The space-borne gravitational wave detector, LISA, was studied in great detail as a collaborative mission between NASA and ESA. Ultimately, NASA and ESA decided not to proceed with the mission: LISA was not the highest ranked mission in the 2010 Decadal Survey and funding constraints prevented NASA from proceeding with multiple large missions, and ESA did not select LISA as the first large mission in its Cosmic Vision Programme. In 2013, ESA identified a gravitational wave observatory as the third large mission in its Cosmic Vision Programme, and NASA is studying a role in that mission.
LISA would have been a gravitational wave telescope similar to a Michelson interferometer. Three identical spacecraft were to be flown in an Earth-trailing orbit, forming the vertices of an equilateral triangle with arm spacing of 5 million kilometers (around 3 million miles). Laser beams between these spacecraft would have enabled measurement of the relative displacements between these spacecraft, with the incredible accuracy of several picometers. A picometer is equal to one trillionth of a meter. With this level of accuracy, scientists could measure the tiny distortions of spacetime caused by a passing gravitational wave.
Gravitational waves move throughout the Universe. They are produced by such cataclysmic events such as the merging of supermassive black holes. Unlike electromagnetic radiation (for example radio waves), gravitational waves penetrate through all matter, thereby allowing us to see back to the beginning of the Universe without dust or other matter hiding things.
Gravitational wave observations could enable studies of: the formation and growth of massive black holes and their host galaxies; structure formation; stellar populations and dynamics in galactic nuclei; compact stars; the structure of our Galaxy; General Relativity in extreme conditions; cosmology; and searches for new physics.
Last updated: June 4, 2015