Physicists hope the ambitious mission will allow
them to prove the existence of gravitational waves

–a phenomenon predicted in Einstein’s famous theory of general relativity and the last piece of his

theory still to be proved correct.

The mission, a collaboration between Nasa and the

European Space Agency, will use three spacecraft

flying in formation while orbiting the sun, with each

housing floating cubes of gold platinum.

Laser beams fired between the spacecraft will then

be used to measure minute changes in the

distance between each of the cubes, caused by the

weak waves of gravity that ripple out from

catastrophic events in deep space.

Einstein’s theory of general relativity predicted that

when large objects such as black holes collide,

ripples in space and time flow outwards. These

ripples are called gravitational waves.

A panel of international experts have now set out a

detailed plan for the mission and how it can be

used to reveal new insights about the universe

around us.Professor Jim Hough, an expert on gravitational

waves at Glasgow University and a member of the

committee that drew up the plans, said:

“Gravitational waves are the last piece of Einstein’s

theory of general relativity that has still to be

proved correct.

“They are produced when massive objects like

black holes or collapsed stars accelerate through

space, perhaps because they being pulled towards

another object with greater gravitational pull like a

massive black hole.

“Unfortunately we haven’t been able to detect them

yet because they are very weak. However, the new

experiments we are working on have great

potential to allow detection.”

Ground based attempts to detect gravitational

waves on Earth have so far been unsuccessful and

can only look for gravitational waves with relatively

high frequencies.

Scientists have already been able to prove a

number of predictions made by Einstein’s theory of

general relativity, including that light is bent by

gravity, that time can be warped by gravity and

that space and time can bend.

Einstein’s other theories including his most famous

formula E=mc 2 have also withstood scientific


The Laser Interferometer Space Antenna, or LISA

as the new space based mission is called, will be

able to detect gravitational waves of very low

frequencies due to the huge distance between the

three spacecraft. It will be the largest detector ever


A smaller test mission called LISA Pathfinder,

which is being built by British engineers at space

company Astrium EADS and is due to be launched

next year, is to pave the way for the more

ambitious mission by demonstrating the

technology to be used to detect the waves.

Scientists have already begun building the

instruments that will be used in LISA itself, but it is

not expected to be launched before 2020.

They hope that once detected, gravitational waves

will be able to provide new information about the

universe that cannot currently be seen using

electromagnetic radiation such as light, radio

waves and X-rays.

Professor Sheila Rowan, who also studies

gravitational waves at Glasgow University, added:

“Black holes are so dense that no light or radiation

escapes from inside them.

“Gravitational waves from the warped spacetime

around black holes could give us new ways of

looking at them.

“We could also learn about the state of matter

inside collapsed stars.”

Dr Ralph Cordey, science and exploration business

development manager at Astrium UK who are

building LISA Pathfinder, said: “Trying to measure

cosmic events such as collapsing star systems or

the collision of massive black holes throughout our

universe requires ultra-high precision technology.

“The ultimate goal is to prove that this technology

works, before we attempt to put three spacecraft

into orbits at a distance of 5 million kilometres

from one another, connected only by a laser beam

that will measure their positions accurate to 40

millionths of a millionth of a metre.”