Photos: Gravity experiments in space
Source:
NASA
The International Space Station has played host to a clutch of mini-satellites
These mini-satellites are football-sized devices that are part of a project called Synchronized Position Hold Engage Re-Orient Experimental Satellites (SPHERES).
This trio has been used to test control programmes that allow satellites to fly in formation with minimal human intervention. Individual space satellites could be co-ordinated to make powerful telescopes.
Better control procedures could also enable spacecraft to dock autonomously, an ability that could be useful for assembling objects in orbit.
The International Space Station may still be under construction, but microgravity research has been under way for decades. Here is a round-up of some of the most notable experiments.