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
“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
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.”