Spacecraft

LISA will consist of three identical spacecraft built by OHB-System AG. Flying in a giant triangular formation 2.5 million kilometres apart, they will trail Earth in its orbit around the Sun. Each spacecraft carries ultra-stable lasers, precision optics, and free-floating gold-platinum test masses, enabling them to measure minuscule changes in distance caused by passing gravitational waves. Their identical design ensures seamless operation as a single, space-based observatory.

Credit: OHB | Fullsize Image
Credit: OHB | Fullsize Image
Credit: OBH | Fullsize Image

 


 

Payload

LISA’s payload is a collaborative effort between ESA, its member states, and NASA. The main components are the Gravitational Reference System (GRS), the Interferometric Detection System (IDS), the Lasers, the Telescopes, and the Science Diagnostic System (SDS).


Gravitational Reference System (GRS)

Developed in Italy with contributions from Switzerland and the United States, the GRS is the heart of LISA. It houses the free-falling, gold-platinum test masses that serve as the mission’s fundamental reference points for detecting gravitational waves.

 

Interferometric Detection System (IDS)

Led by Germany with contributions from the Netherlands, Belgium, the United Kingdom, France, and the Czech Republic, the IDS includes all hardware required for the precision interferometric measurements. Key elements include the optical bench, phasemeter, and quadrant photodiodes, which together track minute changes in the distance between the test masses.

 

Lasers

Provided by NASA, the laser system generates the highly stable light used in the interferometric measurements, enabling the detection of the incredibly small distortions in space caused by passing gravitational waves.

Credit: NASA | Fullsize Image


 

Telescopes

Also supplied by NASA, the telescopes transmit and receive the laser beams between spacecraft over distances of 2.5 million kilometers, maintaining the link needed for LISA’s measurements.

Credit: NASA | Fullsize Image


 

Science Diagnostic System (SDS)

Built in Spain, the SDS monitors environmental conditions that could influence LISA’s measurements. It includes sensors for temperature, magnetic fields, radiation, and electrical charge distributed across the spacecraft, allowing scientists to identify and correct for non-gravitational noise in the data.

Ground Segment

The LISA ground segment consists of the Mission Operations Ground Segment—comprising the Mission Operations Centre (MOC), ground stations, and the Science Operations Centre (SOC)—and the Science Ground Segment (SGS), which also includes the Distributed Data Processing Centre (DDPC) from ESA Member States and NASA’s Science Ground Segment (NSGS). Located at ESA’s European Space Astronomy Centre (ESAC) in Madrid, the SOC is the link between MOC and the rest of the SGS. It prepares payload commands, receives and processes raw telemetry from the spacecraft, manages calibration, stores and distributes all data products, and operates pipelines for near-real-time processing and transient alerts. In coordination with the DDPC and NSGS, the SOC supports all stages of LISA data processing and oversees public data releases.

 

Credit: ESA | Fullsize Image