The HERMES tanker orbit
The ideal orbit for the HERMES tanker is a GTO orbit. Through flight dynamics analysis we have selected orbital injection parameters exhibiting evolution of inclination within a very narrow band, making rendezvous relativley easy and cost efficient as regards fuel.
We have chosen the HERMES tanker spacecraft to be frozen so the fuell will be solid. This has never happened intentionally before. This solution offers both simplicity and low cost. The GTO-orbit has long eclipse durations and if a thermal subsystem would be required it would impose high performance and cost requirements. Our tanker design embodies certain manufacturing design and operational principles that allow the hardware to survive under low temperatures and thermal cycling for many years. The only feature of control is a passive nutation dumper for correcting any imperfection of the spin axis during the separation from the upper stage.
The passive nature of the tanker spacecraft (no power to activate valves or heaters, no presence of pyrotechnical devices, no electromagnetic compatibility issue) ensures the safety at the launch site and on the launcher.
The HERMES tanker will fly without need of traditional TT&C link for monitoring & control. Its precise position will be verified periodically through ground based optical telescopes, which will benefit from retro-reflectors on the edges of the structure of the tanker spacecraft.