On the 27th of October this year at the Royal Society in London, the University of Glasgow’s own LISA Pathfinder team was awarded the 2016 Sir Arthur Clarke Award. Sponsored by the UK Space Agency, the Sir Arthur Clarke awards have been acknowledging and rewarding outstanding achievements made in British space activities each year since 2005. This year’s “Space Achievement in Academic Research or Study” award was given to Dr. Harry Ward and his five person team for their involvement on the LISA (Laser Interferometer Space Antenna) Pathfinder. They developed an Optical Bench Interferometer for the ESA spacecraft, and its purpose is to test the practicality of gravitational wave observation in space.
Gravitational waves are a form of radiation that is given off when massive objects are interacting gravitationally. They were predicted by Einstein’s theory of General Relativity, and are normally too weak to be detectable. However, during violent astronomical events such as black hole mergers, the waves are emitted with sufficient intensity and may become detectable by ultra-sensitive instruments. The groundbreaking first detection of gravitational waves (made possible in part by the research done at the University of Glasgow’s Institute for Gravitational Research) was done on 14 September 2015. Following this exciting detection, there has been increased interest in creating even more precise and efficient gravitational wave detectors.
A necessary technology for gravitational wave research is the interferometer, an instrument that bounces lasers off mirrors in a configuration that allows for very precise measurements of the distance between two free-floating heavy masses with reflective surfaces. Interferometers are used in detecting gravitational waves because they are able to measure very small deviations in distance. When a gravitational wave passes by, it stretches and contracts the space it moves through, thereby moving the targets of the lasers. This extremely tiny change in distance gives a different measurement from the original, unperturbed system and indicates the presence of a gravitational wave.
The LISA Pathfinder has been created as a precursor to ESA’s flagship gravitational wave observatory, eLISA, that will hopefully be launched in the early 2030’s. eLISA (Evolved Laser Interferometer Space Antenna) will be a large-scale array of three spacecrafts designed to detect gravitational waves. This array will form a massive triangle configuration orbiting the Sun: it will create an extremely large interferometer, much larger than any interferometer that can be built on Earth. eLISA can be thought of as a huge Michelson Interferometer, with each arm stretching 1 million kilometres! This will allow the measurement of gravitational waves to take place over a broad band of low frequencies (0.1mHz to 1Hz). This is a much richer range than is possible on Earth at observatories such as LIGO (Laser Interferometer Gravitational Wave Observatory), due to terrestrial gravity gradient noise and arm-length limitations.
In order to make eLISA happen, LISA Pathfinder has been created to test how certain technologies necessary to gravitational research hold up in space. The Optical Bench Interferometer realised by the team in the School of Physics and Astronomy helps test the practicality of flying a gravitational wave observatory in space, and carrying out experiments in these conditions. Unperturbed by any external forces, being in space creates an extremely quiet environment to conduct these measurements, allowing scientists to measure the effects of gravity with great accuracy.
So far, the first results indicate LISA Pathfinder has been working to a precision five times better than required. This is great news and helps give a green light for the eLISA mission to progress. The success of LISA Pathfinder is due to many people’s research, but notably, the work done here at the University of Glasgow in the Institute for Gravitational Research.
Bibliography:
More information on the Sir Arthur Clarke Awards: http://www.bis-space.com/2016/10/24/17965/the-sir-arthur-clarke-awards-2016
More information on Dr. Harry Ward and his team at the University of Glasgow:
http://www.physics.gla.ac.uk/igr/index.php?L1=research&L2=lisa
More information on LISA Pathfinder and eLISA:
https://www.elisascience.org/