ESA Science & Technology: Spacecraft

Spacecraft

The Gaia spacecraft is comprised of three major functional modules:

The Payload Module containing the optical instrument and all electronics required to manage its operation and process its raw data. For this purpose the Payload Module includes the Video Processing Unit, the Clock Distribution Unit (housing the atomic clock references) and the Payload Data Handling Unit in charge of data storage between two downlink sessions
The Mechanical Service Module made of all mechanical, structural and thermal elements supporting the instrument and the spacecraft electronics. In addition, the mechanical SVM comprises:
- Micro-Propulsion system
- Deployable sunshield
- Payload thermal tent
- Solar arrays
- Harness
The Electrical Service Module offers support functions to the Gaia payload and spacecraft for pointing, electrical power control and distribution, central data management and Radio communications with the Earth

The spacecraft's micropropulsion system for the fine attitude control will be proportional cold gas.

Component	Estimated Mass
Payload Module	524 kg
Service Module	868 kg
Spacecraft dry mass total	1392 kg
Micro propulsion propellant	59 kg
Propellant	237 kg
Launch mass	1934 kg
Launch Vehicle Adapter	95 kg
Total launch mass	2029 kg

The 12.8 m² triple-junction solar array provides up to 1910 W under end-of-life worst case conditions.

Component	Power
RF Communications	326 W
Data Management and AOCS	103 W
Electrical power & solar array	117 W
Propulsion (biliquid & micropropulsion)	24 W
Thermal control	0 W
SREM	2.6 W
Payload module	627 W
Total required power	1561 W
Solar array capability	1910 W

Last Update: 17 Mar 2013