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.
Mass Budget
| 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 |
Power and Energy
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: 1 September 2019
