Dawn is a retired space probe launched by NASA in September 2007 with the mission of studying two of the three known protoplanets of the asteroid belt, Vesta and Ceres.[1] It was retired on 1 November 2018 and it is currently in an uncontrolled orbit around its second target, the dwarf planet Ceres. Dawn is the first spacecraft to orbit two extraterrestrial bodies,[8] the first spacecraft to visit either Vesta or Ceres, and the first to orbit a dwarf planet,[9] arriving at Ceres in March 2015, a few months before New Horizons flew by Pluto in July 2015.
Dawn entered orbit around Vesta on July 16, 2011, and completed a 14-month survey mission before leaving for Ceres in late 2012.[10][11] It then entered orbit around Ceres on March 6, 2015.[12][13] NASA considered, but decided against, a proposal to visit a third target.[14] On October 19, 2017, NASA announced that the mission would be extended until the probe’s hydrazine fuel supply was used up.[15] On November 1, 2018, NASA announced that the Dawn spacecraft had finally exhausted all of its hydrazine fuel, thus ending its mission. The satellite is currently in an uncontrolled state about Ceres.[16]
The Dawn mission was managed by NASA’s Jet Propulsion Laboratory, with spacecraft components contributed by European partners from Italy, Germany, France, and the Netherlands.[17] It was the first NASA exploratory mission to use ion propulsion, which enabled it to enter and leave the orbit of two celestial bodies. Previous multi-target missions using conventional drives, such as the Voyager program, were restricted to flybys.[4]