LISA, short for Laser Interferometer Space Antenna, will be the first space-based mission dedicated to observing gravitational waves ripples in space-time first predicted by Albert Einstein. The mission will allow scientists to explore parts of the universe that cannot be studied using ground-based observatories.
Under the Phase B2 contract, Thales Alenia Space UK will be responsible for the design, manufacture, assembly, integration and testing of the propulsion subsystem. The work is expected to progress into Phases C and D, bringing the total contract value to €89.5 million.
Gravitational waves are generated by some of the most extreme events in the universe, including merging supermassive black holes and interacting compact stars. LISA’s unprecedented sensitivity will enable scientists to observe these phenomena across a frequency range inaccessible from Earth, extending our view of the cosmos back to the earliest epochs before stars and galaxies formed.
To achieve this, the spacecraft must be engineered so that no forces other than the curvature of space-time itself influence the motion of the onboard test masses. These masses must remain in near-perfect free fall along the measurement axes, a demanding technical challenge at the heart of the mission.
LISA will consist of three spacecraft flying in a triangular formation, separated by 2.5 million kilometres and trailing or leading Earth in its orbit around the sun. Each satellite will carry two reference masses, with laser beams exchanged between the spacecraft to measure minute changes in distance with a precision smaller than the diameter of an atom. The constellation is scheduled to launch in 2035 aboard an Ariane 6 rocket.
In addition to the propulsion subsystem, Thales Alenia Space will supply several mission-critical systems to OHB, including spacecraft avionics and control software, telecommunications, and the drag-free and attitude control system (DFACS).
The DFACS is a core element of the LISA mission. It will manage “constellation acquisition”, establishing and maintaining the laser links between the three spacecraft while also compensating for non-gravitational forces such as solar radiation pressure. This ensures the test masses follow a purely geodesic path, unaffected by external disturbances.
Thales Alenia Space is also responsible for maintaining the mission’s exceptionally demanding electromagnetic, radiation and self-gravity environments, managing the associated performance budgets to ensure the payload can operate as required.
Richard Thorburn, chief executive officer of Thales Alenia Space UK, said the company was proud to contribute to the mission.
“We are delighted that OHB System AG has selected Thales Alenia Space in the UK to bring our advanced capabilities and propulsion expertise to this remarkable scientific endeavour,” he said.
Leonardo, which holds a 33 per cent stake in Thales Alenia Space, is also contributing key technologies to the mission, including highly precise micro-propulsion assemblies used to control spacecraft attitude with extreme accuracy.
Across Europe, multiple Thales Alenia Space sites will support the LISA program. The company’s Turin team, as part of the LISA Core Team, is drawing on experience from a five-year study phase led by Thales Alenia Space as prime contractor.
In Gorgonzola, Italy, the on-board computer and mass memory will be developed as an integrated unit, while the Swiss operation will contribute to instrument electronics and the constellation acquisition system. Other sites will supply additional subsystems and equipment.
The mission builds on the success of LISA Pathfinder, which demonstrated the ability to keep test masses in free fall with extraordinary precision. The same class of high-accuracy propulsion system previously used on ESA’s Gaia and Euclid missions will ensure each LISA spacecraft can maintain laser alignment across the vast 2.5 million kilometre distances involved.
“We look forward to working closely with all partners on the program to support ESA’s ambition to deepen our understanding of the universe,” Thorburn said.