ESA Approves LISA Mission to Detect and Study Gravitational Waves from Space
In a groundbreaking development, the European Space Agency’s (ESA) Science Programme Committee has given the green light to the Laser Interferometer Space Antenna (LISA) mission. This mission aims to detect and study gravitational waves from space, marking a significant step forward in our understanding of the universe.
LISA is not just one spacecraft, but a constellation of three. These spacecraft will form an equilateral triangle in space, trailing Earth in its orbit around the Sun. Each side of the triangle will be a staggering 2.5 million kilometers long, more than six times the distance between Earth and the Moon. The spacecraft will exchange laser beams over this vast distance, allowing scientists to detect and analyze gravitational waves.
The launch of the three spacecraft is planned for 2035, with an Ariane 6 rocket set to carry them into space. This ambitious mission is made possible through a collaboration between ESA, its Member State space agencies, NASA, and an international consortium of scientists known as the LISA consortium.
Gravitational waves were first predicted by Albert Einstein over a century ago. These ripples in spacetime occur when massive objects accelerate, shaking the fabric of the universe. Thanks to modern technological advancements, we now have the capability to detect these elusive signals.
LISA’s ability to use laser beams over long distances will allow it to detect gravitational waves from events involving star-sized objects, such as supernova explosions or the merging of hyper-dense stars and stellar-mass black holes. By going to space, LISA will expand the frontier of gravitational studies and probe waves of lower frequencies than what is possible on Earth. This will enable scientists to uncover events on a different scale, reaching all the way back to the dawn of time.
One of the key objectives of the LISA mission is to detect the ripples in spacetime caused by the collision of massive black holes at the centers of galaxies. This will provide valuable insights into the origin and growth of these monstrous objects, shedding light on their role in the evolution of galaxies. Additionally, LISA aims to capture the gravitational “ringing” from the initial moments of the universe, offering a glimpse into the very first seconds after the Big Bang.
Furthermore, LISA will help researchers measure the change in the expansion of the universe by using gravitational waves as a different type of yardstick. This will validate the results obtained through other techniques used by surveys like Euclid. Closer to home, LISA will detect merging pairs of compact objects within our own galaxy, such as white dwarfs or neutron stars. By pinpointing their positions and distances, LISA will enhance our understanding of the structure of the Milky Way.
To detect gravitational waves, LISA will utilize pairs of solid gold-platinum cubes known as test masses. These test masses, slightly smaller than Rubik’s cubes, will be free-floating within each spacecraft. Gravitational waves will cause tiny changes in the distances between these masses, which will be tracked using laser interferometry. This technique involves shooting laser beams from one spacecraft to another and analyzing their superimposed signals to determine changes in distance down to a few billionths of a millimeter.
The spacecraft itself builds upon the success of ESA’s LISA Pathfinder mission, which demonstrated the feasibility of keeping test masses in freefall with astonishing precision. The same precision propulsion system used in ESA’s Gaia and Euclid missions will ensure that each LISA spacecraft maintains its required position and orientation with utmost accuracy.
LISA is set to join ESA’s science fleet of cosmic observers and will address fundamental questions about the physical laws of the universe and its origins. It will work in conjunction with another large mission currently under study by ESA, NewAthena, which aims to be the largest X-ray observatory ever built.
The approval of the LISA mission marks a significant milestone in our quest to unravel the mysteries of the universe. By combining the detection of gravitational waves with our traditional methods of observing the cosmos, we are entering a new era of understanding. Just as the addition of sound transformed motion pictures, the detection of gravitational waves will revolutionize our perception of the universe. With the launch planned for 2035, we eagerly await the groundbreaking discoveries that LISA will bring.
