Detecting gravitational waves
Name LISA, the Laser Interferometer Space Antenna
Scope LISA is designed to search for and detect gravitational radiation from astronomical sources. In doing so, it will unveil the history of galaxies and black holes in the universe and the physics of dense matter and stellar remnants. LISA will also test some of the fundamental tenets of the theory of gravitation.
Description LISA is a cooperative mission between ESA and NASA.
It is designed to detect 'ripples' in the fabric of space-time created during highly energetic events in which very massive objects undergo strong acceleration. The ripples created are called gravitational waves. This effect was predicted by Einstein's general theory of relativity. Examples of events that cause them are massive black holes swallowing neutron stars or collisions between massive black holes. LISA will be the first mission to detect gravitational waves in space.
The measurements To achieve the goal, three spacecraft form an equilateral triangle with arm’s length of about 5 million km. Each spacecraft is kept centred around two cubes made of a gold-platinum alloy. The cubes float freely in space and the spacecraft protects them from the hazards of interplanetary space. The distance between the cubes in different spacecraft is monitored using highly accurate laser-based techniques. In this manner, it is possible to detect minute changes caused by a passing gravitational waves.
Launch Scheduled for 2018, the mission is currently planned to launch from NASA’s Kennedy Space Centre in the USA on board an Atlas 531 rocket.
Status Under assessment
The current phase was started in January 2005 with a 24-month industrial contract assigned to Astrium GmbH. System engineering activities performed on the mission architecture and design allowed finalisation of the baseline mission design in October 2005 at the Mission Architecture Review. The study has been extended to July 2008 in order to analyse new architectural options in detail.
Journey As per plan the three spacecraft will be launched together. They will independently reach their final orbits around the Sun using their chemical propulsion system. The constellation of spacecraft will orbit the Sun, trailing Earth by 50 million km.
Configuration Unlike the standard configuration of a spacecraft carrying a payload of instruments, LISA’s spacecraft and payload will be closely interconnected,in what can be called a ‘science-craft’. Each science-craft will carry two free-flying proof masses with associated sensors, two identical telescopes, and two optical benches with interferometry measurement systems to measure the relative displacement of each pair of proof masses on different spacecraft.
The advanced technology for LISA will be flight-tested first by the LISA Pathfinder mission.