Categories: European Space Agency Gravity

ESA Launches Probe To Measure Gravitational Waves Theorized By Einstein

A Vega rocket carrying ESA’s LISA Pathfinder successfully launched from Kourou, French Guiana.
Credit: ESA

KOROU, French Guiana – A European Space Agency spacecraft designed to observe gravitational waves from space lifted off early Sunday morning on a Vega rocket from Europe’s spaceport in Kourou, French Guiana.

Gravitational waves are ripples in the fabric of spacetime, predicted one hundred years ago by Albert Einstein’s General Theory of Relativity. Einstein’s theory predicts that these fluctuations should be universal, generated by accelerating massive objects. However, they have not been directly detected to date because they are so tiny.

ESA’s LISA Pathfinder will us a pair of identical 46 mm gold-platinum cubes separated by 38 cm, which will be isolated from all external and internal forces acting on them, except gravity. If all goes as planned, the mission will put these cubes in the purest free-fall ever produced in space and monitor their relative positions to astonishing precision, laying the foundations for gravitational wave observatories in space.

The probe is expected to reach its operational orbit located nearly a million miles away from Earth in about 10 weeks after launch (mid-February). After final checks, it will begin its six-month scientific mission at the beginning of March.

While en route to the final orbit, the two cubes will be released from the locking mechanisms that hold them during launch and cruise. Once in orbit around a stable virtual point in space, the final mechanisms will be unlocked and the cubes will no longer be in mechanical contact with the spacecraft.

A complex system of laser beams bouncing between the two cubes will then measure how close to true free-fall they are to within a billionth of a millimeter – a measured observation never previously achieved in space.

“Fundamental research tries to understand our world,” says Johann-Dietrich Woerner, ESA’s Director General. “Einstein’ s theoretical findings are still very impressive. With LISA Pathfinder we will try to take a further step towards confirmation of one of Einstein’s predictions: gravitational waves. “
This artist’s impression illustrates the LISA Technology Package core assembly. The two gold cubes, enclosed in vacuum containers (shown here with the launch lock mechanism), are key to the LISA Pathfinder mission. Each of these electrode containers houses a gold-platinum test mass. LISA Pathfinder will monitor the two cubes as they enter free-fall motion using a high-precision laser interferometer.

The optical bench interferometer is shown between the two masses. This instrument is made from a 20 cm by 20 cm block of Zerodur ceramic glass, and has a set of 22 mirrors and beam-splitters bonded to its surface that direct laser beams. These beams will allow scientists to precisely measure the cubes’ motion, position, and orientation without touching them. In this way, LISA Pathfinder will perform the first high-precision laser interferometric tracking of orbiting bodies in space. Credit: ESA

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