The European Space Agency (ESA) and OHB System AG have signed an agreement to build LISA (Laser Interferometer Space Antenna). It will search for gravitational waves caused by the most powerful events in the Universe, such as collisions and mergers of pairs of supermassive black holes.
In search of gravitational waves
LISA is ESA’s flagship mission to detect elusive gravitational waves. They are disturbances in the structure of space-time created by any body that has mass and moves with variable acceleration.
To date, scientists have already managed to record several dozen gravitational bursts caused by extreme events such as the merger of black holes and/or neutron stars (their discovery was recognized with the Nobel Prize) using ground-based detectors. However, there is one significant problem. Some types of gravitational waves are harder to observe than others because mergers of different masses produce waves of different frequencies. That is why astronomers want to launch a gravitational observatory into space, which will significantly increase the accuracy of their searches.
From its advantageous position in space, LISA will detect gravitational waves at lower frequencies than is possible from Earth, revealing events on a different scale — dating back to the very beginning of time. This will allow scientists to track how massive black holes merge and grow over cosmic epochs, explore the fundamental nature of gravity, and study the expansion rate of the universe.
As for the Milky Way, LISA will provide new insights into the formation and evolution of tens of thousands of compact binary star systems and deepen our understanding of stellar-mass black holes.
Constellation of three spacecraft
LISA is designed as a constellation of three spacecraft. They will fly in a triangular formation, following Earth in its orbit around the Sun. Each side of the equilateral triangle will be 2.5 million km long.
Each spacecraft will receive a pair of cubes made of pure gold and platinum (so-called test masses), slightly smaller than Rubik’s cubes, floating freely in special housings. Gravitational waves will cause tiny changes in the distances between them.
To record fluctuations in space-time, the mission will track these tiny shifts using a unique laser interferometer. This technique requires infrared laser beams to be directed from one spacecraft to another, and then their signals to be superimposed to determine changes in the distances between masses with an accuracy of several billionths of a millimeter, or shifts smaller than the diameter of a helium atom. And all this at a distance between the spacecraft that is six times greater than the distance between the Earth and the Moon!
Official start of work
The signing of the agreement between ESA and OHB System marked the official start of construction for the mission. It took place at the Paris Air Show. In addition to ESA, an international scientific consortium and NASA are also participating in the project.
According to ESA
