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
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.
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.