Planck was decommissioned in 2013, but data analysis activities continue.
LISA Pathfinder was an ESA technology test mission for the eLISA/NGO mission to search for gravitational waves generated by massive objects such as black holes. NASA contributed one of two payloads, named ST-7.
LISA Pathfinder paved the way for eLISA/NGO. It tested new methods of spacecraft control and determined if laser interferometry is feasible at the level of accuracy required by eLISA/NGO.
LISA Pathfinder placed two test-masses in a nearly perfect gravitational free-fall, for controlling and measuring their motion with unprecedented accuracy. This was achieved through state-of-the-art technology comprising inertial sensors, a laser metrology system, a drag-free control system, and an ultra-precise micro-propulsion system.
All these technologies are essential not only for eLISA/NGO—they also lie at the heart of any future space-based test of Einstein's General Relativity. LISA Pathfinder was launched in 2015.
Final Launch Preparations for LISA Pathfinder: Images of Integration of LISA Pathfinder into VEGA rocket. Photo credit(s): ESA, Manuel Pedoussaut, 2015
The following retired missions were part of the Explorer Program, but their science is closely related to the Physics of the Cosmos Theme.
Hitomi (formerly ASTRO-H) is an X-ray observation satellite that will explore the extreme universe, particularly high energy phenomena around black holes and supernova explosions, and clusters of galaxies filled with high-temperature plasma.
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