Quantum space sensor to combat climate change

A team of European scientists is developing new space sensors that use quantum technologies to measure acceleration with high precision. This research is a crucial step towards future space missions that will track subtle changes in Earth's gravitational field. These advanced tools will provide a sharper picture of our planet's changes, providing more accurate data on glaciers, sea level rise and groundwater level fluctuations with greater precision and urgency.

• The ability to measure tiny differences in gravity helps us detect the presence of groundwater, determine the amount of ice melting in the polar regions, or even find natural resources.

• The CARIOQA consortium is working to improve gravity mapping by exploiting the special sensitivity of quantum accelerometers to create a “higher resolution” gravity map of the Earth.

• To measure gravity from space, it is crucial to accurately track a satellite's acceleration. This is done using accelerometers that monitor a test mass in free fall on board the satellite.

• By attaching a quantum accelerometer to a satellite, scientists will then be able to study glacier movements, sea level rise and changes in groundwater levels, combating climate change like never before.

• An EU-funded consortium with a budget of €17 million hopes to put the world's first quantum accelerometer into orbit by 2030.

An ambitious new project launched by the European Commission and supported by the Quantum Flagship aims to transform Earth monitoring by providing more accurate data on changes in ice melting, groundwater depletion and ocean currents.

The new €17 million project, called CARIOQA-PMP, aims to improve conventional methods of measuring gravity by incorporating the extraordinary capabilities of quantum sensors.

Materials on Earth, such as rocks, minerals, and water, have different densities from place to place. Earth's gravitational field is affected by the mass of these materials. The more mass there is in an area, the stronger the gravitational force at a particular location. When large masses move or change, such as when ice melts and flows into the sea, or when groundwater is depleted, this changes local gravity.

Conventional gravity mapping can detect these differences, which can provide us with important information such as where underground water might be, how much ice is melting in the polar regions, or even help us find natural resources.

However, when looking at the Earth from space, the picture of gravity is somewhat unclear. Although sophisticated, conventional gravimeters have problems with weak gravitational signals from the Earth when measuring fine-scale fluctuations in different regions.

However, this new and improved quantum accelerometer will be the first of its kind to have its capabilities enhanced using quantum physics. This tool will allow scientists to create a complete gravitational map of the Earth at a much “higher resolution.”

Christine Fallet, CARIOQA-PMP project coordinator, said: “Conventional gravimeters or classical electrostatic accelerometers have some limitations in sensitivity and precision. However, they provide information that allows us to detect large ocean currents from Earth; smaller or more subtle features may not be captured in enough detail or missed altogether. This is not satisfactory for accurate Earth monitoring and studying tiny changes in gravity caused by subtle shifts such as small amounts of melting ice or minor groundwater depletion.

“The goal of the CARIOQA project is to develop groundbreaking quantum accelerometers for space that can revolutionize satellite-based geoscience. These advances will play a critical role in monitoring climate change and support global efforts to develop mitigation and adaptation strategies.”

The new CARIOQA quantum technology is still under development. The team uses a technique called Cold Atom Interferometry (CAI). CAI is based on the principles of quantum mechanics to study and exploit the wave-like behavior of atoms at extremely low temperatures.

When atoms are cooled to near absolute zero, they move almost in slow motion, allowing extremely precise measurements with lasers. “When cooled,” Fallet said, “the wave-like nature of the atoms can be exploited to create interference patterns (similar to overlapping waves in water). By analyzing these patterns, we can measure the acceleration of the atoms with great precision.”

Cold atom interferometry avoids some of the problems of older systems and provides clearer, more reliable data over time. When it comes to measuring gravity, CAI is like upgrading from a fuzzy old TV to a crystal-clear HD screen. This technology will give us a much sharper view of what's happening to our planet.

Europe's leading role in quantum

The project consists of two parallel parts: CARIOQA-PMP (Pathfinder Mission Preparation) focuses on developing quantum acceleration technology for use in space within the next decade. This project will lay the foundation for the quantum pathfinder mission, while CARIOQA-PHA continues the effort to demonstrate the feasibility of a quantum space gravimetry pathfinder mission, with the aim of enabling the European Union to deploy quantum gravimeters and accelerometers in space.

“This project aims to provide a powerful Earth observation tool. It is a crucial step for the European Union to establish itself as a leader in quantum space technology. The success of CARIOQA could put Europe at the forefront of global efforts to combat climate change, while demonstrating the power of quantum technology in tackling one of the most pressing challenges of our time,” said Fallet.

CARIOQA brings together a consortium of important partners, including the French Space Agency (Centre National d'etudes Spatiales – CNES), the German Aerospace Center (DLR), industry (Airbus Defence and Space in France and Germany (ADS-F, ADS-G), EXAIL, TELETEL, LEONARDO, GMV), European laboratories and universities (LUH, SYRTE, LP2N, LCAR, ONERA, FORTH, TUM, POLIMI, DTU) and experts in impact maximisation (FORTH/PRAXI, groupe GAC).