Power & Thermal Subsystem

Telemetry, Tracking and Command

The spacecraft TTC equipment is connected directly to the Main Bus via current limiters. The two receivers are operated in hot redundancy, and are wired such that both cannot be switched off at once. Each receiver consumes 3.5W. The Decoders are continually powered and cannot be switched; they each consume 3.3W in standby and an additional 2.7W when processing an uplink signal.

There are two X-band and two S-band transmitters on the spacecraft. A single X-band transmitter is normally on for the transmission of spacecraft data to the Earth; this consumes 7.6W before amplification. The S-band transmitters are not used for routine data transmission during this part of the mission - they each take approximately 35W when transmitting.

For a description of the full TTC subsystem, see the section on the TTC subsystem