In a vacuum, do a kilo of feathers and a kilo of lead fall at the same speed? This is the fundamental question the Microscope satellite is setting out to answer.
Microscope is designed to test in space the validity of the founding principle of the theory of general relativity developed by Albert Einstein between 1907 and 1915, in which he assumed the equivalence of a gravitational field and a corresponding acceleration of the reference system. The challenge for Microscope will be to achieve a level of precision 100 times better than any experiment yet performed on Earth, thus opening new vistas for theories of gravitation.
The test of the equivalence principle is based on the universality of free fall. On Earth, the principle has been verified with a relative degree of precision on the order of 10-13. Microscope will be even more precise, testing the principle in the vacuum of space where free fall is a lot less perturbed and lasts a lot longer. It will thus be able to study the relative motion of two bodies on the satellite in permanent free fall over the course of several months.
CNES developed the full system and built the satellite. It provided nearly 90% of funding and was also prime contractor in charge of satellite bus development, integration and testing, and construction and operation of the mission operations control centre. Microscope was developed in collaboration with the French aerospace research agency ONERA as mission principal investigator responsible for the instrument and science mission centre, in partnership with the Geoazur research laboratory, and with ESA, which supplied the satellite’s microthrusters, and the German space agency DLR and two research laboratories, the ZARM centre of applied space technology and microgravity and the German metrology agency PTB.
After departing the Toulouse Space Centre for French Guiana, the satellite was prepped and tested by CNES teams in the EPCU S5 payload preparation building at the Guiana Space Centre, after which it was mated with the Soyuz launcher in readiness for launch on Friday 22 April.
Webcast : Microscope satellite launch live on 22 April 2016 : https://microscope.cnes.fr/