"Today, we celebrate the end of our Dawn mission - its incredible technical achievements, the vital science it gave us and the entire team who enabled the spacecraft to make these discoveries", Thomas Zurbuchen, associate administrator of NASA's Science Mission Directorate in Washington, D.C., said in a statement. "Dawn is no longer able to maintain the position at which its antenna is directed to Earth to communicate with mission control, and not able to change the orientation to batteries charged from solar panels".
Because of the life-on-Ceres question, NASA chose to keep Dawn spinning in orbit rather than sending the probe down to crash onto the dwarf planet's pockmarked surface. The mission was technically canceled twice before the spacecraft got off the ground, but Dawn launched in September 2007 with its sights set on the asteroid Vesta and the dwarf planet Ceres, chosen for how little they resembled each other.
In 2015, Dawn became the first to visit a dwarf planet and go into orbit around two destinations beyond Earth.
Dawn will remain in orbit for at least 20 years, and engineers have more than 99% confidence the orbit will last for at least 50 years, it said.
Dawn discovered a number of intriguing bright spots on Ceres. "It carried humankind on a truly unbelievable deep space adventure with stunning discoveries". Such spaceflight feats were made possible by Dawn's superefficient ion engines, mission team members have said. Strict planetary protection protocols govern how NASA can dispose of crafts like Dawn, as they do not want to interfere with the chemistry on Ceres.
Some of the spacecraft's major discoveries include showing that dwarf planets are capable of hosting liquid oceans, as well as allowing researchers to compare bodies at different distances from the Sun and map out how location has affected their formation and evolution.
The early birthplace of bodies was key to how the early solar system organised and evolved.
Dawn also spotted a 2.5-mile-high (4 km) "lonely mountain", by far the tallest surface feature on the dwarf planet.
So, while the mission plan doesn't provide the closure of a final, fiery plunge - the way NASA's Cassini spacecraft ended a year ago, for example - at least this is certain: Dawn spent every last drop of hydrazine making science observations of Ceres and radioing them back so we could learn more about the solar system we call home.
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