Laser interferometry: Measuring up to see if Einstein was right
The ‘optical bench’ will form part of the European Space Agency’s LISA Pathfinder space mission which will blast off on Wednesday December 2, 2015 from the Guiana Space Centre in Kourou, French Guiana.
The existence of the ripples, known as gravitational waves, was predicted by Einstein’s Theory of General Relativity.
The ESA partners believe that the best way to detect the faint ripples from the biggest and most distant of astronomical sources is to place three satellites, separated by millions of kilometres, in the vacuum of space, where they will be free of the Earth’s vibrational interference.
In LISA, each of these satellites will contain one or two freely floating ‘test masses’. Sensitive measurements of the relative positions of the masses at the end of each long arm of the triangular arrangement of satellites will then reveal the gravitational waves.
The LISA Pathfinder mission compresses one arm of LISA into a single compact spacecraft to allow testing of the critical technology items in preparation for LISA. Pathfinder contains two test masses – floating gold/platinum cubes – that, ideally, will move completely free of any disturbances. A sensitive laser interferometer will monitor the separation between them with precision looking for tell-tale movements caused by any tiny stray forces.
The laser interferometer was developed, built and tested over the last 10 years by researchers from the University’s Institute for Gravitational Research. The device is capable of detecting changes in distance between the test masses as small as 10 picometres, or one hundred millionth of a millimetre.
Dr Harry Ward, who leads the University’s LISA Pathfinder team, said: “We’ve been involved in gravitational wave research for the better part of a half-century now, and we’ve already made important contributions to Earthbound detectors such as LIGO in the US and GEO600 in Germany.
“For the last decade, we’ve been working very hard on LISA Pathfinder, which is a tremendously exciting project involving researchers from all over Europe," explained Ward. “The launch of the LISA Pathfinder is a major milestone, not just for us and the European Space Agency’s other partners, but for developing further our understanding of the Universe.
“Although this mission won’t be looking directly for evidence of gravitational waves, it is a vitally important step towards the ESA’s eLISA project, which will place two detectors in space some millions of kilometres apart and will allow us a research opportunity which is totally unprecedented in the history of astronomy".
The spacecraft will set off from Earth atop a Vega rocket, an expendable launch system developed by the Italian Space Agency and the European Space Agency.
Following a series of six orbit-raising manoeuvres within two weeks of launch, the spacecraft will journey for six weeks to its operating orbit around the Sun–Earth L1 Lagrange point, some 1.5 million km from Earth towards the Sun. The L1 point is a point in space where the spacecraft can stay approximately lined up between the Earth and the Sun as the Earth follows its annual orbit.
LISA Pathfinder is a European Space Agency project, with contributions from 14 different European countries and from the USA. The spacecraft has been developed and built in Stevenage by Airbus Defence and Space. The UK payload items have been funded by the UK Space Agency with major contributions coming from Glasgow University, Imperial College, Birmingham University and the Mullard Space Science Laboratory.
Related articles and links:
News articles:
Can more precise monitoring reduce solar flare threat?
Leap seconds are with us until 2023 (at least)
If you enjoyed this article, you will like the following ones: don't miss them by subscribing to :
