Laser Interferometer Space Antenna

The Laser Interferometer Space Antenna (LISA) is a planned European space mission to detect and measure gravitational waves—slight ripples in the fabric of spacetime—from astronomical sources. LISA will be the first dedicated space-based gravitational-wave observatory. It aims to measure gravitational waves directly by using laser interferometry. The LISA concept features three spacecraft arranged in an equilateral triangle with each side 2.5 million kilometres long, flying in an Earth-like heliocentric orbit. The relative acceleration between the satellites is precisely monitored to detect a passing gravitational wave, which are distortions of spacetime travelling at the speed of light. Potential sources for signals are merging supermassive black holes at the centre of galaxies, massive black holes orbited by small compact objects, known as extreme mass ratio inspirals, binaries of compact stars, substellar objects orbiting such binaries, and possibly other sources of cosmological origin, such as a cosmological phase transition shortly after the Big Bang, and speculative astrophysical objects like cosmic strings and domain boundaries. The mission was selected by ESA in 2017 and formally adopted in January 2024. Construction began in 2025 following the award of the prime industrial contract to OHB System AG. As of 2026, LISA remains in the development and hardware-construction phase, with launch planned for approximately 2035 aboard an Ariane 6 launch vehicle. The mission will consist of three spacecraft flying in a triangular formation with 2.5 million km arm lengths to detect low-frequency gravitational waves from sources such as merging supermassive black holes and compact binary systems.