Atomic Clock Ensemble in Space

Atomic Clock Ensemble in Space

Atomic Clock Ensemble in Space is a project led by the European Space Agency which will place an ultra-stable atomic clock on the International Space Station. Operation in the microgravity environment of the ISS will provide a stable and accurate time base for different areas of research, including general relativity and string theory tests, time and frequency metrology, and very long baseline interferometry.

The payload actually contains two clocks: a caesium clock for long-term stability and a hydrogen maser for short-term stability.

The clock is planned to travel to the space station aboard a Japanese HTV,[1] and is to be externally mounted to the ESA's Columbus Laboratory.

ACES is expected to be ready for launch in 2016 and have an 18-30 month operations phase.[2]

See also

Scientific research on the ISS

External links

  • ACES page at the ESA
  • ACES factsheet by the ESA (PDF)


  1. ^ ESA.INT - Atomic Clock Ensemble in Space (ACES) - September 6th, 2010
  2. ^ - ACES PLATFORM - December 19th, 2013