The candidate Hera mission to the two-asteroid Didymos system will include two briefcase-size spacecraft, European Space Agency (ESA) officials announced last Monday (Jan. 7).

"We're very happy to have these high-quality cubesat missions join us to perform additional bonus science alongside their Hera mothership," Hera manager Ian Carnelli said in a statement. [The Greatest Asteroid Encounters of All Time!]

"Carrying added instruments and venturing much closer to our target bodies, they will give different perspectives and complementary investigations on this exotic binary asteroid," Carnelli added. "They will also give us valuable experience of close proximity operations relayed by the Hera mothercraft in extreme low-gravity conditions. This will be very valuable to many future missions."

The binary asteroid system consists of the 2,550-foot-wide (780 meters) Didymos and its 525-foot (160 m) satellite, dubbed "Didymoon."