliver to a testing instrument for analysis a soil sample scooped from the Martian northern arctic region during surface operations in 2008.
Credit: NASA/JPL-Caltech/University of Arizona
"Before and after images are dramatically different," said Michael Mellon of the University of Colorado in Boulder, a science team member for both Phoenix and HiRISE. "The Lander looks smaller, and only a portion of the difference can be explained by the accumulation of dust on the Lander, which makes its surfaces less distinguishable from surrounding ground."
NASA's Mars Odyssey orbiter attempted to contact the Phoenix Lander more than 200 times this year, including 61 pass-over flights last week, but the orbiter detected no responding transmissions from the Lander.
Smith had long said that chances of reviving the tough Martian winter were slim, but a possibility existed that sunlight returning to the area would reenergize the solar powered craft's depleted batteries.
"We were just hoping against all odds it had survived and we could regain contact. That has not been the case," he said.
Had the Martian sun powered up the craft, several instruments were available that potentially could have performed additional scientific testing, he said. And close-up images of the planet's well-documented surface at the landing site following winter would have been quite interesting to researchers, he said.
Smith said it was a bit emotional to have the book finally closed on the mission he led.
"It's part of history now. It's no longer active as a mission," he said. "I feel really proud I was part of the mission, and I'm glad I was able to pull together such a great team. I feel sadness because I no longer have the same opportunity to work with this team anymore."
Researchers, and the public, are still poring over images and data collected during the Phoenix mission, Smith said.
"The data is stored in an archive available to any scientist around the world, as well as the public, so I am looking forward to more discoveries being made," he said.
Information on Phoenix's findings is available at NASA's Planetary Data System site found at
http://pds.jpl.nasa.gov/ Click on the "Mars" quick search prompt and scroll down to the Phoenix search tools for images and data.