The completed LISA Pathfinder spacecraft
On Wednesday December 2, the University of Glasgow will see its highly sensitive 'optical bench' launched into space as the first part of a European Space Agency project to study ripples in the curvature of spacetime.
The LISA Pathfinder spacecraft will blast off from the Guiana Space Centre in Kourou, French Guiana atop a Vega rocket. It forms the first stage of an ambitious European Space Agency (ESA) research project, 'LISA', which will study the ripples in the curvature of spacetime caused by extreme astronomical events such as the merging of super-massive black holes. The existence of these ripples, known as gravitational waves, was predicted by Einstein’s Theory of General Relativity.
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. It’s exhilarating and a little bit frightening that we’re finally on the verge of seeing it set off on the mission it was conceived to undertake and I’ll be lucky enough to see it from the launch site in Kourou.”
To detect the extremely faint ripples from some of the biggest and most distant astronomical sources the ESA 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.
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 will move completely free of any disturbances.
A very sensitive system called a laser interferometer, developed by the University of Glasgow's Institute for Gravitational Research, will monitor the separation between them with “exquisite precision” looking for tell-tale movements caused by any tiny stray forces. The laser interferometer is capable of detecting changes in distance between the test masses as small as 10 picometres, or one hundred millionth of a millimetre. The device will be used
Ward said: “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’s a vitally important step towards the ESA’s LISA 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.
“It’s an exciting time to be working in this field and we’re looking forward to the next stage of the exploration of the gravitational Universe.”
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.