In an article posted on Nature News, staff writer Oliver Morton discussed the recent release of six potential landing sites for NASA's Mars Science Laboratory (see above picture). The MSL is a large rover that will assess the past habitability of sites on the Martian surface when it lands in October 2010. The list has been shortened in recent months and includes craters partially filled with sediment, a flood channel and regions which are rich in clay minerals that may date from a time when the Martian surface was much wetter than it is today. The mission has established a buffer zone of 20 kilometers across to account for the many uncertainties associated with landing on Mars. The terrain in that area needs to be flat and smooth.
"If you ask an engineer, they'd like to land in a Walmart parking lot,"said Jack Mustard, a Brown University planetary geologist. Once landed, the rover will need to travel well outside the ellipse to places that feature the type of terrain scientists are looking for. That is where some of the changes to the list of landing sites has changed dramatically. Participants in last month's workshop to choose the candidate sites found that sites where the rover would need to travel more than 10 kilometers to obtain samples would most likely be problematic.
Changes in the way the rover's moving parts will be lubricated raise issues for sites in the southern highlands of Mars, as they reduce the rover's abilities in winter conditions. Nevertheless, scientists shortlisted two southern sites as worthy selections. Holden Crater is one of these sites and it contains what seems to be lake sediments and a delta. The six sites will now be further scrutinized by instruments on NASA's Mars Reconnaissance Orbiter that is currently circling the Red Planet. While this is going on, computer models will assess the risk of winds at the sites to ensure a easy landing. The final decision does not need to be made until the middle of 2009, to make the October 2009 launch.
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