The European Space Agency (ESA) Scientific Program Committee approved the mission today LISA (Laser Interferometer Space Antenna), the first scientific attempt to detect and study gravitational waves from space. The scientific contribution in Spain is led by the Institute of Space Sciences (ICE-CSIC) and the Institute of Space Studies of Catalonia (IEEC).
Through this step, officially called “adoption”, ESA recognizes that the mission concept and technology is sufficiently advanced and gives the green light for the construction of the instruments and spacecraft. The Work will begin in January 2025once a European industrial entrepreneur has been selected.
LISA is not just one spacecraft, but a constellation of three. These follow the Earth's orbit around the Sun and form a equilateral triangle extremely precise in space. Each side of the triangle will be 2.5 million kilometers long (more than six times the distance between Earth and the Moon), and over this distance the spacecraft will exchange laser beams. He begin of the three spacecraft is planned 2035on an Ariane 6 rocket.
Setting the universe film to music
Just over a century ago, Einstein made the revolutionary prediction that when massive objects accelerate, they shake Space-time tissueThis creates tiny waves called gravitational waves. Thanks to modern technological advances, it is now possible to detect these elusive signals.
Across the universe, LISA will detect ripples in spacetime caused by the collision of giant black holes at the centers of galaxies. This will allow the team to trace the origin of these objects, map their growth to masses millions of times larger than the Sun, and determine the role they play in the evolution of galaxies.
“LISA is an effort that has never been attempted before. Use Laser beams at distances of tens of kilometersGround-based instruments can detect gravitational waves from events involving star-sized objects, such as supernova explosions or mergers of hyperdense stars and stellar-mass black holes. To push the boundaries of gravity studies, we need to go into space,” he explains. Nora Lützgendorflead scientist of the LISA project.
Echoes of the universe's first moments
The mission is prepared to capture that Gravitational noise from the early moments of our universewhat current theories predict, and offers a direct insight into the first seconds after the Big Bang.
Since gravitational waves also contain information about the distance of the objects that emit them, LISA will help measure the change in the expansion of the universe using a different criterion than the techniques of the Euclid space mission and other studies, thus validating the results. .
In our galaxy, LISA will detect many merging compact objects such as white dwarfs or neutron stars, giving us a unique insight into the final stages of the evolution of these systems. By determining their position and distance, LISA will improve our understanding of the structure of the Milky Way.
To detect gravitational waves, LISA will use massive cubes of gold and platinum, called test masses (slightly smaller than Rubik's cubes), floating freely in a special enclosure at the heart of each spacecraft. Gravitational waves will cause small changes in the distances between masses in different spacecraft and the mission will track these variations using laser interferometry.
This technique involves firing laser beams from one spacecraft to another and then superimposing their signals to determine changes in mass separations down to a few billionths of a millimeter. The spacecraft must be designed in such a way that nothing other than the geometry of spacetime itself affects the movement of the masses in free fall.
The Spanish contribution to LISA
Led by ESA, LISA is made possible through a collaboration between ESA, NASA and an international consortium of scientists, the LISA Consortium. The Spanish contribution is led by ICE-CSIC together with the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and the Universitat Politècnica de Catalunya – BarcelonaTech (UPC), through researchers who are all affiliate members of the IEEC.
The Spanish contribution focuses on the Scientific Diagnostic Subsystem (SDS), one of the three main flight subsystems. Its goal is to measure the environmental disturbances onboard each satellite in the constellation to distinguish them from the effects that gravitational waves would produce. The SDS will have temperature, magnetic field and radiation sensors on each satellite.
“To detect gravitational waves, LISA will measure the displacement between masses in free fall in each of the three satellites in space at an unprecedented level, up to the picometer level, which is approximately the size of atoms,” says Miquel Nofrarías, experimental researcher from ICE -CSIC and IEEC and member of the LISA consortium. “SDS sensors must achieve a level of precision and stability never before seen in space to be able to distinguish the effects of small environmental fluctuations from those of a gravitational wave,” he adds.
In addition to contributing to the LISA instrument, ICE-CSIC will also lead the development of a data distribution center in Spain and the algorithms necessary for its scientific use.
“The main goal is to provide the Spanish scientific community with the necessary tools to exploit the scientific potential of LISA, so that we can make revolutionary discoveries with implications for astrophysics, cosmology and fundamental physics,” says Carlos F. Sopuerta, researcher at ICE-CSIC and IEEC and member of the ESA scientific study team for the LISA mission.
The spacecraft follows in the footsteps of its predecessor, LISA Pathfinder, which demonstrated that it was possible to hold test masses in free fall with astonishing precision. The Spanish contribution to LISA Pathfinder, launched in 2015, was also led by ICE-CSIC and the IEEC within the framework of the ICE-CSIC Gravitational Astronomy Research Group.