Page 46 - Apollo Moonships

44 On bOard apOllO mOOnships
GUIDANCE AND CONTROL SYSTEMS
The Apollo mother ship was controlled and guided into space by two major units: the Stabilization and Control System (SCS) and the Primary Guidance and Navigation Control System (PGNCS). The SCS was designed to monitor the orientation
of the spaceship, maintain its attitude, and provide thrust vector control, changing the firing direction of the service propulsion engine. The system included several components
to automatically hold the spacecraft’s rotation and velocity but also to adjust them manually, for example, using the rotation and translation hand controllers mounted on the left and right armrests of the spaceship commander couch. The SCS could be operated in various attitude modes, such as automatic control, proportional rate, minimum impulse, acceleration command,
and direct mode. Additionally, the thrust vector control could be configured to operate automatically or manually. On the other hand, the PGNCS gave astronauts the capability to determine the spacecraft’s trajectory and to follow a predetermined course. It was comprised by three main components: the inertial subsystem (ISS), which sensed changes in the spacecraft velocity and attitude to generate steering commands; the optical subsystem (OSS), composed by a sextant and a scanning telescope used to take accurate navigational measurements using a reference star and lunar or Earth landmarks; and the computer subsystem (CSS), which processed the data from
the ISS and OSS to determine the spacecraft trajectory and calculate the corrections to maintain course.
SCS AND PGNCS MAIN COMPONENTS
1
2 3
Translation hand controller (SCS)
Flight control panel (SCS) Rotation hand controller (SCS)
4 Guidance and navigation station (PGNCS)
5 Space sextant (PGNCS)
6 Scanning telescope (PGNCS)
7 Control panel (PGNCS)
8 Computer subsystem main
panel keyboard (PGNCS)
ROTATION HAND CONTROLLER (SCS)
2 1
3
Left locking handle
–Y –X
TRANSLATION HAND CONTROLLER (SCS)
17° 17°
–Z –Y
–Z
–Y
+X +Y
+Y
4 5
6
7
8
Right locking handle
Hardstops each 17° in either direction
–X
+X
+Y +Z