Galileo satellites prove Einstein's relativity theory to highest accuracy yet
publication can be found here: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.231102
Due to a malfunction of the Soyuz upper stage, two Galileo satellites did not reach their intended altitude in August 2014. Researchers at the Center of Applied Space Technology and Microgravity (ZARM) at the University of Bremen immediately saw this as a possible stroke of luck for their research into Einstein's theory of relativity. The results of this unexpected scientific satellite mission have now been published in the renowned journal “Physical Review Letters”.
On 22 August 2014 the two satellites Galileo 5 and 6 were launched with a Russian Soyuz capsule. Due to a malfunction in the upper stage of the rocket the satellites were unable to reach their planned circular orbit at an altitude of 23,500 kilometers. Instead they are flying on an elliptical orbit, changing their altitude twice a day by about 8,700 kilometers. Since at first it looked as if the satellites could not be used for the Galileo positioning system, it was even considered shutting them down completely.
New use of the satellites
Instead, gravitational physicists at ZARM proposed to use the satellites, along with their preinstalled atomic clocks, for an improved test of the gravitational red shift. This effect is one of the central predictions of Albert Einstein’s General Law of Relativity. It states that gravitation – in this case Earth’s gravity – influences time. To be more precise: clocks that are far away from Earth run faster than identical clocks located on the surface of the Earth.
In cooperation with partners at the TU Munich the ZARM team was able to confirm the gravitational red shift four times more accurately than before with this result being the first improvement to this test of the theory of relativity in more than 40 years. A parallel analysis of a French team came to a similar result. Both results were now published in the renowned journal “Physical Review Letters”. The red shift has great practical relevance in positioning, navigation, the definition of the international atomic time as well as geophysics and Earth observation.
Supporters of the project
The Bremen initiative for the scientific use of the Galileo satellites was taken up by both DLR Space Administration and the European Space Agency ESA and supported with the RELAGAL and GREAT projects. The latter was set up in the ESA General Studies Program and coordinated by the Galileo Navigation Science Office at ESAC near Madrid. The data on orbit and clock rate were processed over three years by the ESOC Navigation Support Office in Darmstadt and made available to the team at ZARM and another group at the Paris Observatory (SYRTE) for parallel independent analysis. In addition to the high-precision clock and orbit data, laser-based position measurements of the satellites were also used.
Contact persons for questions regarding the research project:
Dr. Sven Herrmann
Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation
Sven.Herrmann(at)zarm.uni-bremen.de
+49 421 218-57871
Prof. Claus Lämmerzahl
Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation
Claus.Laemmerzahl(at)zarm.uni-bremen.de
+49 421 218-57834
Contact person for general press inquiries:
Birgit Kinkeldey
Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation
Birgit.Kinkeldey@zarm.uni-bremen.de
+49 421 218-57755
