All communication with the Gaia spacecraft is done using the X-band.

For telemetry and telecommand, low gain antenna up- and down-links with a few kbps capacity and an omni-directional coverage are employed.

The science telemetry X-band down-link is based on a set of electronically-scanned phased array antennae accommodated on the service module bottom panel. This high gain antenna is used during each ground station visibility period of about 8 hours per day.

Nominal spacecraft control during the routine mission phase will be done off line - contacts between the Mission Control Centre at ESOC and the spacecraft, except for collecting payload and housekeeping telemetry, will primarily be used for pre-programming of the autonomous operations functions on the spacecraft (up-link of mission timeline), and for science data collection.

	Attitude and Orbit Control
	Data Handling