MICROSCOPE mission: Statistics and impact of glitches on the test of the weak equivalence principle

TL;DR

The MICROSCOPE space experiment tests the weak equivalence principle by measuring differential accelerations, with glitches affecting the data; understanding and discarding glitch-affected data improves test accuracy.

Contribution

This study characterizes the shape, timing, and impact of glitches on the MICROSCOPE WEP test, highlighting the importance of data cleaning to mitigate their effects.

Findings

Glitches are short-lived, randomly timed events modulated by orbital and spin periods.

Glitches impact the WEP test results, but their effect level is uncertain.

Discarding glitch-affected data is the most effective mitigation strategy.

Abstract

MICROSCOPE's space test of the weak equivalence principle (WEP) is based on the minute measurement of the difference of accelerations experienced by two test masses as they orbit the Earth. A detection of a violation of the WEP would appear at a well-known frequency $f_{\rm EP}$ depending on the satellite's orbital and spinning frequencies. Consequently, the experiment was optimised to miminise systematic errors at $f_{\rm EP}$. Glitches are short-lived events visible in the test masses' measured acceleration, most likely originating in cracks of the satellite's coating. In this paper, we characterise their shape and time distribution. Although intrinsically random, their time of arrival distribution is modulated by the orbital and spinning periods. They have an impact on the WEP test that must be quantified. However, the data available prevents us from unequivocally tackling this task. We show that glitches affect the test of the WEP, up to an a priori unknown level. Discarding the perturbed data is thus the best way to reduce their effect.