The European Space Agency (ESA) is preparing to launch a groundbreaking mission known as the Laser Interferometer Space Antenna (LISA). This mission aims to detect and study gravitational waves from space, marking a significant advancement in our ability to observe these ripples in spacetime predicted by Albert Einstein over a century ago.
LISA will be the first space-based gravitational wave observatory. Selected to be ESA’s third large-class mission, it will address the science theme of the Gravitational Universe.
LISA is not a single spacecraft but a constellation of three spacecraft that will trail Earth in its orbit around the Sun. These spacecraft will form an equilateral triangle with sides measuring 2.5 million kilometers, more than six times the distance between the Earth and the Moon.
They will exchange laser beams over these vast distances with unprecedented precision, following Earth in its orbit around the Sun. Launch is expected in 2037.
The mission will be launched aboard an Ariane 6 rocket, marking the beginning of an ambitious project that has never been attempted before. The use of laser beams to measure distances between spacecraft over millions of kilometers represents a monumental leap in technology, enabling the detection of gravitational waves from events involving massive cosmic objects.
“LISA is an endeavor that has never been tried before,” explains Nora Lützgendorf, the lead project scientist for LISA. “Using laser beams over distances of several kilometers, ground-based instrumentation can detect gravitational waves coming from events involving star-sized objects – such as supernova explosions or merging of hyper-dense stars and stellar-mass black holes. To expand the frontier of gravitational studies, we must go to space.”
Gravitational waves are minuscule ripples in the fabric of spacetime caused by the acceleration of massive objects, such as merging black holes or neutron stars. These waves were first predicted by Einstein’s theory of general relativity in 1915 and were directly detected for the first time by the ground-based Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2015. However, LIGO’s sensitivity is limited to higher frequency waves produced by smaller-scale events.
LISA’s configuration, with its vast inter-spacecraft distances, will allow it to probe lower frequency gravitational waves that cannot be detected from Earth. This capability will enable scientists to uncover a different scale of cosmic events, potentially revealing information about the early universe and the formation of large-scale structures.
“Thanks to the huge distance travelled by the laser signals on LISA, and the superb stability of its instrumentation, we will probe gravitational waves of lower frequencies than is possible on Earth, uncovering events of a different scale, all the way back to the dawn of time,” Lützgendorf adds.
“In 2015, the ground-based LIGO observatory cracked open the window into gravitational waves, disturbances that sweep across space-time, the fabric of our universe,” said Mark Clampin, director of the Astrophysics Division at NASA. “LISA will give us a panoramic view, allowing us to observe a broad range of sources both within our galaxy and far, far beyond it. We’re proud to be part of this international effort to open new avenues to explore the secrets of the universe.”
The success of the LISA mission promises to expand our understanding of the universe, providing new insights into cosmic phenomena and the fundamental nature of gravity.
As the launch date approaches, the scientific community eagerly anticipates the wealth of data and discoveries that LISA will bring.