March 1, 2024

How LISA – a gravitational wave observatory in space – will transform our cosmic understanding

The LISA (Laser Interferometer Space Antenna) mission, led by ESA (European Space Agency) with contributions from NASA, will detect gravitational waves in space using three spacecraft, separated by more than a million miles, flying in a triangular formation. Lasers fired between the satellites, shown in this concept art, will measure how gravitational waves change their relative distances. Credit: AEI/MM/Exozet

LISA, a collaborative mission between ESA and

The LISA mission will enable observations of gravitational waves produced by the merger of supermassive black holes, seen here in a computer simulation. Most large galaxies contain central black holes weighing millions of times the mass of our Sun. When these galaxies collide, eventually so do their black holes. Credit: NASA Goddard Space Flight Center/Scott Noble; simulation data, d’Ascoli et al. 2018

NASA will provide several key components of LISA’s instrument suite, along with scientific and engineering support. NASA’s contributions include lasers, telescopes and devices to reduce disturbances caused by electromagnetic charges. LISA will use this equipment to measure precise changes in distance, caused by gravitational waves, over millions of kilometers in space. ESA will provide the spacecraft and supervise the international team during the development and operation of the mission.

Gravitational waves: revealing cosmic secrets

Gravitational waves were predicted by Albert Einstein’s general theory of relativity more than a century ago. They are produced by the acceleration of masses, like a pair of orbiting black holes. As these waves remove orbital energy, the distance between the objects gradually decreases over millions of years, and eventually they merge.

These ripples in the fabric of space went unnoticed until 2015, when LIGO, the Laser Interferometer Gravitational-Wave Observatory funded by the US National Science Foundation, measured gravitational waves from the merger of two black holes. This discovery fostered a new field of science called “multimessenger astronomy,” in which gravitational waves could be used in conjunction with other cosmic “messengers” — light and particles — to observe the universe in new ways.

Along with other ground-based facilities, LIGO has since observed dozens of other Synthetic map of the entire sky constructed from gravitational waves

Gravitational waves from a simulated population of compact binary systems in our galaxy were used to construct this synthetic map of the entire sky. Such systems contain white dwarfs, neutron stars or black holes in tight orbits. Maps like this using real data will be possible once the LISA mission becomes active in the next decade. The center of our galaxy, the Milky Way, is at the center of this all-sky image, with the galactic plane stretching in between. Brighter dots indicate sources with stronger gravitational signals, and lighter colors indicate those with higher frequencies. Larger colored patches show sources whose positions are less known. Credit: NASA Goddard Space Flight Center

LISA will consist of three spacecraft flying in a vast triangular formation that follows Earth in its orbit around the Sun. Each arm of the triangle extends 2.5 million kilometers. The spacecraft will track internal test masses affected only by gravity. At the same time, they will continuously fire lasers to measure their separations to an extent less than the size of a helium.

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