The MARVEL gravity and reference frame mission proposal

<p>The "MARVEL gravity and reference frame mission" proposal has been selected by CNES for the start of a pre-phase A study. <br>MARVEL aims at reaching in one single mission two major and complementary goals:<br>- The monitoring of mass transfers within the Earth system with increased precision,<br>- The realization, at the millimeter level, of the terrestrial reference frame.</p><p>In the nominal configuration, a LEO satellite (400 - 450 km) in polar orbit, acting as a gravity sensor, performs optical ranging measurements on two MEO satellites (7000 km) orbiting on the same plane. The MEO satellites are equiped with the four geodetic techniques (GNSS, SLR, DORIS, VLBI), in order to meet the GGOS Earth reference frame accuracy objectives.</p><p>We also propose two alternative (and less costly) configurations, where only the first goal is fully reached:<br>- one by replacing the MEO satellites by two or more cubesats on the same orbit,<br>- the second one by using specially equipped GNSS satellites as targets for the LEO optical ranging measurements.</p><p>In any case, the goal of monitoring mass change with enhanced precision is attained through the use of high-low SST laser tracking.</p><p>We will present in detail the different configurations proposed and present the simulation plan for this pre-phase A study.</p>