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Test masses floating freely inside LISA Pathfinder

Test masses floating freely inside LISA Pathfinder

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Major milestone reached on the path to science mission in March

LISA Pathfinder is a test mission that seeks to test the key technologies required to measure gravitational waves in space - such as the perfect free fall of two test masses. A milestone on the path to the science mission, set to begin on 1 March 2016, has now been reached. LISA Pathfinder has, for the first time, released the test masses - two identical 46 mm gold-platinum cubes - from their locking fingers. The cubes are now floating freely inside the satellite. A laser system, developed under the leadership and with the significant participation of researchers from Hannover and Leibniz Universität Hannover, measures the distance between the masses with unprecedented levels of accuracy.

"LISA Pathfinder is still working perfectly! Releasing the test masses required some learning, but the team soon came up with an elegant solution. By successfully operating a laser interferometer in space between two freely floating test masses, LISA Pathfinder has created a genuine world novelty," stated Professor Karsten Danzmann, Head of the Institute of Gravitational Physics at Leibniz Universität Hannover and Director of the Max Planck Institute for Gravitational Physics. "We will shortly begin our science mission, which will demonstrate key technologies for observing gravitational waves in space."

Precise measurements using laser interferometry

A laser interferometer is located between the two test masses, which sit some 38 centimetres apart. This device measures the positions and direction of the two test masses relative to the satellite and to each other with unprecedented accuracy of around ten picometres (one picometre equates to a billionth of a millimetre). The aim is to measure perfect free fall. This optical precision measurement system was developed and constructed under the leadership and with the significant participation of researchers from the Max Planck Institute for Gravitation Physics and Leibniz Universität Hannover.

Data analysis in Hannover

After a week of final tests, LISA Pathfinder's science mission will begin on 1 March 2016. The mission involves demonstrating and validating key technologies for proving gravitational waves in space, paving the way for future gravitational wave observatories in space, such as eLISA.

Researchers from the Max Planck Society and Leibniz Universität Hannover play a leading role in developing the evaluation software, which is material to extracting the crucial information from the measured data. To achieve this, the institute operates a control room in Hannover. Since the immediate evaluation of the data is essential for configuring follow-up tests, researchers from the institute also work round-the-clock shifts at the European Space Operations Centre (ESOC) of the European Space Agency ESA in Darmstadt.

LISA Pathfinder is an ESA mission. Airbus DS undertakes responsibility for the system of the mission, involving European aerospace companies, research institutions from France, Germany, Italy, the Netherlands, Spain, Switzerland and Great Britain, and NASA.

LISA Pathfinder is funded by the Federal Ministry for Economic Affairs and Energy via the German Aerospace Center (DLR) based on a resolution passed by the German Bundestag.