Science Instrument Control and Data Handling Unit
The Science Instrument Control and Data Handling (SI C&DH) unit keeps all science instrument systems synchronized. It works with the on-board Data Management Unit (DMU) to process, format, temporarily store on the data recorders, or transmit to the ground all science and engineering data created by the instruments.
The SI C&DH is mounted on the door of Bay 10 in the equipment section of the Support Systems Module (SSM). The equipment section is a ring of storage bays located just behind the two high gain antennas (where Hubble's diameter increases from 3 m to 4.2 m).
The opened door of Bay 10 is seen in this image, showing the main components of the SI C&DH which are attached to an orbital replacement unit (ORU) tray:
|upper left and right:
|2× 4 memory modules
|lower left and right:
|2× control unit/science data formatter +
2× remote interface unit
|2 central processor modules +
2 standard interfaces
|power control unit
For redundancy these components actually form 2 identical sets, referred to as side A and side B.
The white bar in the middle of the SI C&DH unit components is the extravehicular activity handle, for holding the ORU tray and the SI C&DH unit when it is not attached to the door.