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![]() Landing site selected for Beagle 2 mission to Mars EUROPEAN SPACE AGENCY SCIENCE REPORT Posted: December 21, 2000 The European Space Agency's Mars Express lander, Beagle 2, will land on Isidis Planitia, a large flat region that overlies the boundary between the ancient highlands and the northern plains. The choice of site was announced last week at a meeting of the Mars Express science working team in ESTEC, Noordwijk, the Netherlands. The region appears to be a sedimentary basin where traces of life could have been preserved, if primitive life really did exist at some time on Mars. "This is the best site given the landing constraints and scientific aims of Beagle 2," said John Bridges from the Natural History Museum, London, who has been assessing several sites on behalf of the project.
Sites previously under consideration include the Chryse Planitia, Candor Chasma and the Elysium plains. Further studies, however, showed that the probe would be unable to function properly at these sites because their latitudes make them too cold in early spring. One channel south of Chryse, Simud Valles, would have been warm enough, but it is too narrow to ensure a safe landing. Another possibility might have been areas of the layered terrain imaged by the camera on NASA's Mars Global Surveyor (MGS) and made public earlier this month. The layering, which is extensive, especially in low-lying areas around the equator, was most likely formed by sediment deposited at the bottom of long-standing lakes or seas, an ideal environment for preserving traces of life. "Unfortunately, this layered terrain is revealed in steep, narrow canyons which are unsuitable because of the landing ellipse size," Bridges told the meeting.
When Beagle 2 has landed, its precise position will need to be measured. One way of doing this will be to time the movement of the shadow of Mars's tiny moon, Phobos, as it passes over the lander during a partial eclipse of the Sun. "In February 2004, the Sun will have a partial eclipse by Phobos. By timing the eclipse, we will be able to pinpoint the lander's position quite accurately," said Tom Duxbury from the Jet Propulsion Laboratory, Pasadena, California, USA, who is helping to characterise the landing site using MGS data. The timing of the landing site decision has been determined by the need of ESA's Mars Express and Starsem's launcher teams to work out a trajectory to enable the spacecraft to deliver Beagle 2 to the desired site. However, further detailed characterisation of the site will continue as new data becomes available from MGS.
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