Orbit design for satellite formations devoted to space environment measurements

Accurate knowledge of the space environment characteristics in terrestrial orbits at different altitudes is of paramount importance for the understanding of geophysical behavior of our planet, as well as for a reliable design of the space vehicles, able to withstand the relevant, challenging conditions. In-situ measurements are required to improve this knowledge and to correctly tune the models of the orbital environment. The metrology devoted to this goal includes advanced instruments, but also builds on a correct distribution, in space and time, of the measurement points. This paper discusses effective orbital design for missions devoted to the sampling of the Low Earth orbits, taking advantage of the capabilities of the formation flying concept that can be nowadays exploited by small satellites. The proposed approach can be adapted to different possible sampling campaigns at the different ranges of interest, and focusses on a passive control enabling extended mission duration and indeed significant, time-long series of collected data. Some examples for optimal acquisition of these orbits are included and analyzed.