By Matt McGrath

Science reporter, BBC World Service

The spectacular mural on the outside of the Arizona operations centre

The Mars Phoenix Lander is in a race against time and temperatures as it struggles to resolve some key questions about the Red Planet. The onset of the harsh Martian winter means that there is now less Sun to charge Phoenix's batteries. Researchers at the University of Arizona who are in charge of the mission are also struggling with the soil conditions as they try to sift the dirt for evidence of organic chemicals. Please turn on JavaScript. Media requires JavaScript to play. But they hope soon to activate the lander's microphone and record the sounds of Mars for the first time. Housed in a building that could easily pass as a tax office or library, the mission headquarters in Tucson is carving out a little piece of history: Phoenix marks the first time that a Mars Lander has been controlled by a university scientist, not by the boys at Nasa. That scientist is Professor Peter Smith, the principal investigator on the mission. Peter Smith (far right) celebrates the successful landing of Phoenix on Mars

This giant of a man, with a wit as dry as the Arizona desert, is hopeful that Phoenix can tackle two remaining problems before its batteries peter out. "We are still valiantly searching for organic molecules. We'd love to be able to claim that we had found organic materials in the northern plains of Mars. And that's a key and most important ingredient of our search. "But it's also the hardest thing to find. We are pushed right down to the wire in our last samples to try to make that case. So I don't know if that will happen or not, I hope so. That would be big." Indeed it would. Organics can be considered the "feedstock" of biochemistry. In its endeavour to try to show the northern plains could be "habitable", these carbon-rich molecules would represent a big tick mark. "We are also trying to find the isotopic clues that we can find in water in terms of the deuterium to hydrogen ratio," added Professor Smith. Soil samples are dug up and delivered to the onboard labs for analysis That's a real key signature in telling us a lot about the history of water. So if we can get the ratio of the ice and the water vapour just above it, we can see what the connection is between the atmospheric water and the ice underneath the surface. "We think they are in equilibrium and that's why there is ice under the surface. "It's my fervent hope to solve these two questions. Will it happen? I don't know, I'm going to have to live the life and find out." Since it landed on the 25 May, Phoenix has twice had its mission extended. But while it was able to operate for eight or 10 hours a day during the summer, the decline of the Sun in the Martian sky means the lander will struggle to recharge its batteries. "We're pretty sure we can limp along through mid-November," said Professor Smith. "At some point towards the end of that month, we will not be able to heat our batteries - we will not have enough solar energy to heat them and as they get colder and colder they don't work as well. Pretty soon, you can't store any more energy in them; when that happens you are in the death knells. "It's like going to the hospital with someone who is terribly sick and seeing their vital signs getting less and less every day. "It's the same for this spacecraft. If we can make it to the end of the year that would be a great Christmas present; it's nip and tuck." Phoenix team photo: The mission has been run differently to previous efforts

Even as the Sun sets on this mission, Phoenix is still sending back some amazing detail, recently detecting snow falling from the Martian skies. The more we glean about the planet the more Earth-like it seems - and that inevitably raises the question of life on Mars. A question that Peter Smith has grown a little tired of answering. "Who do you think I am? I'm not Nostradamus here, how do I know what's going to happen in 10 years..." I ask him about the idea that life on Earth may have originated on Mars, or perhaps life on Mars might have started from here. Professor Smith is disinclined to speculate, and becomes playful. "You don't ask any of the easy questions do you? How the hell do I know... was God left-handed? How do I know?" The Arizona science team will also be hoping to mark another unique achievement for a mission to Mars. The scientists intend to activate the microphone on the Lander and record the sounds of the planet for the first time. The microphone was originally intended to record the descent of Phoenix but was switched off because of the risk that it could trip a critical landing system. Engineers will now send computer code to the lander to try to activate it. Peter Smith said he hoped it was still in working order. "We'll start slowly, just turn it on and make sure it records sound, and we'll try and make some noise to make sure it's working. We'll try scraping ice with our robotic arm blade and we can bang a few pots or something. Then we'll listen just for the Mars sounds by themselves." When I ask him what he thinks we'll hear on Mars, he responds with tongue firmly planted in his cheek. "I think it's an interesting noise. There may be music. I don't know." Phoenix carries seven science instruments





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