NASA's astronauts blasted off just yesterday on a final repair mission to the Hubble Space Telescope, but two space-based telescopes scheduled to rocket into space tomorrow may soon steal the spotlight from the Hubble. The two European Space Agency observatories, named Herschel and Planck, may revolutionize our understanding of how galaxies formed in the young universe, shortly after the Big Bang. Once the telescopes are in place, says ESA science director David Southwood,
the next era of space-based astronomy will then be well and truly upon us. "They are at a pivotal point," he says. "From now on astronomy is going to be done from deep space" [Nature News].
Both telescopes will be carried into space by the same Ariane 5 rocket, which is expected to launch tomorrow from a spaceport in French Guiana.
The destination for both telescopes is a remarkable position in space known as the second Lagrangian point (L2). It is one of five gravitational "sweet-spots" around the Sun-Earth system where satellites can maintain station by making relatively few orbital corrections. L2 is some 1.5 million km from Earth on its "night side". The observatories will circle this point [BBC News]
, orbiting at different distances to rule out any chance of a collision. At that stable location, the telescopes will be protected from temperature swings; a crucial point since both telescopes must be kept at frigid temperatures to study the "cold universe."
Herschel, named for British astronomer William Herschel, the discoverer of Uranus, will sweep the entire sky every six months over a three-year period. It will build the most accurate map ever made of the cosmos. Because light from very old and distant objects is stretched out toward the red end of the electromagnetic spectrum, Herschel's infrared vision will let it see stars and galaxies as they were forming billions of years ago [Miami Herald].
Herschel will peer into the cold clouds of interstellar dust and gas that gradually gave rise to "protostars," star precursors that emit infrared radiation. The telescope will be kept at 0.3 degrees kelvin with a huge sun shield and supercooled helium so that it can detect the tiny rise in heat as the radiation comes in. The Planck spacecraft, named after famed German physicist Max Planck,
has been described as the "coolest spaceship ever built". Its instruments will be chilled to within a tenth of a degree of absolute zero, the lowest temperature possible in nature. It will then hover in space a million miles from Earth, searching the skies for faint traces of radiation left over from the universe's explosive big bang birth 14 billion years ago. The aim is to discover how matter first formed and later coalesced into stars, galaxies and, finally, living things [The Guardian].
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