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Submitted on 26 Nov 2014
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Testing gravity beyond the standard model: status of GAP, an electrostatic accelerometer for interplanetary
fundamental physics
Joël Berge, Francoise Liorzou, Bruno Christophe
To cite this version:
Joël Berge, Francoise Liorzou, Bruno Christophe. Testing gravity beyond the standard model: status of GAP, an electrostatic accelerometer for interplanetary fundamental physics. The 40th COSPAR Scientific Assembly (COSPAR 2014), Aug 2014, MOSCOU, Russia. �hal-01087780�
40th COSPAR Scientific Assembly 2014
Fundamental Physics in Space (H)
Space Missions for Fundamental Physics (H0.3)
TESTING GRAVITY BEYOND THE STANDARD MODEL: STATUS OF GAP, AN ELECTROSTATIC ACCELEROMETER FOR INTERPLANETARY FUN- DAMENTAL PHYSICS
Joel Berge, joel.berge@onera.fr ONERA, Chatillon, France
Fran¸coise Liorzou, francoise.liorzou@onera.fr ONERA, Chatillon, France
Bruno Christophe, bruno.christophe@onera.fr ONERA, Chatillon, France
Theories beyond the standard model aim to face several challenges: connect gravitation with the other three known forces, and shed light on dark matter and dark energy. Although General Relativity has been incredibly successful at passing laboratory / Solar System scales tests to date, it is a classical theory (hence, incompatible with quantum physics scales) and it fails at explaining large scale astrophysical observations such as galaxy rotation curves and the acceler- ated expansion of the Universe without introducing dark matter and dark energy. Thus, most theories beyond the standard model explore modifications to General Relativity. Those modifi- cations, whether they consist in adding an extra scalar field or adding a scale-dependence to the gravitation laws, allow us to predict small deviations from General Relativity at laboratory / Solar System scales. For instance, such a deviation could have explained the Pioneer anomaly, where the Pioneer probes were measured to undergo an unexpected acceleration. Although this anomaly has recently been accounted for by an instrumental thermal radiation, precise measurements of the non-gravitational forces applied to the probes would have helped decide whether the observed behavior was due to gravitational or non-gravitational physics. As a result, several missions have been proposed to embark an accelerometer on-board an interplan- etary probe. Indeed, an accelerometer will measure the non-gravitational accelerations applied to the probe, thereby separating the potentially measured departures from a pure geodetic trajectory into their gravitational and non-gravitational components, and allowing us to eas- ily constrain General Relativity in deep space. The Gravity Advanced Package (GAP) is an instrument developed for this purpose. It is composed of a 3-axes electrostatic accelerometer called MicroSTAR and a rotating platform called Bias Rejection System. It aims to provide an unbiased measurement of a spacecraft’s non-gravitational acceleration. MicroSTAR inherits from Onera’s in-orbit accelerometers (CHAMP, GOCE, GRACE), improved to reduce power consumption, size and mass. The addition of the Bias Rejection System rotating platform is a technological upgrade which allows MicroSTAR to make unbiased measurements at low
frequencies: the Bias Rejection System rotates MicroSTAR such that the signal of interest is separated from the bias of the instrument in the frequency domain. We will first present the science goals and opportunities for GAP. We will then give an update on the status of GAP.
In particular, we will detail its current development, as well as the experiments we undertake to assess its performance.
