A quantum accelerometer was sent into space to measure Earth's gravity

On January 16, the Europeans launched a race against China and the United States to be the first to possess the original technology to measure the movements of huge masses on the Earth's surface from space. (monsoons, melting ice caps, volcanoes, etc.). . Such observations already exist thanks to the Grace satellites (2002-2017), and then the Grace Follow-on (launched in 2018), but the European partners in the Carioqa project are aiming for ten to a hundred times better accuracy thanks to a new method of observation. Measuring satellite accelerations, and thus the effect of Earth's gravity on them.

Today, as in airbag actuators or cell phones (for switching from horizontal to vertical mode for example), acceleration is measured by the movement of a microscopic mass in a component, which causes variations in electrical potential. Carioca will use cold atoms as a reference. This principle already works in gravity measuring devices developed by Muquans (owned by the French group Exail) and used by geologists, especially on the slopes of Etna in Sicily.

The atoms, cooled near absolute zero by lasers and magnetic fields almost to freezing point, behave like waves rather than particles. Hence the qualifier “quantum” to designate this new generation of sensors.

This wave is separated into two parts, which are then reassembled in order to see the differences in acceleration experienced by the two parts of the wave. In space, researchers hope that this interference will last from two to five seconds, compared to about a hundred microseconds on Earth, in order to increase the accuracy of the measurement.

Upgrading to space standards is necessary

Outside, on account of the different parts of France (CNES) and the French Federation (DLR), the national offices and aerospace searches, Airbus or the labor systems at the time of the Observatoire's space. from Paris. The €17 million project must test the principle in orbit by 2030, before an operational system, possibly consisting of two satellites spaced 200 kilometers behind each other, becomes operational around 2040.

To turn the Muquans device into a space-ready accelerometer, researchers will have to make the whole device more compact, bring it up to space standards (resistance to vibrations, radiation, etc.) and take into account the fact that atoms in orbit do not “fall” into the satellite as On the ground. The whole body will weigh about 160 kg.