Results of the MOCAST+ study on a quantum gravimetry mission

MOCAST+ (MOnitoring mass variations by Cold Atom Sensors and Time measures) is a recently concluded study funded by the Italian Space Agency (ASl) and jointly carried out by several Italian research groups, focusing on a gravimetry mission based on quantum technology.

In the past twenty years, space missions like GRACE and GRACE-FO have formed a well-organized user community tracking the Earth mass movement to study environmental changes on a global scale using data from satellite measurements. In fact, monitoring global parameters underlying climate change, water resources, flooding, melting of ice masses and the corresponding global sea level rise is of paramount importance, since remote sensing of the changes of the Earth gravitational field provides basic data on, e.g., geodynamics, earthquakes, hydrology or ice sheets changes.

Since classical sensors have reached a high level of maturity with a limited potential for further improvement, a large interest has developed in novel technologies based on quantum technologies and quantum sensing. These technologies promise to offer higher sensitivity and drift-free measurements, and higher absolute accuracy for terrestrial as well as space missions, thus giving direct access to more precise long-term measurements and comparisons.

Europe is at the forefront of quantum technologies, and activities towards the deployment of pathfinder quantum gravimetry mission within this decade are being funded at various levels. Looking at a time frame beyond the present decade, in the MOCAST+ study we have analyzed the performance of a quantum enhanced payload consisting of a Cold Atom Interferometer based on strontium atoms and acting as a gravity gradiometer, plus an optical frequency measurement using an ultra-stable laser, in order to also provide time measurements. The main goals of the study were to define the level of accuracy which can be expected from such a payload and the level of accuracy which is needed in order to detect and monitor phenomena identified in the Scientific Challenges of the ESA Living Planet Program, in particular Cryosphere, Ocean and Solid Earth.

We will present the results of the study in terms of proposed payload, mission profile and preliminary platform design, results of end-to-end simulations and assessment of the impact of the proposed mission for geophysical applications.