Scientists have unveiled the coolest spaceship ever built: a two-tonne probe whose instruments will be chilled to within a tenth of a degree of absolute zero, the lowest temperature possible in nature.
The Planck spacecraft, built by the European Space Agency (ESA), will hover in space a million and a half kilometers from Earth and search the skies for faint traces of radiation left over from the universe's explosive birth 14 billion years ago.
The probe will gather these echoes of the Big Bang using instruments cooled to 273?C in order to stop any traces of heat distorting the results. The aim is to discover how matter first formed and later coalesced into stars, galaxies and, finally, living things.
The spacecraft will also search for evidence of "dark energy" and "dark matter," two mysterious entities thought to permeate the cosmos but that have so far eluded scientists. Dark energy is thought to explain why the universe is expanding more quickly than previous theories allowed for.
"The cosmos' constituent parts were created in the first minutes that followed the Big Bang," said Jan Tauber, Planck's project scientist. "This mission will let us look back to that time and find out why our universe is like it is now."
Scientists believe that almost as soon as the universe exploded into existence, tiny fluctuations appeared in its fabric. These variations later manifested themselves as matter, from which atoms, stars and galaxies later formed.
To study these fluctuations, the probe will map the skies by analyzing tiny variations in the microwave radiation left behind by the Big Bang. The key has been to ensure that Planck is kept incredibly cold in space.
"Planck will measure very tiny variations in radiation," said Andrew Jaffe, of Imperial College London. "That means we cannot afford to have spurious signals coming from its own instruments, so we have to keep them as near to absolute zero as possible."
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