MOQAST-GEM Mass Observation by QuAntum Sensors and Time measures from space - Gravity field of the Earth and Mars - Italy and the Quantum breakthrough in space gravimetry. Benefits of an innovative Quantum Space Gravimetry concept for the determination of the static and time-variable grativy field of the Earth and for Mars gravity exploration, exploiting Italian technology and know-how

Contributo migliorativo di una missione QSG nello studio del campo di gravità, con tre casi di studio: • campo di gravità tempo variante (idrologia continentale, Italia del nord), • campo di gravità statico (Africa, rift valley), • planetologia (Marte, esplorazione per la ricerca di acqua).

The aim of the proposal is to carry out a research project furthering the knowledge of both the static and time-variable Earth gravity field and improving the knowledge of the gravity field of Mars, determining the benefits of a Quantum Space Gravimetry (QSG) mission. The proposal is based on the concept of an innovative payload on board a constellation of satellites, exploited to obtain observations on the Earth gravity field and gravity field potential. The payload is represented by Cold Atom Interferometers (CAI) and atomic clocks, the atomic species being Strontium. The Cold Atom Interferometers act as single-axis gradiometers, capable of observing second derivatives of the Earth gravitational potential, while pairs of atomic clocks on two different satellites along an orbit can provide measurements of differences of the gravitational potential. Both the Sr gradiometer and optical clocks need specific experimental developments and tests in order to prove them suitable for future space missions. In fact, the performance of a Sr atomic interferometer has not yet been fully characterized in the laboratory, as in the case of the Rb. In order to characterize the influence of system and environmental parameters on the sensitivity and long-term stability of the Sr atomic gradiometer, in this project a series of experimental developments and tests will be carried out. Based on the characterization of the experimental apparatus, a series of numerical simulations will be performed in order to identify Ministero dell'Università e della Ricerca MUR - BANDO 2022 possible mission scenarios and their characteristics, for the case of different satellite formations (e.g., Bender configuration, double pair formation, pendulum formation), keeping in mind that in the case of a quantum gravimetry mission like the one proposed here, the goal for the gravity field estimation is to improve the low frequencies of the harmonic model. For the simulations, the data analysis will be performed by applying the space-wise strategy. The results of the experimental tests and of the numerical simulations will also be used to define a preliminary mission profile and satellite design. In the end, it will be possible to assess the improvement provided by a QSG mission in: (i) improving the time-variable Earth gravity field, enabling the monitoring of specific geophysical phenomena in a small area and assessing the possibility to model the seasonal variations of hydrological basins; (ii) improving the static Earth gravity field, furthering the scientific readiness for natural resource exploration in countries lacking full geophysical data coverage; (iii) improving the gravity maps of Mars, hence the knowledge of the surface and subsurface of the planet to investigate the presence of sub-surface water, which is fundamental for the creation of extra-terrestrial habitats.