RadioAstron gravitational redshift experiment: status update

https://arxiv.org/abs/1605.05832

(Submitted on 19 May 2016)

A test of a cornerstone of general relativity, the gravitational redshift effect, is currently being conducted with the RadioAstron spacecraft, which is on a highly eccentric orbit around Earth. Using ground radio telescopes to record the spacecraft signal, synchronized to its ultra-stable on-board H-maser, we can probe the varying flow of time on board with unprecedented accuracy. The observations performed so far, currently being analyzed, have already allowed us to measure the effect with a relative accuracy of 4×10−4. We expect to reach 2.5×10−5 with additional observations in 2016, an improvement of almost a magnitude over the 40-year old result of the GP-A mission.