The HERMES Mission: A CubeSat Constellation For Multi-Messenger Astrophysics

The High Energy Rapid Modular Ensemble of Satellites (HERMES) is a project that plays a key role in the Multi-Messenger Astrophysics of the next decade. The implementation of a distributed space asset to continuously monitor the random electromagnetic emissions of bright high-energy transients in the Universe is proposed. Specifically, the technological and scientific pathfinder constellation, up to six 3U CubeSat, embarks a new generation of miniaturised detectors for science. Having just closed the PDR, the project goes into phase C&D: Politecnico di Milano, together with INAF, oversees the space segments and payload implementation, respectively. The challenging mission feasibility was assessed from both technological and scientific points of view. The possibility to correctly keep the spacecraft triplets geometry and to ensure the correct overlapping of instrument field-of-view for a successful triangulation of highenergy transient has been achieved with no orbital control on board. The paper, starting from an introduction on scientific mission constraints, focuses on the description of platform subsystems design. The constellation complexity is highlighted in terms of pointing accuracy, power demand, and scientific data packages transmission. The program is co-funded by the National Ministry for Research (MIUR), the Italian Space Agency, (HERMES-TP), and the EC-H2020 framework (HERMES-SP).