Final results from LISA Pathfinder satellite

The final results from the ESA satellite LISA Pathfinder (LPF) have been published today. Using data taken before the end of the mission in July 2017, the LPF team – including researchers from the Max Planck Institute for Gravitational Physics in Hannover and Leibniz Universität Hannover – significantly improved first results published in mid 2016. LPF now has exceeded the requirements for key technologies for LISA, the future gravitational-wave observatory in space, by more than a factor of two over the entire observation band. LISA is scheduled to launch into space in 2034 as an ESA mission and will "listen" to low-frequency gravitational waves from merging supermassive black holes in the entire Universe and tens of thousands of binary stars in our galaxy.

"LISA Pathfinder beautifully demonstrated the key technologies for LISA, the future gravitational-wave observatory in space: the perfect undisturbed free fall of two cubic test masses inside the spacecraft," says Prof. Karsten Danzmann, director at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI) and director of the Institute for Gravitational Physics at Leibniz Universität Hannover, who also is the Co-Principal Investigator of the LISA Technology Package. "We were blown away by the results in the first weeks of the mission, but our final results using more and better data and a deeper understanding of our space laboratory LPF really are a sight to behold."

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Credit: ESA

Analysis of the LISA Pathfinder mission results towards the end of the mission (red line) compared with the first results published shortly after the spacecraft began science operations (blue line). The initial requirements (top, wedge-shaped area) and that of the future gravitational-wave observatory LISA (middle, striped area) are included for comparison, and show that LISA Pathfinder far exceeded expectations.

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Credit: AEI/MM/exozet; GW simulation: NASA/C. Henze

The proposed LISA mission will detect gravitational waves in space using a trio of satellites, separated by millions of kilometers. Lasers will be employed to measure the minute changes in their relative distance induced by impinging gravitational waves.

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Launched in December 2015, LISA Pathfinder travelled to its operational orbit, 1.5 million km from earth towards the Sun, where it started its scientific mission on 1 March.

At the core of the spacecraft, two identical gold-platinum cubes, are being held in the most precise free-fall ever produced in space.

Placing the test masses in a motion subject only to gravity is the challenging condition needed to build and operate a future space mission to observe gravitational waves. Predicted by Albert Einstein a century ago, gravitational waves are fluctuations in the fabric of space-time, which were recently detected directly for the first time by the Laser Interferometer Gravitational-Wave Observatory.

Over the first two months of scientific operations, the LISA Pathfinder team has performed a number of experiments on the test masses to prove the feasibility of gravitational wave observation from space.

 

Gravitational wave observations will enable studies of: the formation and growth of massive black holes and their co-evolving host galaxies; structure formation; stellar populations and dynamics in galactic nuclei; compact stars; the structure of our Galaxy; General Relativity in extreme conditions; cosmology; and searches for new physics. Information from LISA sources will provide unique insight into extraordinary astrophysical objects. Combined with electromagnetic observations, these insights will advance the broader scientific understanding.