New space mission will switch on the sound to study the universe in a new way

Credit: NASA, ESA, M. Livio & the Hubble Heritage Team

A new space mission that will study the universe in a completely new way will be launched by the European Space Agency in 2034.

ESA has announced today that it will create an observatory in space to detect ripples in the fabric of space–time, known as gravitational waves, which are created by celestial objects with very strong gravity.

Researchers at Imperial College London say that it will expand the way in which they can observe the universe, as though they will be able to access a sound channel where previously there was only light. Imperial has been one of the core team of ten European institutions working on this project since the mid-1990s.

Gravitational waves were predicted by Einstein’s theory of general relativity but they have never been witnessed directly before, as they do not give off light or an electromagnetic signature.

The waves are thought to be created by violent cosmic events - such as black holes merging together and the Big Bang - and by the gravitational forces of massive bodies such as stars and planets moving asymmetrically, ‘tugging’ at each other and making waves in space-time.

The current mission concept, eLISA, should open up hidden chapters in the history of the Universe by listening to the waves made by the earliest black holes, by thousands of pairs of stars, and probably by the Big Bang. By seeing how the waves from early black holes are stretched out as they move through the expanding Universe, it will also study mysterious dark energy.

Physicist Professor Tim Sumner, who leads the work on eLISA at Imperial College London, said: “This mission will enable us to study the universe in a completely new way – we’ll be ‘listening’ to it as well as looking at it. Over the centuries astronomy has grown to cover more and more of the electromagnetic spectrum, seeing more colours if you like, whether visible light, infrared, X-rays or submillimetre. With gravitational waves, we’ll have a totally different way of collecting information. It’s as though we’ve been watching a television with the sound off, and now we’re going to be able to turn the sound up and have a much clearer sense of what’s happening.

“The possibilities are mind-blowing. We’ll be able to get to grips with black holes; see how gravity works more precisely than ever before; and potentially even see what happened in the seconds after the Big Bang.”

Mission scientists will need to develop a spaceborne gravitational wave observatory, or extreme precision ‘gravitometer’, an ambitious enterprise that will push the boundaries of current technology.

The eLISA mission will situate three spacecraft halfway between the Sun and the Earth. In this position, the gravitational pull will ‘lock’ the craft in a stable position, so that the craft orbit the Sun at the same speed as the Earth. The three spacecraft will be between one and five million kilometres apart and in each one there will be a device known as a ‘proof mass’. Lasers will watch over the proof masses to detect any movement that indicates a gravitational wave passing between them.

The gravitational wave observatory is one of two missions selected by the European Space Agency today as future Large (L-class) missions. It follows on from an ESA test mission known as LISA Pathfinder, which is due to launch in 2015.

“We are very pleased with this decision. It will provide revolutionary research opportunities in astrophysics and fundamental physics,” says Karsten Danzmann, designated spokesperson of eLISA, director at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) and professor at the Leibniz Universität in Hannover, Germany. “We will immediately begin to optimise technologies already being developed for eLISA. These key technologies for eLISA will get their first test in space with the launch of ESA's LISA Pathfinder mission in 2015.”

Professor Sumner added: “The UK has been involved in this pioneering mission since the mid-1990s and my team at Imperial has been developing some of the critical hardware which will fly on the LISA Pathfinder mission.  To now have an assured launch slot for a gravitational wave observatory is testament both to the hard work put in by the whole collaboration in maturing the technology and also to the truly astounding new science which will undoubtedly come out of this mission."

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