Apollo, The Early Missions
Created | Updated Sep 10, 2013
Project Apollo: The Beginnings
| Mission Planning
| Landing Site Selection
| Earthbound Support Systems
Astronaut Selection and Training
| The Saturn V
| The Saturn 1B
| The Apollo Spacecraft
Guidance and Navigation
| Command and Service Modules
| The Lunar Module
Assembling and Launching
| Pathfinders
| The Early Missions
| Apollo 11, The First Landing
The Intermediate Missions
| Apollo 15 Exploration
| Apollo 16 Exploration
| Apollo 17 Exploration
Skylab and Apollo-Soyuz
| Conclusion
Following a series of ten test launches of the Saturn 1 first stage between October 1961 and July 1965, the Apollo missions began with a series of unmanned test flights designed to prove the integrity of the craft and its systems. The initial three flights were not originally given Apollo flight numbers. Instead, they were referred to by their construction assembly number using the designation AS for Apollo-Saturn. The series number from 200 designated the use of the Saturn 1B booster.
The Saturn 1B first stage booster built by Chrysler, and using eight upgraded Rocketdyne J-2 engines, was to be used throughout the Apollo program for both manned and unmanned earth orbit flights, including the Skylab and Apollo-Soyuz flights.
The Flight of AS-201
After a delay of three days due to bad weather, and further 'holds' during the countdown for faults to be corrected as they arose, the first unmanned flight (AS-201) was launched on 26 February, 1966, from Cape Canaveral's eastern test range launch pad 34 to carry out development of the launch vehicle and the command and service modules.
Using a Saturn 1B first stage booster mated directly to a S-IVB third stage, AS-201 completed a sub orbital flight lasting 37 minutes, reaching an altitude of 303 miles. It demonstrated the correct separation of the stages, the separation of the LET from the command module, and the separation of command and service modules. Also on re-entry it verified the integrity of the CM's new heat shield from low orbit.
AS-201 also presented a number of problems, of which the failure of the service module's engine to burn correctly after only 80 seconds of its planned test firing and a rolling re-entry of the command module due to loss of its steering control were among the most serious. The engine problem proved to be due to a leaking helium pipe, which allowed the inert gas, used to pressurize the fuel tanks, to be mixed with the oxidizer and ingested into the engine, causing a loss of pressure and temperature. Nevertheless, the flight was considered successful, and the command module was recovered from the Atlantic Ocean after splashdown by the USS Boxer.
The Flight of AS-203
To allow time for the SM's engine problem to be sorted out, and to minimize delays in the test program, it was decided to fly AS-203 out of order, as it was not scheduled to carry a spacecraft payload. AS-203 was to study the fluid dynamics of the liquid hydrogen fuel inside the S-1VB's tanks under weightless conditions. Also under evaluation was the instrument and guidance systems of the launch vehicle under orbital conditions. Countdown on launch pad 37B was initially delayed due to the failure of one of the two television cameras viewing the interior of the tank. Countdown resumed with the decision to go with only one camera operating, and the Saturn 1B booster duly lofted the S-IVB third stage into an orbit 116 miles high on 5 July, 1966. After separation from the booster it completed four earth orbits, while engineers examined the behaviour of the fluid in the tank. The S-1Vb stage was allowed to re-enter and burn up in the atmosphere.
The Flight of AS-202
The third test, designated AS-202 on 25 August, 1966, was another sub orbital flight carrying unmanned command and service modules. The countdown was interrupted several times by problems requiring rectification before committing to the launch. A hold of 60 minutes, due to the loss of the digital computer during a power transfer test, as the spacecraft went onto internal power, another hold of 48 minutes for the same problem, and finally one of 41 minutes, due to loss of a remote data processor, kept AS-202 on the ground; but eventually the flight lifted off from pad 34 and reached an altitude of 715 miles, lasting 33 minutes.
The flight successfully re-ran the tests of the Saturn's first and second stage separation, and the jettisoning of the boost protection cover from the command and service module. During the flight the CSM was separated from the launch vehicle and the crucial re-test of the SM's engine carried out. The engine was started up four times and run for a total of over three minutes, during which time it performed faultlessly. The final tests of command and service module separation and re-entry to test the CM's heat shield went without fault, but a steeper than planned re-entry path caused the capsule to miss the splashdown rendezvous with the USS Hornet in the Atlantic by some 230 miles.
Apollo 1
If we die we want people to accept it. We are in a risky business and if anything happens to us we hope it will not delay the program. The conquest of space is worth the risk of life.
- Astronaut Virgil Grissom, after Gemini (3 March, 1965).
On 27 January, 1967, what was scheduled to be the first manned Apollo flight (designated at that time AS-204) was undergoing tests and routine training with astronauts Virgil 'Gus' Grissom, Edward 'Ed' White, and Roger B Chaffe on board the command module. Disaster struck suddenly as fire broke out inside the CM. The first indication was a report, believed to be Chaffee, heard over the capsules communication link at 6:31:04 PM EST: 'There's a fire on board...'
The pad leader ordered immediate evacuation of the capsule, but 15 seconds later the CM ruptured and filled the surrounding 'White Room' access area at the end of gantry access arm 8 with dense, acrid smoke and flame, igniting combustible material in the room and forcing the personnel to retreat to the access arm. Rescue attempts by the White Room personnel began within seconds, but were hampered by lack of breathing equipment and the smoke, which had now reduced visibility to a few inches. To gain access to the capsule, it was necessary to remove three hatches, the outer Boost Protection Cover hatch, an intermediate Ablative Hatch (which would have become the outer hatch after jettisoning the BPC in flight), and the inner CM hatch. The first two hatches opened outwards, but the CM hatch opened inwards into the capsule! Using the only available smoke masks, and working in relays (while having to repeatedly retreat to the gantry access arm to breathe), the ground crew managed to open all three hatches within five minutes, but voice transmission from inside the capsule had ceased three seconds after the capsule ruptured. All three astronauts perished in the inferno, which had resulted from an electrical short circuit, igniting wiring and flammable material, and fuelled by the pure oxygen atmosphere inside the capsule at above atmospheric pressure.
Gus Grissom had been the second American in space with a sub orbital flight in a Mercury capsule named Liberty Bell on 21 July, 1961. He flew again in Molly Brown, the first manned Gemini mission. Ed White had been the first American 'space walker' in Gemini 4 on 3 June, 1965. Roger Chaffee was the 'rookie' of the crew, and, at 31 years of age, had been the youngest astronaut chosen to fly at that time. The mission was subsequently confirmed to be designated Apollo 1 in honour of the three astronauts to die in the American space program.
The launch pad fire of Apollo 1 set the space program back almost a year while an inquiry into the cause and safety procedures was undertaken. The spacecraft was completely stripped for examination but the actual cause of the fire was never positively established. It was thought that faulty wiring near the environmental system adjacent to one of the crew's couches was the source of the fire. The resultant findings required a redesign of the capsule with less flammable material and a modified environmental support system with an internal atmosphere of oxygen and nitrogen during the launch. The hatch system, which had required a minimum of 90 seconds for the crew to open by undoing a series of clamps, was also redesigned for easier outward opening within 5 seconds.
The fire forced a rethink that ultimately may have saved the Apollo program. If the fire had occurred in space during a manned mission it would almost certainly have resulted in the loss of a crew in unknown circumstances and the ramifications may well have resulted in the cancellation of the program.
Apollo 4
On 9 November, 1967, testing resumed with the launch of Apollo 4. It was an important milestone in the Apollo program, being the first launch of the complete Saturn V moonship, using the S-IC first stage and S-11 second stage boosters. It was to carry a payload of another unmanned CSM and a 'boilerplate' non flying mock up of a lunar module into earth orbit for testing. This was the first time that the full Saturn 1C first stage, S-11 second stage, and S-1VB third stage configuration had been used together.
The giant S-1C first stage, developing seven and a half million pounds of thrust, shook the ground and the spectators three miles away at launch control as it lifted off launch pad 39A to carry its payload towards earth orbit. After two orbits the S-1VB third stage was restarted under remote control to boost the CSM to a height of 10,000 miles. After separation from the S-1VB, the Service Module's engine was fired to increase the spacecraft's altitude to over 11,000 miles and orientated to place the CM's heatshield in shadow. After a four hour period of evaluation and allowing the heatshield to cold-soak the CSM , was dived back towards Earth under power of the SM's engine, at a point over the Pacific Ocean near Hawaii. The CM was separated from the SM as it attained a speed of over 25,000 mph to simulate the high-speed re-entry of the earth's atmosphere that would occur on the return flights from the moon. This successfully checked out the function of the CM's heat shield at the high speed of re-entry and the capsule was picked from the water by the USS Bennington.
Apollo 5
The unmanned Apollo 5 lifted off on 22 January, 1968, from launch pad 37 for its eight-hour, five-orbit mission using the S-IB booster that had been originally scheduled to launch the ill fated Apollo 1 flight. It was carrying the first flying lunar module, LM-1, on top of the S-1VB stage, but minus its landing legs, as no landing was to be attempted. Once in earth orbit and under remote command from mission control, the LM was separated from the S-IVB and pulled clear using its attitude thrusters. The planned manoeuvres were to check the LM's guidance and abort systems in flight; and, after two earth orbits, the LM's descent engine was to be fired up and its restarting and throttling capabilities tested during a twelve minute burn. Further tests were to follow separating the descent and ascent stages and testing the restart capability of the ascent engine.
Once in earth orbit the LM was separated from the S-IVB and for two orbits made ready for the initial test of the descent engine and its crucial throttling capability. Under command from mission control, the engine was fired up, but four seconds later it was shut down by the on-board computer, which sensed that engine thrust had not built up quickly enough. The fault however, was in the computers programming which did not allow sufficient time for the event.
Flight controllers postponed further tests for another orbit until they worked out a way around the computer fault and adopted an alternative flight plan which combined the descent engine throttle test with a 'Fire in the Hole' (FITH) abort test. This involved throttling up the descent engine to maximum thrust at the end of its test and starting the ascent engine while firing the pyrotechnics that separated the stages to simulate an emergency mission abort. Both manoeuvers went as planned.
The final test of the ascent engine to confirm that it would restart after the FITH test and continue to run until its fuel was exhausted now required an updating of the on-board computer data for the revised mission. Due to the delay caused by the original computer fault and the earth's rotation the LM's orbit was now drifting out of range of the earth tracking stations and controllers were experiencing difficulty communicating with the spacecraft. They had only one remaining orbit in which they could complete the test and due to the re-configured mission the LM's attitude control thrusters were running low on fuel. The update was transmitted through the Australian Carnarvon tracking station to be followed by the fire command from the Hawaii station. There was just sufficient time to complete the test and the LM ended its short life in a fiery re-entry over the west coast of Panama.
Apollo 6
The take off of Apollo 6, intended as a test development flight of the Saturn V, was the last unmanned flight and was marred with incidents. Two minutes after lift off, on 4 April, fluctuations in the thrust of the Saturn's engines brought on low frequency modulations through the complete frame of the Saturn V. Known as the 'pogo' effect, it had been apparent in all of the Saturn launches; but, in this case, the bouncing vibration had exceeded the design limitations by over a 100 per cent, causing a panel in the adapter ring between the first and second stages to come adrift in flight. After jettisoning the first stage and the ignition of the second stage, two of the second stage's five J-2 engines cut out. Although the remaining three ran for longer to compensate, the rockets speed was less than that required to reach its intended height before it ran out of fuel. The third stage also had to run longer to reach the required speed for orbit; but, even so, it only acquired an uneven elliptical orbit, instead of the circular one intended.
After considering the position for two orbits, Mission Control tried to restart the S-IVB's engine to simulate a Trans Lunar Injection (TLI), but the motor could not be persuaded to fire up for a second time. The flight engineers were now forced to abandon the lifeless third stage and switch to an alternative back up mission. Separating the CSM from the dead S-IVB, they fired the SM's engine for over 7 minutes to simulate the TLI burn. This propelled Apollo 6 to a height of 13,000 miles, from which they planned another simulated high-speed re-entry. Diving back towards the atmosphere, the SM's engine was unable to push the CM to a high enough velocity due to lack of fuel; and, although re-entry was successful, the spacecraft fell short of its predicted splashdown point by 50 miles. The CM was recovered from the Pacific by the USS Okinawa.
Apollo 7
Apollo 7, the first manned Apollo flight, was launched on 11 October, 1968, using a S-IB booster to obtain earth orbit. Crewed by Walter Schirra, Don Eisele, and Walter Cunningham, it flew 163 earth orbits. During the flight the CSM separated from the Saturn's S-IVB stage, turned 180 degrees, and prepared to dock with a target in the top of the Saturn to simulate the transposition and docking manoeuvre that would be necessary to extract a LM from its housing. Unfortunately, the panels that covered the target in the LM's storage bay had not fully opened, and this prevented the crew from carrying out the docking manoeuvre. The panels were modified on subsequent missions to be released by firing explosive bolts, which insured their correct deployment.
Mission commander Schirra, who had initially been against TV coverage as an unnecessary distraction on the mission, cut one of the planned TV broadcasts, but later relented, and the first live television pictures were beamed back to earth from space. The crew demonstrated the weightless conditions in the capsule on live coverage, showing globules of water and various articles floating freely in the weightless conditions. On a later broadcast, they showed impromptu cards with messages like Keep those cards and letters coming in folks and Hello from the lovely Apollo room, high atop everything.
Further tests on the Service Module's engine included the first manned firing of the SM's engine in flight. The test firings went without malfunctions and produced a one hundred per cent correct operational record. Without the weight of a lunar module the first firing of the engine caused Schirra to exclaim 'Yabba dabba dooo!!1' as the acceleration plastered them into their seats and gave them 'a real boot in the rear'.
During the flight, all three astronauts developed head colds. A cold on Earth is a minor discomfort; but, under weightless conditions, mucus cannot drain 'downwards'; so it continues to fill the nasal passages, which have to be constantly cleared by hard blowing to prevent blockage of the ears and nose. Although the crew took decongestants, they were concerned that they would be unable to clear their stuffed heads with their helmets on during re-entry. Mission control was more concerned that the change in pressure inside the module during the descent would cause burst eardrums as the capsule automatically adjusted the internal pressure, and tried to persuade the crew to keep their helmets on. But Schirra was adamant and vetoed that. The crew took more decongestants and re-entered without their helmets, luckily without mishap. After 260 hours in orbit, they splashed down in the Atlantic south east of Bermuda, to be picked up by the USS Essex.
Apollo 8
The flight of Apollo 8 to orbit the moon did not originally figure in NASA's planned program; but development of the Lunar Module was proving difficult. In order to insure against further delay - and no doubt with an eye on public relations - it was decided to include a manned mission to orbit the moon without attempting a landing. This would also allow the Earth tracking systems to be checked out on a lunar flight, while at least partly fulfilling President Kennedy's challenge by taking a man to the moon and returning him safely.
Apollo 8 was launched just before Christmas 1968, on 21 December, with Frank Borman, James Lovell, and William Anders on top of the Saturn 5 in the CSM. It did not carry a LM, as no landing was to be attempted. After one Earth orbit capcom Michael Collins gave the historic authority to the crew You're Go for TLI and the third stage S-1VB engine was restarted for a Trans Lunar Injection (TLI) burn, which accelerated the CSM to 24,200 mph placing it on a 'free return' course that would take it around the moon and back to Earth if left uncorrected.
On Christmas Eve, 1968, Apollo 8 reached its objective and swung around the far side of the moon. For the first time an Apollo crew experienced complete isolation from Earth when they lost contact with Mission Control, as the radio signal was blanketed out by the moon. The Loss of Signal (LOS) occurred each time Apollo disappeared behind the moon and Mission Control would have to wait to 'Acquire the Signal' (AOS) as they reappeared on the other side. Out of sight and without communication with the Earth the astronauts started the Service Modules engine retrograde to its line of flight, slowing the craft into an elliptical orbit; and, after a second firing, brought the craft into a 69-mile high lunar orbit. Apollo 8 spent 20 hours completing ten orbits, during which they photographed prospective landing sites and transmitted TV pictures of a rolling lunar landscape, showing a desolate, greyish white landscape pock marked with craters and mountains picked out starkly in bright sunlight and dark shadow. Also for the first time, 'Earthrise' was seen rising from beyond another celestial body's horizon. Lovell remarked, 'The vast loneliness is awe inspiring, and it makes you realize just what you have back there on earth.'
During the penultimate orbit, the crew read a passage from Genesis, the first book of the Bible.
William Anders:
For all the people on Earth the crew of Apollo 8 has a message we would like to send you... 'In the beginning God created the heaven and the Earth. And the Earth was without form, and void, and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters. And God saw the light , that it was good: and God divided the light from the darkness.'
Jim Lovell:
'...And God called the light day, and the darkness he called night. And the evening and the morning were the first day. And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters. And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament, and it was so. And God called the firmament heaven. And the evening and the morning were the second day.'
Frank Borman:
'... And God said, Let the waters under the heavens be gathered together unto one place, and let the dry land appear, and it was so. And God called the dry land Earth, and the gathering together of the waters called he seas. And God saw that it was good.'
Borman then added,
And from the crew of Apollo 8, we close with a good night, good luck, a Merry Christmas, and God bless all of you, all of you on the good Earth.
During the flight, as they transmitted TV pictures back to earth of the rolling moonscape, the crew and mission control became absorbed in conversation and naming craters after prominent NASA figures. Flight controller John Aaron was the only one to notice that the crew were in danger of missing one of their 'housekeeping' duties, and that the environmental system required adjustment. He was promptly rewarded by having a crater - 'Aaron' - named after him.
Later that day, the SM's engine was started again for the Trans Earth Injection (TEI) homeward flight, pushing Apollo 8 out of lunar orbit and into a return path on a closely defined trajectory that would bring it back to Earth. The approach to re-entry of the Earth's atmosphere has to be inside a narrow corridor to be successful. The attraction of the Earth's gravity would accelerate the craft to a speed of 25,000 mph; and if the angle of approach was too shallow the Command Module would skip off the atmosphere and head out into an orbit around the sun, while approaching too steeply would mean burning up in the atmosphere on re-entry.
Apollo 8 successfully re-entered on 27 December, 1968; but, upon splash down in the Pacific, the module inverted, leaving the three astronauts hanging in their straps. Borman had to inflate flotation bags in the CM's nose to right the craft. The crew then had to wait until daylight to be recovered by the USS Yorktown. The first manned mission to another planetary body, which Borman described as 'a most fantastic voyage' was completed.
Apollo 9
The Command and Service module's systems had now been proved adequate, and only the lunar module and the lunar EVA suit remained to be fully tested in flight. Development of the LM had proved troublesome, requiring significant redesign and structural modifications after the catastrophic fire onboard Apollo 1. On 3 March, 1969, Apollo 9 was launched into earth orbit for a full shakedown test of the complete Apollo lunar hardware in flight. The launch had been delayed three days due to all three crewmembers (James McDivitt, David R Scott, and Russel L Schweikart) picking up head colds. Once in orbit, Scott separated the CSM, now given the name 'Gumdrop' by the crew; docked with the LM, named 'Spider'; and withdrew it from the top of the third stage, after which the S-4B's engine was fired again to place it into a solar orbit.
For four days, a complete test of all the Command Module systems followed, including three separate firings of the service module's engine, a critical manoeuvre, as it was the first time it had been used to propel the combined mass of the linked 'Apollo' CSM and LM combination. The third firing pushed the combined Spider/Gumdrop into a higher orbit ready for tests of the lunar module.
The following day, while donning the pressure suits prior to entering the LM, McDivitt and Schweikart both became disorientated. Schweikart suddenly vomited, but was able to contain it long enough to find a bag. They transferred into the lunar module and powered it up ready to check the craft out. After extending the landing gear, Schweikart's discomfort continued and he vomited again; but he recovered sufficiently, after a rest period, to continue with the LM's tests. Schweikhart and McDivitt took control of Spider/Gumdrop and fired the lander's descent engine to slow the craft into a lower orbit. The engine test was satisfactory, and the LM was closed up for the day.
Also under evaluation was a new space suit and the Personal Life Support System (PLSS) backpack, which was to be used on the lunar surface. On their second excursion into the LM, Schweikart was due to space walk from the lunar module to the command module to simulate a rescue transfer between the craft in the event of them not being able to dock together. This space walk was cancelled, however, due to the risk that either of the crew might become ill again inside their suits during the transfer.
Schweikart's discomfort was attributed to a reaction to decongestants that had been used to dry up his cold, and he eventually recovered sufficiently to allow a modified space walk to take place. After depressurising the command and lunar modules, Schweikart stood up in the lunar modules hatchway, while Scott exited the command module's hatch, so that they could take photographs of each other standing in their respective doorways. At this point Schweikart was effectively flying in a self-contained spacecraft with a tether line his only connection to the lunar module. During this EVA he was referred to by his own callsign 'Red Rover'.
On 7 March, with McDivitt and Schweikart aboard Spider, Scott (in Gumdrop) released the Lunar Module into free flight. The lander hung up on the docking latches on the first try, but a second attempt was successful. After testing the attitude thrusters, the lander drifted clear of the CSM and fired its main descent engine at ten per cent thrust to separate the two craft to 15 miles. As the power was increased the engine began to vibrate, but cleared when it was shut down and restarted. Spider moved away to a distance of over 100 miles above and behind the CSM. To bring the craft together again Spider fired its thrusters against its line of flight to slow the craft into a lower orbit below Gumdrop, allowing it to catch up. The final test to separate the ascent stage from the descent stage produced a shower of debris around the craft, as the explosive charges blew off the foil covering the lander's bottom half and damaging its blinking navigation light. McDivitt fired the ascent engine to narrow the gap between the two craft; and, after two hours catch-up, Gumdrop latched on to Spider. As the LM approached for docking Scott in the command module said 'Boy, you've got contraptions hanging out all over'. McDivitt replied 'Well, that's show business'.
The manned LM had now flown up to 6 hours, separated from its parent craft, and was deemed to be ready for lunar flight. Spider was released for the last tine, and allowed to re-enter and burn up in the earth's atmosphere. 'Gumdrop continued circling the earth until after 10 days in orbit, the crew released the service module to follow Gumdrop, and re-entered on 13 March. Gumdrop and its crew were picked out of the Pacific by the USS Guadal Canal.
Apollo 10
The Apollo 10 mission with its crew of Eugene A Cernan, John W Young, and Thomas P Stafford was the last test flight and a full dress rehearsal for the Apollo 11 landing attempt, duplicating every aspect of the flight down to within 50,000 feet of the lunar surface. Launched on 18 May, 1969, it was the only Apollo mission to start its flight from launch pad 39B, and the launch was marred by heavy pogo vibration through the craft, as it powered its way through the atmosphere, although it obtained its parking orbit satisfactorily. The docking and transposition manoeuvre of the CSM and the LM (named Charley Brown; and Snoopy respectively) was carried out on the way to the moon after the Trans Lunar Injection (TLI) burn, and Apollo 10 braked into lunar orbit on 21 May. For the first six hours in orbit, the second crew to visit the moon relayed colour television pictures and their description of the surface back to earth. They also took photographs of the prime landing sites on the Sea of Tranquillity, scheduled for the next mission in two months later.
The following day Stafford and Cernan, aboard Snoopy, prepared for separation from Charley Brown, leaving Young on board. A hitch developed as they prepared to undock, and they were at first unable to fully depressurise the access tube connecting the two craft. They also found that there was a 3-degree twisting out of alignment of the CSM and LM, which may have occurred during the previous docking. The concern was that the holding latches may have been damaged and the two craft would be unable to re-dock after separation. If this occurred, Stafford and Cernan would be unable to re-enter the command module and would be stuck in lunar orbit, unless they could regain access by space walking between the two craft. As they disappeared behind the moon, mission control advised the crew that the misalignment was safe up to six degrees, but not to attempt undocking if the problem became more serious. The two craft emerged on the other side undocked and flying in line.
Using its thrusters, Snoopy descended below Charley Brown, and its descent engine was started up for a 30 second burn to begin Descent Orbit Insertion (DOI). The craft descended to within 47,000 ft of the lunar surface, simulating a descent approach to a landing, and taking photographs as they descended. At the low point of the orbit, 300 miles east of the planned Apollo 11 landing site, they fired the descent engine again to increase the height of the orbit on the far side of the moon. The new elliptical orbit brought them swooping around again low over the proposed Apollo 11 site.
As no landing was to be attempted on this flight, Stafford and Cernan prepared to jettison the descent stage (to simulate an abort of the landing approach) and return to rendezvous with Charley Brown. Suddenly, Snoopy went into a wild lurching change of attitude. An angry Cernan's exclamation 'son of a bitch...! was transmitted live to world audiences as he fought to bring Snoopy to heel. A master warning light came on showing the internal measurement unit, part of the on board computer, was reaching its limits as it neared gimbal lock2 Stafford jettisoned the descent stage, took manual control and with a manoeuvre using the thrusters, corrected the flight path alignment. The problem was caused by a switch for the Abort Guidance System left in an incorrect 'automatic' mode. Snoopy had taken charge of the flight, and automatically started manoeuvring to rendezvous with the Command Module, as it was programmed to do in that mode.
Rendezvous and docking of the two craft was completed successfully after testing out the rendezvous Radar at a maximum range of 350 miles. After transferring successfully to Charley Brown, the wayward Snoopy's engine was fired up, and the module sent into orbit around the sun. The SM's engine started for the homeward leg, and Charley Brown splashed down on 26 May.
Meanwhile, the Apollo 11 moonship had begun its slow journey to launch pad 39A at Kennedy Space Center...