Reacting chemicals supplied continuously as needed to change.

(TYPICAL) ORBITER FLIGHT DECK * MANUAL CONTROLS * INDICATORS e DISPLAYS BACKUP OPTICAL UNIT NOSE AIR DATA TRANSDUCER ASSEMBLY RCS JET ORIVER (FORWARD) * GENERAL-PURPOSE COMPUTERS Figure 4-15.— Orbiter guidance, navigation, and control 2. Two magnetic-tape mass memories for large- volume bulk storage 3. Time-shared serial-digital data buses are used; during minimum power.