The European Space Agency announced yesterday a significant milestone in the development of the next Mars mission: the core module of the ExoMars Trace Gas Orbiter has been delivered to Thales Alenia. The core module consists of the structure, thermal control, and propulsion systems; a lot of assembly and testing remains before the 2016 launch. It needs electronics, power systems, instruments, telecom, and so on. But it’s beginning to look a lot like a spacecraft.