Electromagnetic formation flight testbed (EMFF). The EMFF testbed is designed to test alternative forms of propulsion for future formation-flying space satellites. Two superconducting coils surround test equipment which is attached to a base suspended by a gas supply. The base spins in response to varying electromagnetic forces. Current experimental formation-flying satellites rely on tanks of propellant gas to manoeuvre, which require frequent replacement. An electromagnetic system allows groups of satellites to manoeuvre by repelling or attracting one another without the need for a gas propellant. Photographed in 2005 at the Massachusetts Institute of Technology (MIT), USA.