Space is supposed to offer us a form of escapism from everything in the world, letting us forget the misdemeanors of world leaders or the abhorrent views of others, if only for a brief moment.
So it’s a bit unfortunate that this past year has also been a rather trying one for space fans. In September 2017 we said a teary goodbye to the Cassini spacecraft, our only emissary at Saturn. The planet-hunting Kepler telescope, meanwhile, is on its last legs. And now we're preparing to send off another mission.
That’s because NASA’s Dawn spacecraft, which is in orbit around the dwarf planet Ceres, is also coming to an end. In a statement, NASA said the spacecraft was expected to run out of fuel sometime between August and October, when the spacecraft will stop operating.
“Within a few months, Dawn is expected to run out of a key fuel, hydrazine, which feeds thrusters that control its orientation and keeps it communicating with Earth,” said NASA. That orientation allows Dawn to point its antenna to Earth; without fuel to turn itself, it can’t talk to us.
Dawn was launched back in September 2007, to explore not one but two worlds. In July 2011, it arrived at the large asteroid Vesta, a remnant of the Solar System’s formation. In September 2012 it left Vesta and headed to Ceres, arriving in March 2015.
Ceres was revealed to be an intriguing dwarf planet, with bright spots on its surface that seem to be caused by salts traveling to the surface in a slushy brine – although the exact process is unclear. Images from the spacecraft revealed a fascinating look at these spots, which can be seen at great distances from the world.
Traveling to both of these bodies in the asteroid belt, Dawn became the only spacecraft to ever orbit two separate objects apart from Earth. It was able to do so thanks to its ion propulsion engine, which slowly pushed it from one to the other.
"Dawn's unique mission to orbit and explore two strange new worlds would have been impossible without ion propulsion," NASA’s Marc Rayman, director of the Dawn mission, said in the statement. "Dawn is truly an interplanetary spaceship, and it has been outstandingly productive as it introduced these fascinating and mysterious worlds to Earth."
The spacecraft is currently orbiting at a height of just 35 kilometers (22 miles) above Ceres, its closest orbit yet. It is continuing to gather data and images, and will do so until it runs out of fuel, when it will be left in orbit around Ceres forever.
Dawn may not have grabbed headlines in the way Cassini and Kepler have. But its end will be equally somber, as we say goodbye to our first interplanetary spacecraft to orbit two other worlds.