Illustration of the LISA Pathfinder space probe in space. The LISA (Laser Interferometer Space Antenna) Pathfinder is a joint NASA and European Space Agency (ESA) programme that was launched on 3rd December 2015. It was designed to test the fundamental technologies and instrumentation needed for future gravitational-wave observatories in space. LISA Pathfinder carried two advanced instruments, the LTP (LISA Technology Package) and Disturbance Reduction System (DRS). The LTP is designed to simulate the observational arrangement for the LISA mission. The DRS is an experiment provided by NASAs Jet Propulsion Laboratory in California, which includes also a set of micro-rockets that aim to control the spacecrafts position to within a millionth of a millimetre. LISA Pathfinder was a successful test, and the mission was ended in 2017.