LISA: the space mission that will revolutionize astrophysics

Astrophysics is about to enter a new era thanks to LISA (Laser Interferometer Space Antenna), a joint ESA-NASA mission that promises to revolutionize our understanding of the Universe. This pioneering space mission is designed to detect gravitational waves that escape terrestrial instruments, opening new frontiers in cosmic exploration. It is part of the research conducted by Professor Daniele Bortoluzzi from the Department of Industrial Engineering.

Gravitational waves, predicted by Einstein in his general theory of relativity, are disturbances in spacetime generated by cataclysmic cosmic events such as the merger of black holes and neutron stars. Until a few years ago, these phenomena were unreachable by science. However, with the advent of terrestrial observatories like LIGO and VIRGO, we began to perceive these cosmic “ripples.” Now, LISA promises to extend this observational capability beyond the limits of ground-based instruments.

LISA will consist of three satellites positioned in an orbit around the Sun, each hosting two free-falling reference masses. These satellites will be spaced 2 million kilometers apart. When a gravitational wave passes through the area between the satellites, it causes tiny variations in the distance between the reference masses, which will be measured with extreme precision using laser beams.
The technological core of the mission lies in the six Gravitational Reference Sensors (GRS), which contain the reference masses and minimize disturbances to their trajectory. These sensors were successfully tested during ESA’s LISA Pathfinder technology demonstration mission (2015-2017). LISA Pathfinder was developed with scientific and technological contributions from the University of Trento (Department of Physics, Department of Industrial Engineering) and TIFPA, funded by ASI, with OHB Italia as the industrial partner.

The realization of LISA involves significant engineering challenges. One of the most complex aspects concerns the release mechanism of the test masses. During satellite launch, the masses are locked in place to prevent damage. Once in orbit, they must be released in such a way that they follow a pure geodesic trajectory, influenced only by planetary gravity. This requires an extremely precise and reliable mechanism capable of releasing the masses with minimal residual velocity. A non-compliant release phase would prevent the initialization of the scientific phase, which is the mission’s primary objective.

The Department of Industrial Engineering (DII) at the University of Trento played a crucial role in this phase, developing tools and experiments to simulate the functioning of the mechanism under representative space conditions. This research activity includes studying surface adhesion, measuring impulses, characterizing the dynamic response of mechanisms, developing digital twin models, and more. During the LISA Pathfinder mission, the team contributed to designing and conducting in-flight experiments with the mechanism to test its actual functionality and performance.

The Future of LISA

The LISA mission recently passed a critical review and has received official adoption by ESA. The launch is scheduled for around 2035, and the research team (Giuliano Agostini, Abraham Ayele Gelan, Edoardo Dalla Ricca, Francesco Marzari, Matteo Tomasi, Davide Vignotto, Carlo Zanoni) is currently engaged in the design and development phase of the mission’s dedicated mechanisms. This ambitious project will not only allow us to observe cosmic events with unprecedented precision but could also provide new insights into galaxy formation, stellar evolution, and the first moments after the Big Bang.

In summary, LISA represents a fundamental step in our understanding of the Universe. International collaboration, technological innovation, and scientific dedication are converging to open a new window into the cosmos, bringing us closer than ever to deciphering the mysteries of our Universe.