TOLOSAT project: Gravimetry and communication

The use of Constellations for weather science, security and disaster monitoring is a major challenge for space application services. Satellite to satellite communication using existing constellations has not been extensively explored yet. It can improve the communication times for small-satellite missions which have limited access to ground stations. Thus, a mission to demonstrate the feasibility of this link is required. Another element of interest in space application is Earth Observation, especially in the context of Climate Change. Gravimetry allows an understanding of mass transport in the Earth System through the remote sensing of the time variation of the Earth gravity field. CubeSats are low-cost small-scale and hence lower risk solutions to Earth Observation missions. University CubeSats have shown their success in demonstration and scientific missions, and have a great potential in providing students with practice and application on real space systems. In this context, the student associations ASTRE and SUPAERO CubeSat Club have joined in a CubeSat program called TOLOSAT, with the hope of demonstrating such technologies. Gathering 70 students from Toulouse, the team was split into subsystems in accordance with the concurrent engineering principles. The work performed followed recommendations from experts from the French National Centre for Space Studies (CNES) and the industry. The TOLOSAT payloads have to test and demonstrate new means of measuring gravity and addressing communication issues. Firstly, for the gravimetry mission, our approach relies solely on GNSS to compute the gravity field, avoiding expensive gravimeters. For the communication mission: the Iridium constellation will be used as an intermediate between the CubeSat and the ground station. Off-the-shelf components such as patch antennas are planned to prove their efficiency in orbit. This would improve the coverage and the communication window. The preliminary design was completed. TOLOSAT