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Performance verification of extremely precise atomic clock in microgravity


Project duration: 2010 to 2017

Project manager: Václava Dolejšková

The ELT (European Laser Timing) project is purely Czech contribution to important international experiment ACES (Atomic Clock Ensemble in Space). Its major goal is to verify performance of new generation of extremely precise atomic clock in microgravity and to perform independent time measurements on Earth and in space. ELT device is going to be installed on board the ISS, particularly on the external platform of European Columbus laboratory module.

The ELT instrument as part of the ACES will provide optical link supplementing four microwave links. The ELT flight model is developed by the CSRC in cooperation with Airbus Defence & Space and Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague. The on-board hardware of ELT consists of a CCR (Corner Cube Reflector), an optical detector SPAD (Single-Photon Avalanche Diode), and an event timer board connected to the ACES time scale. Light pulses fired towards ACES by a laser ranging ground station will be detected by the SPAD diode and time tagged in the ACES time scale. At the same time, the CCR will re-direct the laser pulse towards the ground station providing precise ranging information.

Optical link will perform comparison of distant clocks, both space-to-ground and ground-to-ground, to frequency uncertainty levels well below 1×10-16. Because of the high stability of the ACES clock signal, non-common view comparisons of clocks across intercontinental distances will be possible with ELT.

Optical link also finds interesting applications in:

  • The distribution of the ACES time reference and in the synchronization of geodetic observatories
  • Combined with microwave performance, the ELT will contribute to the characterization and cross-comparison of two different time transfer and ranging systems
  • Optical versus dual-frequency microwave measurements also provide useful data for the study of atmospheric propagation delays and for the construction of mapping functions at three different wavelengths 

Czech Space Research Centre

CSRC is a privately owned company situated in Brno and Kroměříž. CSRC was founded in 1994 to transfer space technology and standards to the Czech space industry. CSRC main domain is a complex realization of space electronics projects based on electronics design with cooperation of Faculty of Electrical Engineering and Communication, Brno University of Technology. CSRC successfully produced number of instruments and tools made by experts and certified by ESA, for example Integral, SMART-1, Swarm, DEMETER, PROBA-2, SATRAM or Solar Orbiter. Complex activities include also tests, simulations, analyses and mechanical designs. CSRC has implemented ESA ECSS standards related to the cleanroom manufacturing activities including certified system of quality. CSRC, as an ESA audited Czech company, is an attractive business partner for the whole international space industry.

What would you name as main benefits of the project to you and your company?

“Participating in this complex project, CSRC has gained great technical experience in design, development, and manufacturing of electronic devices for operation in space. Working on this project is not only an exciting challenge, but it is also a very prestigious opportunity, for a relatively small Czech company, to be part of a team working on equipment that is going to be used on the ISS. We have also learned important aspects of project management, design and development and documentation creation according to ECSS standards. We are also very honoured to work together with world leaders in this field. This project is under the umbrella of the European Space Agency and our closest Czech partner is a scientific team lead by Professor Ivan Procházka from the Czech Technical University who is the world’s renowned leader in this field.”