Flying in formation, they could map the gravitational field of an asteroid or moon by monitoring tiny changes in their relative positions.

ECONOMIST: Picosatellites

Engineers at the General Robotics, Automation, Sensing and Perception (Grasp) Laboratory at Pennsylvania University have developed ways to make small quadrotor robots fly in formation, co-operate and map their surroundings without global positioning systems (GPS) .

BBC: Sky high thinking: Could we all soon own a drone?

Two German radar satellites are now flying in tight formation as they prepare to make the most detailed ever 3D map of the Earth's entire surface.

BBC: German radar satellites fly tight space waltz