Some spacecraft just can鈥檛 sit still. After exploring asteroids Vesta and Ceres, NASA鈥檚 Dawn probe may fly off to a third destination.
Dawn was launched in September 2007, orbited Vesta for 14 months in 2011 and 2012, and then flew on to orbit Ceres in March 2015, where it remains today.
It is the first ever spacecraft to visit two different asteroids, a hop-on, hop-off tour made possible thanks to Dawn鈥檚 low-thrust ion drive, which uses electricity to spit out xenon ions rather than conventional rocket fuel.
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This summer, Dawn鈥檚 Ceres mission will officially end. But earlier this week, principal investigator Chris Russell of the University of California at Los Angeles and his team sent a proposal to NASA for an extension.
Secret destination
Spacecraft at the end of their life are normally parked in an out-of-the-way orbit, or crash land on the body they have been聽studying. That鈥檚 the plan for the Rosetta probe, which will touch down on comet 67P/Churyumov-Gerasimenko later this year, but that fate won鈥檛 be possible for Dawn.
鈥淭he spacecraft has not been sterilised, so we aren鈥檛 allowed to touch down on the surface of Ceres,鈥� says Russell. Strict planetary protection rules forbid us sending Earth microbes to other worlds. 鈥淚nstead, we want to go the other way, away from Ceres, to visit yet another target.鈥�
Given the small amount of xenon fuel remaining, the list of potential destinations is probably not too long, but Russell is keeping it a secret for now. 鈥淎s long as the mission extension has not been approved by NASA, I鈥檓 not going to tell you which asteroid we plan to visit,鈥� he says. 鈥淚 hope a decision won鈥檛 take months.鈥�
