The science module of LISA Pathfinder (left) has just separated from its dedicated propulsion module (lower right)

eLISA, to be launched after 2025 as an ESA mission, will detect gravitational waves from space, and gain new insight into their sources. Owing to gravity, the measuring principle of eLISA which essentially consists of test masses floating in space with (nearly) no external disturbances exerted on them can only partly be tested on Earth. Thus, LISA Pathfinder will demonstrate the key technologies for the gravitational wave observatory eLISA in space. Amongst other technologies these are the Drag-free-Attitude-Control-System (DFACS) and the extremely sensitive (interferometric) optical metrology subsystem. Critical parts of this subsystem are essentially developed by the Max Planck Institute for Gravitational Physics/Albert Einstein Institute in Hanover, Germany.
Image: ESA.