The space shuttle vehicle
relies on computerized control and monitoring for successful performance.
The data processing system, through the use of various hardware
components and its self-contained computer programming (software),
provides the vehicle with this monitoring and control.
The DPS hardware consists of five general-purpose computers for
computation and control, two magnetic tape mass memory units for
large-volume bulk storage, a time-shared computer data bus network
consisting of serial digital data buses (essentially party lines)
to accommodate the data traffic between the GPCs and space shuttle
vehicle systems, 19 orbiter and four solid rocket booster multiplexers/demultiplexers
to convert and format data from the various vehicle systems, three
space shuttle main engine interface units to command the SSMEs,
four multifunction CRT display systems used by the flight crew
to monitor and control the vehicle and payload systems, two data
bus isolation amplifiers to interface with the ground support
equipment/launch processing system and the solid rocket boosters,
two master events controllers, and a master timing unit.
The software stored in and executed by the GPCs is the most sophisticated
and complex set of programs ever developed for aero space use.
The programs are written to accommodate almost every aspect of
space shuttle operations, including orbiter checkout at Rockwell's
Palmdale, Calif., assembly facility; space shuttle vehicle prelaunch
and final countdown for launch; turnaround activities at the Kennedy
Space Center and eventually Vandenberg Air Force Base; control
and monitoring during launch ascent, on-orbit activities, entry
and landing; and aborts or other contingency mission phases. A
multicomputer mode is used for the critical phases of the mission,
such as launch, ascent, entry, landing and aborts.
Some of the DPS functions are as follows: support the guidance,
navigation and control of the vehicle, including calculations
of trajectories, SSME thrusting data and vehicle attitude control
data; process vehicle data for the flight crew and for transmission
to the ground and allow ground control of some vehicle systems
via transmitted commands; check data transmission errors and crew
control input errors; support annunciation of vehicle system failures
and out-of-tolerance system conditions; support payloads with
flight crew/software interface for activation, deployment, deactivation
and retrieval; process rendezvous, tracking and data transmissions
between payloads and the ground; and monitor and control vehicle