The search for gravitational waves continues: In a few days, the spacecraft LISA Pathfinder launches, is designed to test the key technologies for the detection of the elusive waves. The systems of the probe can measure distances to a millionth of the thickness of a hair accurately and shield their experiments against all external disturbances. Manages this test, this is an important step towards a space observatory for gravitational waves.
The spacecraft LISA Pathfinder (artist’s impression) serves as a test of important technologies for the direct detection of gravitational waves.
© ESA / ATG medialab 
Gravitational waves are something like a holy grail of astrophysics: Einstein’s General Theory of Relativity predicts that it must exist, but no one has seen them. Huge cosmic events Wiever melting black holes or star explosions leave According to the theory suggest spacetime wave, like a thrown pebble into a pond sends waves on the water surface. Such gravitational waves are so far only indirectly detectable. To detectors on Earth, comparing the durations of laser pulses for hundreds of meters with each other and measure such small deformations of space-time directly, so far been unsuccessful.
tiny distortions of spacetime
Since the gravity and Earth’s magnetic field complicate the direct detection of gravitational waves, is now helping Pathfinder in space while the ESA spacecraft LISA. With the technology on board the spacecraft, scientists want to find out whether such proof has ever technically feasible first: “These tiny distortions of spacetime require a very sensitive and high-precision measuring technology, their performance can only be tested in space free from external interference,” says François Auque of the developer company Airbus Defence and Space.
The LISA technology package consists of a laser interferometer and two precisely constructed, 1.96 kilogram cubes from a gold-platinum alloy. The cubes serve as test masses, while the interferometer measures the distance between them in unprecedented detail. The device will detect differences in the picometer, which is less than one-millionth the thickness of a human hair.
The special feature here is that the two dice are float freely at a distance of about 40 centimeters during the experiment as soon as they are freed from their holders. Free from any confounding factors, they are then in free fall, which is exclusively influenced by gravity.
Completely new look at the universe
To this end, the scientists also test two different microdrives on board the spacecraft. Each of these engines is so weak that it could prevent a snowflake on sinking down just. LISA Pathfinder is to counteract these drives, for example, the solar radiation and compensate for disturbing movements from the outside, so that the movement of the test cube remains unaltered.
Background of LISA Pathfinder Mission
© ESA
If all this technology works flawlessly, paves LISA Pathfinder possibly the way to new research methods: Existing telescopes use almost exclusively electromagnetic waves of different wavelengths, from radio waves to X-rays. A space observatory that uses gravitational waves, could therefore provide a whole new view of the universe. The plan is to an ensemble of three space probes that form a huge triangle and determine their positions to each other in the smallest detail with lasers.
Spacecraft start for early risers
The start of the nearly two-ton probe from ESA spaceport in Kourou, French Guiana is scheduled for December 2, 2015 at 5:15 Central European Time Clock. After several correction maneuvers LISA Pathfinder will reach towards the end of January 2016 at their destination, the first Lagrange point between the Earth and sun. The scientific experiments are performed at a distance 500000-800000 kilometers held in orbit around this point
Interested Early risers can watch the launch live. The ESA will set up a live stream and the start about the Twitter accountsesaoperations,ESA_LPF and ESA comment under the hashtag #LISAPathfinder.
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