Testing gravity with cold-atom clocks in space. The ACES mission

Luigi Cacciapuoti , Michele Armano , Rudolf Much , Omar Sy , Achim Helm , Marc Peter Hess , Johannes Kehrer , Silvio Koller , Thomas Niedermaier , Francois Xavier Esnault (1) , Didier Massonnet (1) , Didier Goujon , Jacques Pittet , Pascal Rochat , Shuo Liu , Wolfgang Schaefer , Theo Schwall , Ivan Prochazka , Anja Schlicht , Ulrich Schreiber , Pacome Delva (2) , Christine Guerlin (3, 2) , Philippe Laurent (2) , Christophe Le Poncin-Lafitte (2) , Marc Lilley (2) , Etienne Savalle (2) , Peter Wolf (2) , Frederic Meynadier , Christophe Salomon (3)

1 CNES - Centre National d'Études Spatiales [Toulouse]
2 SYRTE - Systèmes de Référence Temps Espace
3 LKB (Lhomond) - Laboratoire Kastler Brossel

Atomic Clock Ensemble in Space (ACES) is a mission designed to test Einstein's theory of General Relativity from the International Space Station (ISS). A primary frequency standard based on laser cooled caesium atoms (PHARAO) and an active H-maser (SHM) generate a clock signal that is distributed to a network of clocks on the ground to perform space-to-ground comparison. With a fractional frequency stability of 1 × 10^-16 after 10 days of integration time and an accuracy of 1 - 2 × 10^-16, ACES will provide an absolute measurement of the gravitational redshift, it will search for time variations of fundamental constant, and perform Standard Model Extension (SME) tests. The ACES payload is currently completing its qualification tests before flying. The mission status, the latest test results, and the ACES performance for testing General Relativity are discussed.

Contribution to the Topical Issue "Quantum Technologies for Gravitational Physics", edited by Tanja Mehlstäubler, Yanbei Chen, Guglielmo M. Tino, Hsien-Chi Yeh.

Domains: Sciences of the Universe [physics]

Luigi Cacciapuoti, Michele Armano, Rudolf Much, Omar Sy, Achim Helm, et al.. Testing gravity with cold-atom clocks in space. The ACES mission. The European Physical Journal D : Atomic, molecular, optical and plasma physics, 2020, 74, ⟨10.1140/epjd/e2020-10167-7⟩. ⟨insu-03713098⟩