The Mars Phoenix Lander has been a shining success for NASA. Not only did the craft reach Mars and land successfully, it also found ice in the martian soil and saw snow in the sky. But the Phoenix is now racing against time to complete more of its groundbreaking research before the harsh martian winter brings its death, said the project's science leader, Peter Smith of the University of Arizona, at the first session of the Popular Mechanics Breakthrough Conference in New York today. "It's down to the wire," Smith said at a panel discussion with two other Phoenix project leaders, Ed Sedivy from Lockheed Martin Space Systems and Barry Goldstein of NASA's Jet Propulsion Laboratory.
The Phoenix is NASA's first lander to visit the polar regions of the planet, sitting at about 68 degrees latitude, Sedivy said. But just like the northern regions on Earth, days are getting shorter there. Just after the 90th martian day of the Phoenix's visit, Goldstein said, the sun began to dip below the horizon, and now every day since then the lander's solar arrays have been able to take in less and less energy. By the end of November, Phoenix probably won't have sufficient power to operate. "It'll get so cold that the vehicle will literally freeze to death," he said.
Smith said he hopes the last few weeks of the Phoenix's mission provide excitement like the day this summer that it sent some pictures of ice that the Lander uncovered just inches below the martian surface. "When we saw the picture, we all said, 'Holy cow!,'" Smith said. The team was also shocked when Phoenix discovered perchlorate in the soil. Many reports said that the discovery of these organic salts were a bad sign for those seeking life on Mars. But not so, Smith said. While we have no idea what life on Mars would look like, scientists assume it would look like life on Earth. In that case, both ice and perchlorate are good signs. There are micoorganisms on earth that use perchlorates as an energy supply, and the scientists had hoped to find something similar on Mars. Hopefully, Smith said, the craft will have enough time before its death to make more stunning discoveries--in a couple weeks, he said, the scientists will activate the landers' microphone and send back the first sounds of Mars.
With the Phoenix's mission now ending, it leaves many unanswered questions for future Mars missions, and for those hoping to find evidence of life is what happened to the atmosphere. The red planet once possessed a denser atmosphere that it does today, which allowed liquid water's presence on the surface. "Where did that atmosphere go, and why?" Sedivy asked. He is already working one of the next mission to Mars, MAVEN, which could start to provide the answer.
MAVEN, the Mars Atmosphere and Volatile Evolution craft, is scheduled for a 2013 launch, and would then enter orbit the next year and take readings of present-day atmospheric loss. The Phoenix's findings also leave the scientists with other questions, like how deep the martian ice goes. "Is it 10 feet? 100 feet? 1,000 feet?" Smith asked. "Who knows?" Smith also hopes someday to learn how much of the planet is hiding subterranean ice, and Goldstein said that if the SUV-sized Mars Science Laboratory actually launches next year--there have been rumors of its cancellation or delay, but NASA recently recommitted to the project's timetable--then it could potentially search the soil in Mars' equatorial region for ice.
One last thing that the Phoenix could teach future Mars missions is about the uncertainty of landing there. The Phoenix Lander suffered a strange problem at the outset, according to Goldstein, when it landed at the far end of its projected landing area rather than right in the middle. He said that NASA was able to record 200 data points per second, which allowed them to reconstruct the Lander's descent and find that there was en error in the modeling data for the martian atmosphere--as a result, Phoenix's angle of descent was off by a degree, which generated lift and nearly carried it out of its projected landing area. He said this finding could help NASA plan more accurate martian landings in the future.
Those future missions may or may not find more evidence supporting the idea that Mars holds or once held life, Smith said, but anybody hoping life is out there has to be encouraged by the Phoenix Lander's mission. Not only did the lander find ice in the soil and snow in the atmosphere, it found that the martian soil had a pH of 8 or 8.5, close to that of Earth's oceans. "It's more like an Earth environment than we ever would've guessed," Smith said.