NASA. ESA. Atomic Clock Ensemble in Space (ACES) / Human Spaceflight Research / Human Spaceflight. Atomic Clock Ensemble in Space (ACES) Atomic Clock Ensemble in Space (ACES) is a fascinating new ESA mission developed in cooperation with the French Space Agency (CNES) that will expand the range of research on the International Space Station (ISS).
The ACES clocks will be installed on the external payload facility of the Columbus module. The frequency reference generated on-board the ISS will be used by a worldwide network of ground terminals to perform comparisons with the best available atomic clocks on the ground. Time flies on the ISS.