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Text and Graphics System

The text and graphics system is used when there is an operational TDRSS. The TAGS consists of a facsimile scanner on the ground that sends text and graphics through the Ku-band communications system to the text and graphics hard copier in the orbiter. The interim teleprinter operates via the S-band PM system when the TDRSS is not operational. The hard copier installed on a dual cold plate in avionics bay 3 of the crew compartment middeck provides an on-orbit capability to transmit text material, maps, schematics, maneuver pads, general messages, crew procedures, trajectory and photographs to the orbiter through the two-way Ku-band link using the TDRSS. It is a high-resolution facsimile system that scans text or graphics and converts the analog scan data into serial digital data. Transmission time for an 8.5- by 11-inch page can vary from approximately one minute to 16 minutes, depending on the hard copy resolution desired.

The text and graphics hard copier operates by mechanically feeding paper over a fiber-optic CRT and then through a heater-developer. The paper then is cut and stored in a tray, accessible to the flight crew. A maximum of 200 8.5- by 11-inch sheets are stored. The status of the hard copier is indicated by front panel lights and downlink telemetry.

The hard copier can be powered from the ground or by the crew. The ground can power up the system when the Ku-band control switch is in the command position. When this switch is in the panel position, the crew can power up the system.

Uplink operations are controlled by the Mission Control Center in Houston. Mission Control powers up the hard copier and then sends the message. In the onboard system, light-sensitive paper is exposed, cut and developed. The message is then sent to the paper tray, where it is retrieved by the flight crew.


Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 04/07/2002
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