At the poster session last night, amidst the free beer and snacks, there was some confusion (at least to me) about where to try and land on Mars.
Two posters, right next to each other, both addressed potential sites for the Phoenix lander to touch down after it launches late in 2009. The mission’s aim is to dig beneath the surface of Mars and do some indepth chemical analysis of the surface – and any underlying ice.
Three likely candidates had already been identified, all relatively close to one another. Tim Titus from the USGS used thermal inertia measurements of the surface of these three areas and said that none of them had more than about 7cm of topsoil above the ice, and suggested that maybe these weren’t the best places to start digging.
But exhibiting a poster next to Titus’s was Peter Smith, principal investigator on the Phoenix mission. The decision about where to land has already been taken, he says, and the two sites that Titius suggested had the least topsoil had already been ruled out.
But digging deep isn’t the primary objective of the mission, says Smith, “safe landing is the primary consideration.” And Smith is confident that the slightly rugged nature of th planet will give Phoenix a good chance of landing on a crack that will give more than the 7cm of soil Titus predicts.
And will Phoenix give us a chance to find life on Mars? Smith’s personal opinion is “maybe”. He thinks that as the planet’s obliquity, or tilt, changes, the ice will get a bit slushy on the top. If this process cycles back and forth, bacteria could be popped in and out of habitable conditions. And Smith thinks that his favoured landing site offers a good chance to find signatures of life. “Of all the places I’ve heard about this is the place to go,” he says.
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