Hera is a small spacecraft for deep space possessing comparable autonomy to a self-driving car. Its optimised design has benefited from multiple ESA studies of asteroid missions across the last two decades, most recently the proposed Asteroid Impact Mission.
Powered by solar arrays with a hydrazine propulsion system, Hera will be a small-scale mission in interplanetary terms, roughly the size of a large desk and weighing in at 350 kg, and up to about 870 kg fully-fuelled – which is compact compared to the van-sized, 3 tonne Rosetta comet-chaser.
Hera’s modern design means it will perform its guidance, navigation and control (GNC) tasks through an innovative strategy of data fusion, combining inputs from multiple sensors to build up a detailed picture of its surroundings in space. This would mean, for instance, bringing together the second-by-second visual tracking of distinctive features on the asteroid surface with lidar-based altimeter readings plus on board inertial sensors and star tracker measurements.
Hera has entered its detailed definition Phase B1 with the involvement of industry from Germany, Belgium, Romania, Luxembourg, Sweden, Portugal, Spain, Czech Republic, Austria, Finland, Poland and Switzerland.