CM and LM Guidance and Navigation Equipment

CM and LM Guidance and Navigation Equipment

The Apollo Command Module Guidance and Navigation system is composed of three basic subsystems: Inertial, Optical and Computer.

  1. The inertial guidance subsystem is composed of inertial measurment unit (IMU) and associated equipment. This subsystem performs three major functions: (A) Measures changes in spacecraft attitude; (B) Measures spacecraft velocity due to thrust; and (C) Assists in generating steering signals.
  2. The optical navigation subsystem is composed of a space sextant and a scanning telescope. Sightings on celestial bodies and landmarks on the moon and earth are used by the computer subsystem to determine the spacecraft's position and velocity and to align the inertial reference within the IMU.
  3. Then command module computer (CMC) provides five major functions: (A) Calculators steering signals and engine discretes necessary to keep the spacecraft on the required trajectory; (B) Positions the stable member in the IMU to a coordinate system defined by precise optical measurements; (C) Positions the optical unit to celestial objects: (D) Conducts limited malfunction isolation of the G&N system by monitoring the level and rate of system signals; and (E) Supplies pertinent spacecraft condition information to the display and control panel.

LM Guidance and Navigation Equipment

  1. Inertial measurment unit (IMU) and associated equipment performs three major functions: (A) Measures changes in LM attitude; (B) Measures spacecraft velocity due to thrust; and (C) Assists in generating steering signals.
  2. Alignment Optical Telescope (AOT) - Provides star sighting data which is manually inserted into the LM Guidance Computer for establishing the inertial reference.
  3. LM Guidance Computer (LGC) - Performs four major functions; (A) Calculates steering signals and engine discretes necessary to keep the LM on the required trajectory, (B) Positions the stable member in the IMU to a coordinate system defined by precise optical measurements, by monitoring the level and rate of system signals and (D) Supplies pertinent LM condition information to the display and control panels.
  4. Display and Keyboard (DSKY) - Provides a two-way communication link between the operator and the LGC and the following functions may be performed: (A) Loading of data into the LGC and (B) Display of data and system configuration to the operator.
  5. Coupling Data Unit (CDU) - The CDU, an all electronic device, is used as an inteface element between the following; (A) The inertial subsystem and computer subsystem and (B) The computer subsystem and the controls. This unit functions primarily as an analog to digital or digital to analog converter.

Apollo 11 Mission Description

  1. Fourth Manned Saturn V Mission
  2. First Lunar Landing and Return Mission
  3. Planned duration up to 11 days with Pacific Ocean Recovery
  4. Booster- Saturn V Booster #506
  5. Spacecraft - CSM #107 and Lunar Module #5
  6. Block II G&N System #210 - LM G&N System #609

Event Time
HR:MIN:SEC G.E.T. 		Data Summary
Earth Orbit Insertion 0:11:43 Latitude, DEG N: 32.8
Longitude, DEG W: -54.2
Inclination, DEG: 32.7
Translunar Injecion 2:44:26 Burn Time, SEC: 320.0
Plane Change, DEG: -1.18
SPS Evasive Maneuver 4:39:44 Altitude, N. Mi. -- 16,625.7
Delta V, FPS -- 19.7
Burn duration, SEC -- 2.9
Propellant Used, LB -- 187.9
Lunar Orbit Insertion 75:54:28 Mass at Ignition, LB - 95,013.8
Burn Time, SEC -- 359.0
Propellant Used, LB -- 23,815.5
Inclination of LPO, DEG - 1.3
Delta V, FPS -- 2,924.4
LOI-2 80.09.29 Mass at Ignition, LB -- 71,148.9
Burn Duration, SEC -- 16.4
Propellant Used, LB -- 966.0
Delta V, FPS -- 157.8
LM Separation (Minifootball) 100:39 Mass at Ignition, LB -- 36,276.2
Burn Time, SEC -- 8.0
Propellant Used, LB -- 12.3
Delta V, FPS -- 2.5
DOI 101:38:48 Ignition Longitude, DEG -- 341.4
Delta V, FPS -- 71.4
PDI 102:35:13 Ignition Longitude, DEG -- 39.6
Delta V, FPS -- 6,766
Burn Duration, SEC -- 718.0
Propellant, Used, LB -- 16,748.1
Ascent 124:23:26 Sun Elevation at Site, DEG -- 9.85
Propellant Used, LB -- 4,989.9
Delta V, FPS -- 6,060.0
Burn Duration, SEC -- 438.0
Lunar Orbit Plane Change 125:50:28 Mass at Ignition, LB -- 36,263.9
Burn Time, SEC -- 0.4
Propellant Used, LB -- 59.0
Plane Change, DEG -- +0.2
CSI 125:21:19 Ignition Longitude, DEG -- -149.2
Delta V, FPS -- 49.5
Burn Duration, SEC -- 45.0
CDH 126:19:37 Ignition Longitude, DEG -- 30.1
Delta V, FPS -- 4.3
Burn Duration, SEC -- 1.9
TPI 126:58:08 Ignition Longitude, DEG -- -89.2
Delta V, FPS -- 24.8
Burn Duration, SEC -- 22.4
Docking 128:00
CSM Separation Maneuver
Following LM Jettison 		131:53:05 Mass at Ignition, LB -- 36,370.9
Burn Time, SEC -- 3.2
Propellant Used, LB -- 5.0
Delta V, FPS -- 1.0
TransEarth Injection 135:24:34 Mass at Ignition, LB -- 36,268.6
Burn Time, SEC -- 149.0
Plane Change, DEG -- +4.80
Propellant Used, LB -- 9,712.0
Delta V, FPS -- 3292.7
Entry Interface 195:03:27 Velocity, FPS -- 36,160.6
Flight-Path Angle, DEG -- -6.50
Latitude, DEG -- -03.5
Longitude, DEG -- 171.4
Time From TLI, HR:MIN -- 59.52
Splashdown 195:17:22 Latitude, DEG -- +10.65
Longitude, DEG -- -172.5

Time refers to Ground Elapsed Time (G.E.T) of ignition for burns.

Apollo 11 Mission Events Summary

G.E.T
HR:MIN:SEC 		EVENT
LAUNCH-0932 EDT, 0832 CDT
11:43 Earth Orbit Insertion
50:00 P52 REFS
1:32:00 Update State Vector
2:12:00 GDC Align to IMU
2:44:26 TLI B.T. 5 MIN 20 SEC
Delta V 10,451 FPS
2:52:00 P00 CMC Idling
3:15:00 CSM S-IVB SEP
3:25:00 DOCKING
4:09:45 LM EJECTION BT 3.0 SEC
4:25:00 P40
4:39:45 EVASIVE MNVR B.T. 2.8 SEC
DELTA V 19.7 FPS
5:38:00 P52 REFS
6:00:00 P23 CISLUNAR NAV & OPTICS CAL
10:10:00 UPDATE STATE VECTOR
10:43:00 P52 REFS
11:15:00 P40/41
11:45:00 MCC1
12:05:00 P52 REFS
24:18:00 P52 REFS
24:30:00 P23 CISLUNAR NAV
26:13:00 P40/41
26:45:00 MCC2
53:10:00 P52 REFS
53:27:00 P40/41
53:55:00 MCC3
56:15:00 LMP IVT TO LM
56:25:00 CDR IVT TO LM
57:48:00 LMP IVT TO CSM
57:53:00 CDR IVT TO CSM
68:32:00 STATE VECTOR UPDATE
70:10:10 P52 PREF
70:25:00 P40/41
70:55:00 MCC4
73:40:00 P52 REFS
74:05:00 MNVR TO BURN ATTITUDE
75:25:00 P40
75:54:28 LOI1 B.T. 6 MIN
DELTA V 29.24 FPS
59.2 x 169.8 ORBIT
79:30:00 PIPA BIAS CHK.
79:33:00 MNVR TO LOI2 BURN ATTITUDE
79:38:00 P40
80:09:30 LOI2 B.T. 16.4 SEC
DELTA V 157.8 FPS
53.6 x 65.5 ORBIT
81:20:00 P52 REFS
81:35:00 PREPARE FOR LM EGRESS
81:45:00 LMP IVT TO LM
82:25:00 P22
83:42:00 LMP IVT TO CSM
95:52:00 LMP IVT TO LM
96:53:00 CDR IVT TO LM
96:58:00 P52 REFS
98:35:00 P22
99:57:00 MNVR TO UNDOCK ATTITUDE
100:15:00 UNDOCK
100:31:00 P41
100:39:50 CSM SEP B.T. 8 SEC
DELTA V 2.5 FPS
55.6 x 63.1 ORBIT
100:49:00 P20
101:03:00 P52 REFS
101:30:00 P20 SEXTANT TRACK LM
102:32:00 P00 MANUAL ATTITUDE
103:36:00 P22
104:45:00 LM TRACKING
105:00:00 P52 REFS
106:58:00 P40
107:05:33 SPS, PLANE CHANGE
107:27:00 P52 REFS
114:35:00 VISUAL TRACKING LM (COAS)
124:10:00 MNVR TO SUPPORT LM LO
124:40:00 P52 REFS
125:27:00 P20 (SEXTANT TRACK LM)
126:15:00 P41 CDH BACK-UP
128:00:00 DOCKING
130:05:00 CDR IVT TO CSM
130:43:00 LMP IVT TO CSM
131:53:05 LM JETTISON B.T. 3.1 SEC
DELTA V 1 FPS
58.5 x 59.4 ORBIT
132:00:00 MNVR TO TEI BURN ATTITUDE
134:42:00 P52 REFS
135:02 P40
135:24:34 TEI BT 2 MIN 29 SEC
DELTA V 3292.7 FPS
135:47:00 P52 REFS
136:00:00 P23 (5 SETS)
147:00:00 P23 (5 SETS)
149:25:00 P52 REFS
150:00:00 P40/41
150:24:00 MCC5
154:30:00 P23 (3 SETS)
158:00:00 P23 (5 SETS)
171:10:00 P52 REFS
171:32:00 P40/41
172:00:00 MCC6
191:08:00 P52 REFS
191:30:00 P40/41
192:06:00 MCC7
193:40:00 P52 REFS
194:20:00 P27
194:51:00 CM/SM SEP
195:03:27 ENTRY INTERFACE 400,000 FEET
195:10:41 GUIDANCE TERMINATION
195:11:39 DROGUE CHUTE DEPLOY
195:12:27 MAIN DEPLOY
195:17:22 SPLASHDOWN

CM Computer Programs

Phase Program
Number 		Program Title
Prelaunch
and
Service 		00 CMC Idling
01 Prelaunch or Service-Initialization
02 Prelaunch or Service-Gyro Compassing
03 Prelaunch or Service-Optical Verification of Gyro Compassing
06 GNCS Power Down
07 Systems Test
Boost 11 Earth Orbit Insertion Monitor (EOI)
17 Transfer Phase Initialization Search (TPI)
Coast 20 Rendezvous Navigation
21 Ground Track Determination
22 Orbital Navigation
23 Cislunar Midcourse Navigation
27 CMC Update
Pre-
Thrusting 		30 External Delta V
31 Lambert Aimpoint Maneuver
32 Co-elliptic Sequence Initiation
33 Constant Delta Altitude
34 Transfer Phase Initiation (TPI)
35 Transfer Phase (Midcourse)
37 Return to Earth (RTE)
38 Stable Orbit Rendezvous (SOR)
39 Stable Orbit Midcourse (SOM)
Thrusting 40 SPS
41 RCS
47 Thrust Monitor
Alignment 51 IMU Orientation Determination
52 IMU Realign
53 Back-up IMU Orientation Determination
54 Back-up IMU Realign
Entry 61 Entry-Maneuver to CM/SM Separation Attitude
62 Entry-CM/SM Separation and Pre-entry Manuver
63 Entry Initialization
64 Entry-Post 0.05G
65 Entry-UP Control
66 Entry-Ballistic
67 Entry-Final Phase
Abort 72 LM Co-Elliptic Sequence Initiation (CSI) Targeting
73 LM Constant Delta Altitude (CDH) Targeting
74 LM Transfer Phase Initiation (TPI) Targeting
75 LM Transfer Phase (MIDCOURSE) Targeting
76 LM Target Delta V
77 LM TPI Search
78 LM SOR Targeting
79 LM SOM Targeting

Copyright 1997, 1998, 1999 by John Duncan
Comments and questions welcome. All photographs contained on these pages are the author's, unless otherwise noted. No unauthorized reproduction without permission.

Last update: January 1, 1999