MICROSCOPE (satellite)

MICROSCOPE (Micro-Satellite à traînée Compensée pour l'Observation du Principe d'Equivalence)[1] is a 300 kg class microsatellite launched by the European Space Agency on 25 April 2016 to test the universality of free fall (the equivalence principle) with a precision of the order of 10−15, 100 times more precise than can be achieved on Earth.

Experiment

To test the Equivalence Principle (i.e. the similarity of the free fall for two bodies of different composition in an identical gravity field), two differential accelerometers are used successively. If the equivalence principle is verified, the two sets of masses will be subjected to the same acceleration. If different accelerations have to be applied, the principle will be violated.

The principal experiment is the T-SAGE instrument (Twin-Space Accelerometer for Gravity Experiment), built by ONERA, that is composed of two differential accelerometers and their two associated, concentric cylindrical masses. One accelerometer has masses made of different materials; one is titanium, the other a platinum-rhodium alloy. The masses are maintained within their test area by electrostatic repulsion, intended to maintain them motionless with respect to the satellite inside the independent differential electrostatic accelerometers. The other accelerometer has two weights made of the same material, platinum.

It was necessary to create a thermally benign environment for the accelerometers. They are mounted on the side of the satellite bus away from the sun; there is thermal isolation from the satellite; and, the modes of thermal connection were minimised and modelled to the extent of minimising wire connections with the satellite.

Satellite control

The satellite has an Acceleration Attitude Control System (AACS) that uses eight microthrusters to 'fly' the satellite around the test masses, taking account of the dynamic forces (e.g. aerodynamic forces due to the residual atmosphere, solar pressure forces due to the photon impacts, electromagnetic forces within the Earth's magnetosphere, and gravitational forces in the Sun-Earth-Moon system.)[1]

Launch

The launch at 2102UTC on 25 April 2016 used a Soyuz-2 carrier rocket, and Fregat upper stage, was designated VS14, from the Arianespace launch centre in Kourou, French Guiana. The main payload was Sentinel-1B, and there were also several cubesats, OUTFI-1, e-st@r-II, and AAUSAT-4.[2]

See also

References

  1. 1 2 MICROSCOPE, CNES, accessed 26 April 2016.
  2. ↑ Flight VS14 – A successful Arianespace launch with Soyuz, supporting sustainable development, fundamental physics and promoting space careers, Arianespace media release, 25 April 2016

External links

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