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NASA delays launch of Dawn probe once more

点击量:   时间:2018-01-26 03:02:07

By New Scientist Space and AFP NASA has postponed the launch of the Dawn spacecraft until September, adding an estimated $25 million to the $449 million mission. “Primary reasons for the move were a combination of highly limited launch opportunities for Dawn in July and the potential impact to launch preparations for the upcoming Phoenix Mars Lander mission, set for early August,” the agency said in a statement on Saturday. “A September launch for Dawn maintains all of the science mission goals a July launch would have provided,” NASA added. Dawn’s launch was originally scheduled for Saturday, but was delayed until Monday because of threatening weather at the launch site in Florida, US, and problems with an aircraft meant to observe the launch. NASA was anxious to prevent any of Dawn’s launch delays from affecting the launch of its Phoenix mission to Mars. If Phoenix were to miss its first Florida launch window from 3 to 25 August, it would have to wait two years for its next chance to lift off. Dawn’s eight-year mission is designed to shed light on the earliest moments in the birth of the solar system 4.6 billion years ago by examining the two celestial bodies Ceres and Vesta in the asteroid belt between Mars and Jupiter. Dawn is scheduled to enter orbit around Vesta in October 2011, proceed to Ceres in May 2012 and then begin orbiting Ceres in February 2015 – travelling a total distance of 5.1 billion kilometers. Dawn’s launch window will remain open until the end of October, when the two asteroids begin pulling away from each other, making a rendezvous with both practically impossible. This will be the first NASA mission to orbit two separate bodies. Scientists hope the mission will shed light on why its two target asteroids are so different – the more “evolved” Vesta was once covered by liquid magma oceans and has an iron core,