Optimizing scientific results of the ACES/PHARAO space mission M/F

Job Description

Missions

Atomic Clock Ensemble in Space (ACES) is a joint ESA/CNES space mission whose main objective is an improved test of the gravitational redshift of clocks as predicted by Einstein's theory of general relativity (GR). The mission consists of a high performance cold-atom clock (called PHARAO and built in France with LTE expertise) onboard the international space station that is compared to ground clocks, thereby testing the prediction of GR at the 10-6 level. This will improve best previous tests using clocks onboard Galileo satellites [Delva 2018] or clocks on the Tokyo Sky-tree [Takamoto 2020] by an order of magnitude or more.
ACES was launched on April 21, 2025. It is still being commissioned, but already acquiring science data since October 2021. ACES is expected to enter science phase for a minimum duration of two years in 2026. LTE is strongly involved, from the conception of PHARAO to the detailed analysis of the raw data in order to extract the best possible estimate of the ground-space clock frequency difference and thus to check whether the GR prediction is correct. To do so the space clock is compared to ground clocks using a Microwave Link (MWL) and a pulsed optical link (ELT). At LTE we process the raw data of the MWL and generate science products [Meynadier 2018] from which the scientific results (GR test and other science objectives) can be obtained [Savalle2019, Enzer 2025]. The corresponding software has been developed at LTE over more than a decade.

[Delva 2018] https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.231101
[Takamoto 2020] https://doi.org/10.1038/s41566-020-0619-8
[Meynadier 2018] https://iopscience.iop.org/article/10.1088/1361-6382/aaa279
[Savalle 2019] https://iopscience.iop.org/article/10.1088/1361-6382/ab4f25
[Enzer 2025] https://iopscience.iop.org/article/10.1088/1361-6382/ae2c36

Activity

We are looking for a highly motivated researcher (post-doc level) to carry out and optimize the final scientific data analysis, i.e. from science products to final scientific results. Indeed the data is affected by different types of noise and has large gaps (see [Savalle2019] for details) so the optimal statistical methods for its analysis are still to be found [Savalle2019, Enzer 2025]. On top of that, many systematic effects need to be taken into account, in the space clock itself, but also in the MWL, ground clocks and orbit determination. Optimizing these final analysis steps, applying them to the data and publishing the final results will be the main activity of the post-doc, additionally to contributing to the raw data processing on an operational basis.

Your Profil

Skills

Previous experience with scientific and instrumental data analysis is expected. A background in time/frequency metrology and/or cold atom physics (clocks and/or atom interferometers) would be a plus. Strong motivation to work on an exciting cutting-edge space mission is mandatory.

Your Work Environment

The work will be carried out in the “Theory and Metrology” group at LTE, which has been strongly involved in ACES data simulation and data analysis over many years. The position is initially for one year, starting as soon as possible, with the possibility of extension to two or more years. For further information, contact Marc Lilley (marc.lilley@obspm.fr) and Peter Wolf (peter.wolf@obspm.fr).

Compensation and benefits

Compensation

between 3130 € and 4340 € gross monthly sallary depending on experience

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

The research professions