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Artist's
conception of LISA superimposed on ripples in space-time powered
by the collision of supermassive black holes. The individual
3-meter-diameter spacecraft are separated by 5 million kilometers
and trail Earth in its orbit.
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Gravitational
radiation consists of ripples in space with long wavelengths, which
grow longer roughly in proportion to the amount of mass in violent
motion that produces these ripples. Earthbound detectors can find
gravitational radiation from individual stars as they collapse or
coalesce, but detection of the longest-wavelength gravitational
radiation requires a supersensitive detector located in space. The
Laser Interferometer Space Antenna (LISA), a joint venture of the
United States and the European Space Agency, will deploy a system
of reflecting antennas, spaced at distances of millions of kilometers,
that reflect laser beams back and forth between them.
These
beams will not only measure the distances between the reflectors
but also detect any tiny changes in these distances (less than one-hundredth
the diameter of a single atom) that arise from the passage of waves
of gravitational radiation. This capability will allow LISA to measure
gravitational radiation at lower frequencies than an earthbound
detector can access. LISA will also be able to detect the gravitational
radiation from the coalescence of supermassive black holes.
Visit
the Official LISA Site
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