2018 - Vol. 25 - No. 3 spacehistory101.com

THE HISTORY OF SPACEFLIGHT QUARTERLY

A HISTORY OF SOVIET/RUSSIAN MISSILE EARLY WARNING SATELLITES - PART II

DEVICES TO CONTROL UNMANNED FLIGHTS

AN INTERVIEW WITH HAROLD B. FINGER: NUCLEAR INVESTIGATIONS

REAL SPACE MODELING

GEORGE ABBEY: THE MAKER Contents Volume 25 • Number 3 2018 www.spacehistory101.com

FEATURES BOOK REVIEWS 71 Chasing : Inside the Epic 3 A History of Soviet/Russian Missile Early Warning First Mission to Pluto Satellites—Part II Book by Alan Stern and David Grinspoon By Bart Hendrickx Review by Michael J. Neufeld

27 Devices to Control Unmanned Apollo Flights 72 Space Science and the Arab World: By Edgar Durbin , Observatories and Nationalism in the Middle East ORAL HISTORY Edited by Jӧrg Matthias Determann Review by Christopher Gainor 39 An Interview with Harold B. Finger: Nuclear Investigations Interview by Kevin M. Rusnak FRONT COVER CAPTION

An image from a September 1964 Aerojet report BIOGRAPHY / BOOK REVIEW showing the locations of test instruments overlaid on top of a graph showing the fast neutron and gamma 58 George Abbey: ray radiation flux around the NERVA nuclear engine at power. The Astronaut Maker—How One Mysterious Engineer Ran for a Generation Please note that two words (GAGE and etimated) are Book by Michael Cassutt misspelled in the original image. Profile and review by Glen E. Swanson Credit: Aerojet

ARCHIVES & MUSEUMS

66 Real Space Modeling By Keith J. Scala

Images Courtesy: Heritage Auctions F EATURE DEVICES TO CONTROL UNMANNED APOLLO FLIGHTS

By Edgar Durbin nauts for these tests, NASA devel- The third device controlled the oped three devices. Lunar Module (LM) during Apollos Introduction The first was needed for mis- 5, 9, and 10. Many components Several Apollo missions were sion AS-201, the only Apollo space- were developed for the Apollo pro- flown without crews to test space- craft launched on a rocket gram, including the spacecraft, craft hardware and software to avoid that did not carry a Primary launch vehicle, mission control, risk to astronauts. These missions Guidance, Navigation, and Control tracking network, and other ele- tested equipment and rehearsed System (PGNCS). ments. Table 1 lists Apollo launches maneuvers that would be performed The second was used on mis- using Saturn IB and rock- under astronaut control during oper- sions AS-202 and Apollos 4 and 6. ets. Shaded area denotes missions ational flights. To replace the astro- These four missions tested carrying the control devices dis- Command Module (CM) reentry. cussed in this article. MISSION LAUNCH VEHICLE RESULT AS-201 26-Feb-66 Saturn IB - CSM Sub-orbital unmanned CM reentry, SM engine test Sub-orbital unmanned CM reentry, SM engine test with AS-202 25-Aug-66 Saturn IB - CSM Primary Guidance and Navigation System (PGNCS) AS-203 5-Jul-66 Saturn IB Earth orbit of S-IVB stage, S-IVB restart 27-Jan-67 Saturn IB - CSM Fire in CM on launch pad, killed crew First Saturn V flight, unmanned CSM Earth orbit, test of 9-Nov-67 Saturn V - CSM - LTA S-IVB restart, CM reentry Unmanned LM Earth orbit, test of descent and ascent 22-Jan-68 Saturn IB - LM engines S-IVB failed to restart, TLI demo aborted, unmanned Apollo 6 4-Apr-68 Saturn V - CSM - LTA CM reentry 11-Oct-68 Saturn IB - CSM Manned CM Earth orbit and reentry 21-Dec-68 Saturn V - CSM Manned CSM lunar orbit Manned CSM and LM Earth orbit, EVA, separation and 3-Mar-69 Saturn V - CSM - LM rendezvous 18-May-69 Saturn V - CSM - LM Manned lunar orbit and partial lunar descent 16-Jul-69 Saturn V - CSM - LM Manned lunar landing, EVA (Extravehicular Activity) 14-Nov-69 Saturn V - CSM - LM Precision manned lunar landing near 3, EVA SM oxygen tank explosion aborted mission, shortened 11-Apr-70 Saturn V - CSM - LM to translunar return 31-Jan-71 Saturn V - CSM - LM Manned lunar landing, EVA Manned lunar landing, exploration in Lunar Roving 26-Jul-71 Saturn V - CSM - LM Vehicle (LRV), lunar subsatellite launch, EVA Manned lunar landing, exploration in LRV, lunar sub- 16-Apr-72 Saturn V - CSM - LM satellite launch, EVA 7-Dec-72 Saturn V - CSM - LM Manned lunar landing, exploration in LRV, EVA

Table 1. Saturn IB and V launches in the . The launch vehicles for the missions discussed in this article are shown in Figure 1.

Q U E S T 25:3 2018 27 www.spacehistory101.com Figure 2. Command Service Figure 1. Launch vehicles for missions Module (CSM).3 discussed in this article.1

Mission Vehicles and (CSM). Three of the four Reaction The Launch Escape System (LES) at the top of the Control System (RCS) clusters of attached to the vehicles carrying a CM could pull the astronauts away SM that determined CSM attitude can be seen. The bell- from a malfunctioning Saturn early in the launch. The shaped nozzle of the Service Propulsion System (SPS) LES was jettisoned soon after the first stage had shut is at the bottom of the figure. High-pres- down and the second stage ignited. The Spacecraft sure forced SPS propellants2 out of their tanks Lunar Module Adapter (SLA) was designed to house the into the combustion chamber. However, in the weight- LM, but was empty on AS-201 and AS-202. Apollos 4 less condition of orbital and coasting flight, liquids can and 6 carried LM Test Articles (LTA), test vehicles that drift away from the outlets leading to the combustion did not leave the SLA. Apollos 5, 9, and 10 carried LMs chamber. To prevent helium from entering the combus- that maneuvered after separation from the SLA and the tion chamber, it was necessary to settle the fuels by CM. The Instrument Unit (IU) contained the navigation, “ullage” burns of the RCS to force the liquids to the out- guidance, control, and communications systems that lets before opening the fuel valves. controlled the mission up to separation of the spacecraft The CM appears in Figure 3. The pitch, roll, and from the S-IVB. yaw RCS engines gave full control of CM attitude after Figure 2 shows the combined Command Module separation from the Service Module. Q U E S T 25:3 2018 28 www.spacehistory101.com First Device: Automated Control System Apollo-Saturn 201 (AS-201) had many objectives. The Apollo Program Flight Summary Report list of AS-201’s goals cov- ers three-and-a-half pages.5 It was the first— Saturn IB flight; Mission controlled by the Mission Control Center (MCC) in the Manned Spacecraft Center (MSC) in Houston; Flight of the Block I Command Module (CM) and Service Module (SM); Start and restart of the Service Propulsion System (SPS), the main rocket carried by the SM; Recovery of the CM after reentry

Figure 3. Command Module (CM).4

through the atmosphere. The non-orbital flight lasted 37 minutes, starting at Cape Figure 4. Trajectory and Kennedy and ending with of events of AS-201.12 the CM in the Atlantic 8,476 km away. See Figure 4. (The legend for Figure 4 and the list of major events are given in Table 2.) The Saturn IB vehicle had two pow- ered stages: the S-IB first stage and the S- IVB second stage. The S-IB lifted the mis- LABEL EVENT TIME (sec) VEHICLE sion to 58.9 km altitude 62.0 km downrange in 2.44 1 Launch 0.0 S-IB minutes.6 It separated from the S-IVB, which fired its Start pitch and roll 11.20 S-IB single gimbaled J-1 engine for 7.56 minutes7 and shut Roll stop 20.55 S-IB Pitch stop 134.39 S-IB down at 250.5 km altitude 1592.3 km downrange. 2 S-IB cutoff 146.9 S-IB (The step in the trajectory during the early part of the S-IB/S-IVB separation 147.76 S-IVB S-IVB firing was due to the difference between the S-IVB ignition 149.35 S-IVB LES tower jettison 172.64 S-IVB thrust of the S-IB and the S-IVB. At the end of the S- 3 S-IVB cutoff 602.9 S-IVB IB flight the acceleration due to the eight H-1 engines S-IVB pitch down start 613.95 S-IVB of the S-IB (thrust/mass) was 41.6 m/sec2, whereas at 4 S-IVB pitch down end 728.3 S-IVB 5 S-IVB/CSM separate 844.9 S-IVB S-IVB ignition its single J-1 engine produced RCS +X translation 1 on 846.7 CSM thrust/mass of only 7.25 m/sec2)8 As the S-IVB/CSM RCS +X translation 1 off 864.6 CSM vehicle continued to coast, the Instrument Unit con- 6 CSM apogee 1020.0 CSM 9 RCS +X translation 2 on 1181.2 CSM trolled a pitch down of 109.15 degrees to put the 7 SPS burn 1 start 1211.2 CSM CSM in the attitude at which the Service Module RCS +X translation 2 off 1212.2 CSM would later fire its Service Propulsion System 8 SPS burn 1 end 1395.2 CSM 10 RCS +X translation 3 on 1395.7 CSM (SPS). The CSM separated from the S IVB and 9 SPS burn 2 start 1410.7 CSM fired the RCS for 18 sec in the +X direction (toward RCS +X translation 3 off 1420.7 CSM the pointed end of the CM) to increase their separa- 10 SPS burn 2 end 1420.7 CSM 11 C/SM separate 1455.0 CSM tion. The CSM coasted through its apogee of 492.0 12 Blackout start 1580.0 CM km11 and ignited the SPS for three minutes. The SPS 13 Blackout end 1695.0 CM was turned off and then restarted for a second, short 14 Drogue parachute deployed 1855.4 CM 15 Main parachute deployed 1908.4 CM burn of ten seconds. Two RCS +X translation maneu- 16 Splashdown 2239.7 CM vers settled the SPS propellants. Table 2. Major events of Q U E S T 25:3 2018 AS-201 mission.13 29 www.spacehistory101.com The Command Module for CM/SM separation; CM RCS; The Stabilization Control AS-201 carried an automated con- Parachute deployment; Reception Subsystem (SCS) included two trol system to perform functions of uplinked commands. Figure 5 gyro assemblies with three body- that in an operational spacecraft shows the system block diagram. mounted gyros that sensed space- an astronaut would make by inputs The components on the right side craft attitude.14 The automated to the PGNCS. The device con- of this diagram, outside the dashed control system had an Attitude trolled the CSM Reaction Control box defining the automated control Reference System (ARS) that was System (RCS); Service Propulsion system, were part of the Block 1 backup to the SCS gyros. System (SPS) start and stop; Command Module.

Figure 5. AS-201 automated control system block diagram and interfaces.15

16 When the S-IVB cams to open and close 22 switches Control from the ground. Before Instrument Unit sensed separation at times determined by the shape of the SPS fired, its gimbals were set of the spacecraft, it signaled the cams. Changes to the program to point its thrust through the vehi- Automated Command Control could be made up to two weeks cle center of mass, which changed (ACC) to start the Sequential before integrated testing began at during a mission as fuel burned off. Timer. This timer, developed for KSC, by cutting new cams. Without this preliminary setting, the Agena B, controlled 22 events Another timer for abort events when the SPS turned on, excessive for missions lasting up to 2,498 could store 14 times. The selection RCS fuel would be used to keep the seconds. The normal events are of abort or normal program was vehicle accelerating in the correct listed in Table 3. The timer used a signaled by the Instrument Unit direction. motor-driven mechanism to rotate (before separation) or by Mission

Q U E S T 25:3 2018 30 www.spacehistory101.com EVENT TIME COMMENT 1 Start normal timer. 663.1 IU signal to start separation sequence. 2 Tape recorders OFF. 665.2 S-IVB/spacecraft separation signal ON. 3 843.2 Uncage SC gyros. S-IVB/spacecraft separation signal OFF. 4 846.7 First RCS burn, of 18 sec. Plus-X translation ON. 5 Plus-X translation OFF. 864.6 Second RCS burn starts 5 min (316.6 sec) 6 Plus-X translation ON. First gimbal position set. 1181.2 after the first, to settle SPS fuel in tanks (ullage burn). 7 Primary SPS gimbal motors ON. 1196.1 Secondary SPS gimbal motors ON. Remove primary 8 1197.1 motors ON command. 9 Remove secondary motors ON command. 1197.1 10 Arm SPS thrust solenoids. SPS thrust ON. 1211.2 11 Tape recorders ON. 1321.9 12 Plus-X translation OFF. SPS thrust OFF. 1395.2 SPS and RCS burns end after 3 min (184 sec). 13 SPS thrust ON (secondary source on SPS control). 1395.4 Plus-X translation ON. SPS thrust OFF. 14 1395.7 Third RCS burn, to settle SPS fuels. Second gimbal position set. 15 SPS thrust ON. 1410.7 Second SPS burn, for 10 sec. 16 SPS thrust OFF. Plus-X translation OFF. 1420.7 17 Pitch rate (-5 deg/sec) ON. 1424.1 The CSM pitches over 90 deg in 18 sec. 18 Pitch rate (-5 deg/sec) OFF. 1442.1 19 CM/SM separation start. SCS entry mode ON. 1454.2 8 sec later the CM separates from the SM. 20 Pitch rate (-5 deg/sec) ON. 1462.6 The CM pitches over 82.5 deg in 16.5 sec. 21 Pitch rate (-5 deg/sec) OFF. Roll rate (+5 deg/sec) ON. 1479.1 The CM rolls 180 deg in 36 sec. Ross rate (+5 deg/sec) OFF. Arm 0.05g backup. ELS 22 1515.1 activate.

Table 3. Events controlled by sequence timer for normal mission.17

The block diagram of a fully oper- in Figure 7 and Figure 8. transmitted through the PGNCS ational CSM with astronaut and Interfaces to the SCS for these interface. The +X translation com- PGNCS appears in Figure 6. The devices and the others missing mands could use the translation dashed box indicates components from AS-201 were used by the control interface. Pitch and roll missing from AS-201. Two of automated control system. commands might pass through the these astronaut controls are shown Commands to the SPS could be rotation control interface.

Q U E S T 25:3 2018 31 www.spacehistory101.com Figure 7. Rotation control, aka control stick steering (CSS).19

Figure 8. Translation control.20

Figure 6. Interfaces available to the automated control system.18

Second Device: Mission Control Programmer Mission AS-202 was another suborbital test of CM reentry launched by a Saturn IB. The major dif- ference from AS-201 was the presence of the PGNCS. It oriented the CSM for SPS firing after separation from the S-IVB, while for AS-201 the IU set the CSM attitude before separation. The PGNCS cued RCS and SPS firing on AS-202, whereas these events occurred on AS-201 at predetermined times. Also, the PGNCS controlled CM attitude during entry to achieve a one- skip trajectory. See Figure 9.

Figure 9 Mission AS-202 Command Module altitude during entry.21

Q U E S T 25:3 2018 32 www.spacehistory101.com Apollo 4 was the first flight of a much higher than earlier missions. end of the first stage (S-IC) firing, Saturn V launch vehicle, and put a This produced a higher entry veloc- large 5 Hz oscillations exceeded the CSM and a LM Test Article into ity and a heating rate similar to the spacecraft design criteria, causing Earth orbit. The orbital mission maximum conditions during a lunar pieces of the SLA to shake loose allowed a period of “cold soak” return.22 from the vehicle. which achieved the thermal condi- Although the mission plan for The Mission Control tions of an operational mission. The the Apollo 6 mission was similar to Programmer (MCP) took the place CM was oriented for four-and-one that of Apollo 4, several failures of an astronaut on missions AS-202, half hours with the sunlight perpen- caused Mission Control to order an Apollo 4, and Apollo 6.23 It con- dicular to the CM hatch, so that a alternate program. The S-IVB did sisted of three components, shown thermal gradient was created across not start for its scheduled TLI burn in Figure 10: the Attitude and the surface of the . Other so the SPS was used instead to Deceleration Sensor (ADS), the changes from AS-201 and AS-202 achieve the planned apogee (12,000 Spacecraft Command Controller were the start and restart of the SPS n mi). The MCC cancelled the sec- (SCC), and the Ground Command without ullage burns of the RCS, ond burn of the SPS due to the extra Controller (GCC). and a simulated Translunar use of fuel to make up for the S- Injection (TLI) burn by the S-IVB IVB failure, and the entry velocity that raised the CSM to an altitude was lower than Apollo 4. Near the The ADS contained accelerometers to back up accelerom- eters in the PGNCS. Several events were triggered by the start of entry, which occurred at approximately 400,000 feet altitude, when decelera- tion due to the atmosphere reached 0.05 g. This was sensed by the PGNCS and the ADS. If the PGNCS failed the ADS also provided backup measurement of spacecraft attitude. The MCP accepted keying com- mands from four sources and sent sequence commands to spacecraft components. The SCC took inputs from three sources, and the GCC Figure 10. The three components of the Mission Control Programmer received inputs from the Mission installed in place of CM crew couches.24 Control Center. For AS-202 the SCC received the eleven key commands NUMBER OF SOURCE EXAMPLES from the PGNCS listed in Table 4. COMMANDS Two of these commands were deleted Flight director attitude indicator alignment / Gimbal for Apollos 4 and 6. Other key com- motors / G&N fail / 0.05g / Positive-X translation / mands to the SCC came from Launch 11 (9 for Apollos CM and SM separation / G&N entry mode / G&N PGNCS 4 and 6) change in velocity ΔV mode /G&N attitude control Control at KSC while the mission mode. G&N abort* / Positive- or negative-Z antenna was on the launch pad and from the switching* (* Removed for Apollos 4 and 6) Instrument Unit before separation of 25 S-IVB restart / LES jettison / Liftoff / the CSM from the S-IVB. IU 4 S-IVB-CSM separation Launch Arm/disarm pyrotechnics / Switch off logic buses / 12 Table 4 Key commands input to the Control Operate flight recorders / Restart MCP Mission Control Programmer.26 See Fuel cell purge / Lifting entry / SPS on-off / Pitch- Figure 11 for a diagram of the MCP and roll-yaw / Ullage / RCS propellant on-off / LES MCC 59 its interfaces. The MCP contained more jettison / Antennas on-off / CM-SM separation / than 1,050 relays.27 Radios on-off Q U E S T 25:3 2018 33 www.spacehistory101.com Figure 11. Mission control programmer interfaces.28

Third Device: Lunar Module the LM Mission Programmer The trajectory reconstruction esti- Mission Programmer (LMP). The LMP directed the sec- mated that the LM impacted in the ond and third firing of the descent Pacific Ocean 400 miles west of Apollo 5 was the first flight of engine, the separation of the Central America.30 the Lunar Module. It tested the descent and ascent stages, and the See Figure 12 for a compari- descent engine, separation of the first ascent engine firing. Then the son of planned and actual events ascent and descent stages during a MCC returned control to the during Apollo 5. Note that there simulated aborted landing, and the PGNCS. The next malfunction was a one-and-one-half hour peri- ascent engine. Despite several mal- occurred as the PGNCS operated od between the first ascent engine functions the mission objectives the RCS to maintain vehicle atti- firing and the second, during which were met. Under control of the tude but burned too much fuel PGNCS control of the LM led to PGNCS, the LM separated from because its calculations used the excessive RCS fuel expenditure. the S-IVB and began to execute the mass of the LM at the time of the planned program. The LM first malfunction before staging The Apollo 9 mission was a assumed a cold soak attitude for and the use of fuel during three manned flight test in Earth orbit of three hours, and then reoriented for engine firings. Control was the CSM and LM. The CSM had the first descent engine firing. The returned to the LMP for the second performed well on two previous first malfunction came at four sec- firing of the ascent engine. In the manned missions, Apollos 7 and 8, onds after the start of the first last malfunction, the LMP closed so the principal objective of Apollo descent engine burn, when the the fuel interconnect valves, lead- 9 was the first manned flight test of PGNCS shut down the engine pre- ing to fuel depletion for the RCS, the LM. The LM separated from maturely due to “incomplete sys- and the vehicle began to tumble the CSM and practiced descent, 29 tem coordination.” The MCC while the ascent engine was firing. ascent, and rendezvous maneuvers. shifted control from the PGNCS to

Q U E S T 25:3 2018 34 www.spacehistory101.com Figure 12. Control of Apollo 5 events.31

After docking with the PRA contained a program written on 35mm film read by a photodiode array. CSM and crew transfer to the It had a capacity of 64 kbits (about one-third the size of the rope memory of CSM, the unmanned LM was jetti- the LGC).35 PRA words were 8 bits long, and the program consisted of soned and the ascent engine was sequences. The film drive was bidirectional, so that the MCC could select fired to fuel depletion. The only which sequence to run. During Apollo 5, sequences III and V were executed unmanned portion of the mission while the LMP was in control of the vehicle. The DCA, a UHF transceiver was the last firing of the LM ascent and coder, received ground commands to control the LM. These commands propulsion system, which put it in a could be input to the LM Guidance Computer (part of the PGNCS), to the highly elliptical orbit (3,761 x 127 PRA, and to the PCA. The PCA connected the LMP to the reaction control miles).32 system; the descent engine; the ascent engine; and the explosive devices sub- Apollo 10 was a manned mis- system that separated the ascent and descent stages. The PCA contained a sion to the with the LM sep- arating from the CSM in lunar orbit, descending to nine miles above the surface of the Moon, and rejoining the CSM. After the LM crew reentered the CSM, the LM was jettisoned and the unmanned ascent stage fired to fuel depletion, putting it into a solar orbit.33 To control the LM during unmanned flight, the Lunar Module Mission Programmer (LMP) was developed by NASA and the LM contractor, Grumman Aerospace. The LMP could also replace some functions of the PGNCS if the latter malfunctioned. The LMP consisted of four compo- nents: a program reader assembly (PRA), a digital command assem- bly (DCA), a program coupler 36 assembly (PCA), and a power dis- Figure 13. Lunar Module mission programmer block diagram. tribution assembly (PDA).34 The Q U E S T 25:3 2018 35 www.spacehistory101.com decoder that received digital com- ent into the attitude it would hold engine for its last firing. Figure 14 mands from the LGC or from the for a three-hour cold-soak, and to shows that while the LGC could PRA and sent signals to the switch- maneuver to the attitude for firing issue ascent engine on/off com- ing subassembly. That contained a the descent engine. It initiated the mands, they would not be per- prime matrix of relays and another descent engine firing, but shut it formed without prior astronaut matrix that could be controlled down after just four seconds of the commands to pressurize and arm from the ground to replace relays in planned 38 second firing. The LM the engine. Pressurization involved the prime matrix that malfunc- Guidance Computer (LGC) entered opening six explosive valves, a tioned. Figure 13 is a block dia- idle mode (P00) after premature one-time operation. During Apollos gram of the LMP and its interfaces. shutdown, and the Mission Control 9 and 10, astronauts performed the Initially on the Apollo 5 mis- Center transferred control to the pressurization during ascent. For sion, after nose cone jettison and LMP and commanded the PRA to the final firing of the ascent engine SLA panel deployment, the read sequences III and V. Modified to fuel depletion, it was only neces- PGNCS controlled the LM to sepa- versions of the LMP flew on sary for the LMP to close the arm rate from the S-IVB stage, to reori- Apollos 9 and 10 to arm the ascent switch.

For Apollo 9 the LMP omitted PGNCS control to Abort Guidance the RCS was used to effect a con- the PRA and replaced the PCA with System control to execute the burn to trolled deorbit of the ascent stage. the ascent-engine arming assembly fuel depletion. Subsequent models of Controlled deorbit ended with impact (AEAA). The Apollo 10 version of the LM incorporated the AEAA into at a known location, which allowed the LMP replaced the UHF DCA the Control Electronics Section.38 calibrated measurement of data from with the Unified S-Band digital However, Apollo 10 was the last mis- seismometers left on the Moon. The uplink assembly and incorporated an sion to fire the ascent engine to LGC initiated the maneuver after the AEAA which could not only arm the depletion. Table 5 shows that during MCC signaled from the ground.39 ascent engine but could switch from Apollo missions 12, 14, 15, and 17 No deorbit was ordered during

Q U E S T 25:3 2018 36 www.spacehistory101.com Apollo 11, and LM-5 made an uncon- Summary trolled deorbit to an unknown crash site. AS-202, Apollo MISSION AS-201 Apollo 5 Apollo 9 Apollo 10 During Apollo 16, after ascent stage 4 & 6 SPACECRAFT CM without LM with LM with LM with jettison from the CSM, attitude control of CM with PGNCS the LM was lost and controlled deorbit CONFIGURATION PGNCS PGNCS PGNCS PGNCS CONTROL Automated Mission Control LM Mission LM Mission was not possible. [A] DEVICE control system Programmer Programmer Programmer The devices and their components Radio Ground Digital Digital Digital used to control unmanned Apollo space- GROUND COM- Command Command Command Command Uplink MUNICATIONS craft are shown in Table 6. The functions Control Controller Assembly Assembly Assembly of the components are shown in the first Program Sequential PROGRAM [B] Reader [B] [B] column. The sequential timer of AS-201 Timer was a mechanical clockwork device sim- Assembly Attitude Attitude and ilar to that used on the V-2. It was ATTITUDE Reference Deceleration [B] [B] [B] replaced on Apollo 5 by a film strip, REFERENCE System Sensor which was the backup to the program Ascent Ascent Automated Spacecraft Program stored on the LGC. The interface compo- INTERFACE TO Engine Engine Command Command Coupler nents in the last row were made of relays, SPACECRAFT Arming Arming Control Controller Assembly diodes, and time delays. Assembly Assembly Notes: [A] Function was performed by components of the Communications System and Control Acknowledgments Electronics System of the Lunar Module. [B] Functions were performed by the PGNCS. The author is grateful for the many suggestions Table 6. Evolution of control devices. made by his wife, Mariana T. Durbin, who copy- Notes edited this article. 1 Postlaunch Report for Mission AS-201, NASA MSC, 6 May 1966, Figure 4.0-1, p. 4-2; Postlaunch Report for Mission AS-202, About the Author NASA MSC, 12 October 1966, MSC-A-R-66-5, 4-2; Apollo 4 Edgar Durbin has worked part-time at the Mission Report, NASA MSC, January 1968, MSC-PA-R-68-1, 13-2. Smithsonian Institution National Air and Space 2 The SPS used Aerozine 50 (a 50/50 mix by weight of Museum, Department of Space History, since retir- hydrazine and unsymmetrical dimethylhydrazine) as fuel and ing from government service in 2002. Most of his nitrogen tetroxide (N2O4) as oxidizer. They immediately react on research there has been on the navigation, control, contact (hypergolic). and guidance of rockets. He received a bachelor of 3 S.I. Jimenez and B.C. Grover, Apollo Training: Apollo Spacecraft arts degree in mathematics from Harvard University & Systems Familiarization. Course Number APC-118, North in 1962, a bachelor of arts degree in physics from American Aviation, Space Division, Downey, CA. 15 August 1967. Oxford University in 1964, a doctorate in physics 4 Apollo Operations Handbook, Command and Service Module, from Rice University in 1972, and master’s degree in Spacecraft 012, SM2A-03-SC012, 12 November 1966, Figure 1-3. public administration from the Kennedy School of 5 Apollo Program Fight Summary Report, Apollo Missions AS- Government at Harvard in 1977. 201 through Apollo 16, NASA Office of Manned Space Flight, June 1972. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/ MISSION SPACECRAFT UNMANNED MANEUVER 19740013403.pdf Apollo 9 CSM 104, LM-3 Ascent engine fired to depletion 6 Postlaunch Report for Mission AS-201, Table 5.0-I. Apollo 10 CSM 106, LM-4 Ascent engine fired to depletion 7 Results of the First Saturn IB Launch Vehicle Test Flight AS- Apollo 11 CSM 107, LM-5 None 201, NASA MSFC, 6 May 1966. Table 4-I. Apollo 12 CSM 108, LM-6 RCS fired to controlled deorbit 8 For vehicle mass, see AS-201 Results Table 6-II. For thrust, Apollo 13 CSM 109, LM-7 Mission aborted see AS-201 Results Figure 9-6 and Figure 8-2. Apollo 14 CSM 110, LM-8 RCS fired to controlled deorbit 9 AS-201 Results, Figure 12-14. Apollo 15 CSM 112, LM-10 RCS fired to controlled deorbit 10 Gene F. Holloway, Automated Control System for Unmanned Apollo 16 CSM 113, LM-11 None Mission AS-201, NASA JSC, July 1975, NASA TN D-7991, Table II. SPS burn 1 started 1211.2 sec. AS-201 Results, Table 4-1, Apollo 17 CSM-114, LM-12 RCS fired to controlled deorbit Achieved Separation Attitude 728.31. 1211.2-728.31=482.89 Table 5. Maneuvers of unmanned Lunar Modules40 sec= 8.05 min. 11 Postlaunch Report for Mission AS-201, Table 5.0-I, 5-7. 12 Postlaunch Report for Mission AS-201, Figure 2.0.1

Q U E S T 25:3 2018 37 www.spacehistory101.com 13 AS-201 Results, Table 21-1, 261; Table 22 Apollo 4 Mission Report, NASA MSC, 31 Apollo 5 Mission Report, Figure 2-1, 2-6. 4-1, 8; Postlaunch Report for Mission AS- January 1968, MSC-PA-R-68-1, Section 1.0. 32 Apollo 9 Mission Report, NASA MSC, 201, Figure 20-1, 2-3. 23 The spelling “programer” (one m) was May 1969, MSC-PA-R-69-2, 7-9. 14 Michael Interbartolo, Apollo Guidance, used consistently in the 1975 Apollo 33 Apollo 10 Mission Report, NASA MSC, Navigation, and Control (GNC) Hardware Experience Reports about the MCP and the August 1969, MSC-00126, 3-2. Overview, NASA JSC, 2009. Briefing slides, LMP. The spelling used in the 1966 MSC PDF 60 pages. postlaunch report on mission AS-202 was 34 Jesse A. Vernon, Lunar Module Mission “programmer.” Programmer, NASA JSC April 1975. NASA TN 15 Holloway AS-201, 2, Figure 1. D-7949. 24 Gene F. Holloway, Mission Control 16 Holloway AS-201, 2. Programer for Unmanned Missions AS-202, 35 Eldon C. Hall, General Design Charact- 17 Holloway AS-201, Table II, 4. Apollo 4, and Apollo 6, NASA JSC, July 1975, eristics of the , MIT Instrumentation Laboratory, May 1963, 4. 18 Adapted from Figure 2.3-1, Apollo TN D-7992, 3. Operations Handbook Command and 25 Holloway, Mission Control Programmer. 36 Diagram based on text description in Service Module Spacecraft 012, 2.3-2, Vernon, LMP. 26 Holloway, Mission Control Programmer. North American Aviation, 12 November 37 Lunar Module News Reference, 1966, SM2A-03-SC012. 27 Holloway, Mission Control Programmer, 43. Grumman Aerospace Public Affairs, MP-16. 19 Apollo Operations Handbook Command 28 Holloway, Mission Control Programmer, https://www.hq.nasa.gov/alsj/LM_%20New and Service Module Spacecraft 012, Figure Figure 4 with changes. sReference_%28267_pp%29.pdf 2.3-8, 2.3-58. 29 The MSC made a change in the mission 38 Apollo Operations Handbook Lunar 20 Adapted from Figure 2.3-8, Apollo plan that was not communicated to the LGC Module LM 10 and Subsequent, Vol 1, Operations Handbook Command and designers at MIT. Don Eyles, Sunburst and Subsystems Data, Grumman, LMA790-3-LM Service Module Spacecraft 012, 2.3-58 and Luminary, An Apollo Memoir, 4; Final Flight 10 and Subsequent, 2.1-24. https://www. from Interbartolo, Apollo GNC Overview. Evaluation Report Apollo 5 Mission, NASA hq.nasa.gov/alsj/LM10HandbookVol1.pdf Office of Manned Space Flight, October 21 Ernest R. Hillje, Entry Flight 39 Apollo 12 Spacecraft Commentary, 1968, D2-117017-2 Rev. C, 29. Aerodynamics from Apollo Mission AS-202, NASA MSC, 473/1. https://www.jsc.nasa. NASA MSC, October 1967, NASA TN D-4185, 30 Apollo 5 Mission Report, NASA JSC, gov/history/mission_trans/AS12_PAO.pdf Figure 5. March 1968, MSC-PA-R-68-7, 1-2. 40 Various mission reports.

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