Science
The main goal of LISA is to use direct measurements of gravitational waves to study astrophysical systems and to test Einstein's theory of gravity. The existence of gravitational waves is inferred from observations of the decreasing orbital periods of several binary pulsars, such as the famous PSR 1913+16. However, gravitational waves have not yet been directly detected on Earth because of their extremely small effect on matter. Observing them requires two things: a very strong source of gravitational waves – such as the merger of two black holes – and extremely high detection sensitivity. The LISA instrument should be able to measure relative displacements with a resolution of 20 picometers over a distance of 5 million kilometers, yielding a strain sensitivity of better than 1 part in 1020. Due to its sensitivity in the low-frequency band of the gravitational-wave spectrum, LISA will detect waves generated by binary stars within our galaxy (the Milky Way); by binary, supermassive black holes in other galaxies; and by extreme mass ratio inspirals ("EMRIs"), in which a stellar-mass black hole is captured by a supermassive black hole.
Read more about this topic: Laser Interferometer Space Antenna
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