Exploded, schematic view of Gaia. a) Payload thermal tent (Sect. 3.3); b) payload module: optical bench, telescopes, instruments, and focal plane assembly (Sect. 3.3); c) service module (structure): also housing some electronic payload equipment, e.g. clock distribution unit, video processing units, and payload data-handling unit (Sect. 3.2); d) propellant systems (Sect. 3.2.1); e) phased-array antenna (Sect. 3.2.2); and f) deployable sunshield assembly, including solar arrays (Sect. 3.2). Credit: ESA, ATG Medialab.