The joint ESA/NASA precursor mission to test technology for detecting gravitational waves which will be used in the subsequent Evolved Laser Interferometer Space Antenna (eLISA) mission. For eLISA to work properly scientists must be able to guarantee that a solid body can float freely in space completely undisturbed, its trajectory always constant. They will also have to be able to control the spacecraft position with an accuracy of a few millionths of a millimetre. LISA Pathfinder contains two cube-shaped ‘proof’ masses housed in separate vacuum cans. The displacement of the cubes with respect to their housing is measured in three dimensions and the position of the surrounding spacecraft is adjusted so that it remains centred on the proof mass. The LISA Pathfinder launched on 3 December 2015 and was placed at the L1 Lagrangian point of the Earth's orbit. On 7 December, the craft started the extended phase of its mission—an additional six months, during which scientists and engineers pushed the experiment to its limits in preparation for the ESA’s future space observatory of gravitational waves. The mission terminated on 30 June 2017, having successfully demonstrated the technology to build such an observatory.

The LISA Pathfinder spacecraft, launched on 3 December 2015 from Kourou, French Guiana, will help pave the way for a mission to detect gravitational waves.

Credit: ESA