Space test of the equivalence principle: first results of the MICROSCOPE mission
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The weak equivalence principle (WEP), stating that two bodies of different compositions and/or mass fall at the same rate in a gravitational field (universality of free fall), is at the very foundation of general relativity. The MICROSCOPE mission aims to test its validity to a precision of 10 −15 , two orders of magnitude better than current on-ground tests, by using two masses of different compositions (titanium and platinum alloys) on a quasi-circular trajectory around the Earth. This is realised by measuring the accelerations inferred from the forces required to maintain the two masses exactly in the same orbit. Any significant difference between the measured accelerations, occurring at a defined frequency, would correspond to the detection of a violation of the WEP, or to the discovery of a tiny new type of force added to gravity. MICROSCOPE’s first results show no hint for such a difference, expressed in terms of Eötvös parameter (both 1 uncertainties) for a titanium and platinum pair of materials. This result was obtained on a session with 120 orbital revolutions representing 7% of the current available data acquired during the whole mission. The quadratic combination of 1 uncertainties leads to a current limit on of about .
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The MICROSCOPE reference instrument provided a null result, γ_Pt,Pt = [0.0 ± 1.1 ± 2.3_syst] × 10^−15, showing no sign of unaccounted systematics.
“Besides, the reference instrument provided a null result, g Pt;Pt ¼ ½0:0 Æ 1:1 Æ 2:3 syst Þ Â 10 À15 showing no sign of unaccounted systematics.”
From Fundamental constants: from measurement to the universe, a window on gravitation and cosmology (2025) · cites this paper as Touboul et al. 2019
The MICROSCOPE experiment provided a constraint on the Eötvös parameter between titanium and platinum of γ_Ti,Pt = (−1.5 ± 2.3 ± 1.5_syst) × 10^−15.
“g Ti;Pt ¼ ðÀ1:5 Æ 2:3 Æ 1:5 syst Þ Â 10 À15 ;ð11Þ”
From Fundamental constants: from measurement to the universe, a window on gravitation and cosmology (2025) · cites this paper as Touboul et al. 2019
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Touboul, P., Métris, G., Rodrigues, M., Bergé, J., Robert, A., Baghi, Q., André, Y., Bedouet, J., Boulanger, D., Bremer, S., et al. (2022) · Physical Review Letters · doi:10.1103/physrevlett.129.121102 · Cited by 205 · see citing works
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- Authors
- Touboul, P., Métris, G., Rodrigues, M., André, Y., Baghi, Q., Bergé, J., Boulanger, D., Bremer, S., Chhun, R., Christophe, B., Cipolla, V., Damour, T., Danto, P., Dittus, H., Fayet, P., Foulon, B., Guidotti, P.-Y., Hardy, E., Huynh, P.-A., Lämmerzahl, C., Lebat, V., Liorzou, F., List, M., Panet, I., Pires, S., Pouilloux, B., Prieur, P., Reynaud, S., Rievers, B., Robert, A., Selig, H., Serron, L., Sumner, T., & Visser, P.
- Affiliations
- Université Paris-Saclay (FR)
- Centre National de la Recherche Scientifique (FR)
- Centre National d'Études Spatiales (FR)
- University of Bremen (DE)
- Institut des Hautes Études Scientifiques (FR)
- Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) (DE)
- Institut national de l’information géographique et forestière (FR)
- Imperial College London (GB)
- Delft University of Technology (NL)
- ORCID
- Venue
- Classical and Quantum Gravity
- Publisher
- IOP Publishing
- Published
- 2019-10-18
- Volume
- 36
- Issue
- 22
- Pages
- 225006
- ISSN
- 0264-9381 (ISSN-L)
- 1361-6382
- OpenAlex
- W2977093787
- Cited by
- 83
- References
- 63
- Citations by year
- 2026: 5 · 2025: 8 · 2024: 11 · 2023: 5 · 2022: 23 · 2021: 17 · 2020: 13 · 2017: 1
- FWCI
- 7.07
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Licence
- Locations
- Classical and Quantum Gravity (publishedVersion)
- elib (German Aerospace Center) (acceptedVersion)
- arXiv (Cornell University) (submittedVersion)
- HAL (submittedVersion, other-oa)
- Spiral (Imperial College London) (submittedVersion)
- arXiv (Cornell University)
- Funders
- Deutsche Forschungsgemeinschaft (FKZ 50 OY 1305, LA 905/12-1)
- Centre National d’Etudes Spatiales
- Centre National de la Recherche Scientifique
- Office National d'études et de Recherches Aérospatiales
- Topics
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Relativity and Gravitational Theory
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Pulsars and Gravitational Waves Research
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Cosmology and Gravitation Theories
- Keywords
- weak equivalence principle, MICROSCOPE mission, Eötvös parameter, tests of general relativity, satellite gravimetry
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