APOLLO 12

The Sixth Mission:

The Second Lunar Landing

14 November–24 November 1969

 

 

Background

 

Apollo 12 was a Type H mission, a precision piloted lunar landing demonstration and systematic lunar exploration. It was the second successful human landing on the Moon.

 

The primary objectives were:

 

 

 

 

 

 

The all-Navy crew included Commander Charles “Pete” Conrad, Jr. (USN), commander; Commander Richard Francis “Dick” Gordon, Jr. (USN), command module pilot; and Commander Alan LaVern Bean (USN), lunar module pilot.

 

Selected as an astronaut in 1962, Conrad was making his third spaceflight. He had been pilot of Gemini 5 and command pilot of Gemini 11. Born 2 June 1930 in Philadelphia, Pennsylvania, Conrad was 39 years old at the time of the Apollo 12 mission. He received a B.S. in aeronautical engineering from Princeton University in 1953.[1] His backup was Colonel David Randolph Scott (USAF).

 

Gordon had been pilot of Gemini 11. Born 5 October 1929 in Seattle, Washington, he was 40 years old at the time of the Apollo 12 mission. Gordon received a B.S. in chemistry from the University of Washington in 1951, and was selected as an astronaut in 1963. His backup was Major Alfred Merrill Worden (USAF).

 

Bean was making his first spaceflight. Born 15 March 1932 in Wheeler, Texas, he was 37 years old at the time of the Apollo 12 mission. Bean received a B.S. in aeronautical engineering from the University of Texas in 1955, and was selected as an astronaut in 1963. His backup was Lt. Colonel James Benson Irwin (USAF).

 

The capsule communicators (CAPCOMs) for the mission were Lt. Colonel Gerald Paul Carr (USMC), Edward George Gibson, Ph.D., Commander Paul Joseph Weitz (USN), Don Leslie Lind, Ph. D., Scott, Worden, and Irwin. For this mission, there were also four civilian backup CAPCOMs: Dickie K. Warren, James O. Rippey, James L. Lewis, and Michael R. Wash. The support crew members were Carr, Weitz, and Gibson. The flight directors were Gerald D. Griffin (first shift), M. P. “Pete” Frank (second shift), Clifford E. Charlesworth (third shift), and Milton L. Windler (fourth shift).

 

The Apollo 12 launch vehicle was a Saturn V, designated SA-507. The mission also carried the designation Eastern Test Range #2793. The CSM was designated CSM-108, and had the call-sign “Yankee Clipper.” The lunar module was designated LM-6, and had the call-sign “Intrepid.”

 

 

Launch Preparations

 

The terminal countdown started at T-28 hours at 02:00:00 GMT on 13 November. Scheduled holds were planned at T-9 hours for 9 hours 22 minutes and at T-3 hours 30 minutes for one hour. However, spacecraft preparations on November 12, a leak developed in the CSM LH2 tank No. 2 during cryogenic loading. The tank was drained and replaced using a tank from the Apollo 13 CSM. An unscheduled hold was initiated on 13 November at T-17 hours (12:00:00 GMT) for retanking cryogenics in the CSM. Loading was completed in six hours and the count resumed at 19:00:00 GMT. The scheduled hold at T-9 hours was reduced by six hours, thereby averting a launch delay.

 

A cold front was moving slowly southward through the central section of Florida. This front produced the rain showers and overcast conditions that existed over the pad at launch time. Stratocumulus clouds covered 100 percent of the sky (base 2,100 feet), the temperature was 68.0° F, the relative humidity was 92 percent, and the barometric pressure was 14.621 lb/in2. Winds, as measured by the anemometer on the light pole 60.0 feet above ground at the launch site, measured 13.2 knots at 280° from true north.

 

 

Ascent Phase

 

Apollo 12 was launched from Kennedy Space Center Launch Complex 39, Pad A, at a Range Zero time of 16:22:00 GMT (11:22:00 a.m. EST) on 14 November 1969. The planned launch window extended to 19:26:00 GMT to take advantage of a sun elevation angle on the lunar surface of 5.1°.

 

Apollo 12 was the first Saturn vehicle launched during a rainstorm, following the decision to waive Manned Space Flight Center Launch Mission Rule 1-404, which stated:

 

“The vehicle will not be launched when its flight path will carry it

 through a cumulonimbus (thunderstorm) cloud formation.”

 

The reason for the rule was that the Saturn V was not designed to withstand thunderstorm conditions during launch.

 

Between 000:00:12.8 and 000:00:32.3, the vehicle rolled from a launch pad azimuth of 90° to a flight azimuth of 72.029°.

 

At 000:00:36.5 there were numerous space vehicle indications of a massive electrical disturbance, followed by a second disturbance at 000:00:52. The crew reported that, in their opinion, the vehicle had been struck by lightning, and that the fuel cells in the service module were disconnected and that all A/C power in the spacecraft was lost. Numerous indicator lamps were illuminated at this time.

 

Ground camera data, telemetered data, and launch computers later showed that the vehicle had indeed been struck by lightning. Virtually no discernible effects were noted on the launch vehicle during the second disturbance.

 

Atmospheric electrical factors and the fact that the vehicle did not have the capacitance to store sufficient energy to produce the effects noted indicated that the first discharge was triggered by the vehicle. The second disturbance may have been due to a lesser lightning discharge. The launch vehicle hardware and software suffered no significant effects, and the mission proceeded as scheduled. Because the lightning was self-induced, and because the vehicle did not fly through cumulonimbus clouds, it was determined that Rule 1-404 had not been violated.

 

The S-IC engine shut down at 000:02:41.74, followed by S-IC/S-II separation, and S-II engine ignition. The S-II engine shut down at 000:09:12.34 followed by separation from the S-IVB, which ignited at 000:09:16.60. The first S-IVB engine cutoff occurred at 000:11:33.91, with deviations from the planned trajectory of only -1.9 ft/sec in velocity and only 0.2 n mi in altitude.

  

The S-IC stage impacted the Atlantic Ocean at 000:09:14.5 at latitude 30.273° north and longitude 73.895° west, 365.2 n mi from the launch site. The S-II stage impacted the Atlantic Ocean at 000:20:21.6 at latitude 31.465° north and longitude 34.214° west, 2,404.4 n mi from the launch site.

 

The maximum wind conditions encountered during ascent were 92.5 knots at 245° from true north at 46,670 feet, with a maximum wind shear of 0.0183 sec-1 at 46,750 feet.

 

Parking orbit conditions at insertion, 000:11:43.91 (S-IVB cutoff plus 10 seconds to account for engine tailoff and other transient effects), showed an apogee and perigee of 100.1 by 97.8 n mi, an inclination of 32.540°, a period of 88.16 minutes, and a velocity of 25,565.9 ft/sec. The apogee and perigee were based upon a spherical Earth with a radius of 3,443.934 n mi.

 

The international designation for the CSM upon achieving orbit was 1969-099A and the S-IVB was designated 1969-099B. After undocking at the Moon, the LM ascent stage would be designated 1969-099C and the descent stage 1969-099D.

 

 

Earth Orbit Phase

 

After inflight systems checks, made with extra care because of the two lightning strikes, the 341.14-second translunar injection maneuver (second S-IVB firing) was performed at 002:47:22.80. The S-IVB engine shut down at 002:53:03.94 and translunar injection occurred ten seconds later, at a velocity of 35,389.9 ft/sec after 1.5 Earth orbits lasting 2 hours 41 minutes 30.03 seconds.

 

 

Translunar Phase

 

For the first time, an Apollo vehicle was targeted for a high-pericynthion free-return translunar profile, a trajectory that would achieve satisfactory Earth entry within the reaction control velocity correction capability.

 

The major advantage of the new profile, termed a “hybrid” non-free-return trajectory, was the greater mission planning flexibility. This profile permitted a daylight launch to the planned landing site and a greater performance margin for the service propulsion system. The hybrid profile was constrained so that a safe return using the descent propulsion system could be made following a failure to enter lunar orbit.

 

 At 003:18:04.9, the CSM was separated from the S-IVB stage, transposed, and docked with the LM at 003:26:53.3. Onboard television, transmitted from 003:25 to 004:28, clearly showed the docking. The docked spacecraft were ejected from the S-IVB at 004:13:00.9. An
S-IVB auxiliary propulsion system evasive maneuver was performed at 004:26.40 and was also observed on television.

 

A ground command for propulsive venting of residual propellants targeted the S-IVB to go past the Moon and into solar orbit. However, due to an excessively long ullage engine burn, the distance of closest approach to the Moon prevented sufficient energy to allow the S-IVB to escape the Earth-Moon system, and it entered an elliptical orbit around Earth and the Moon. However, the objectives of not striking the spacecraft, Earth, or the Moon were achieved. The closest approach of the S-IVB to the Moon was 3,082 n mi at 085:48.

 

To insure that the electrical transients experienced during launch had not affected the LM systems, the commander and lunar module pilot entered the LM earlier than planned, at 007:20, to perform some of the housekeeping and systems checks. The checks indicated that the LM systems were satisfactory.

 

One midcourse correction was required during translunar coast, a 9.19-second, 61.8 ft/sec maneuver at 030:52:44.36. It placed the spacecraft on the desired hybrid, non-free-return circumlunar trajectory. Good quality television coverage of the preparations for this burn was received for 47 minutes, starting at 030:18.

 

A 56-minute television transmission began at 062:52. It provided excellent color pictures of the CM, intravehicular transfer, the LM interior, and brief shots of Earth and the Moon.

 

At 083:25:23.36, at an altitude of 83.91 n mi above the Moon, the service propulsion engine was fired for 352.25 seconds to insert the spacecraft into a lunar orbit of 170.20 by 61.66 n mi. The translunar coast had lasted 80 hours 38 minutes 1.67 seconds.

 

 

Lunar Orbit/Lunar Surface Phase

 

During the first lunar orbit, good quality television coverage of the surface was received for about 33 minutes, beginning at 084:00. The crew provided excellent descriptions of the lunar features while transmitting sharp pictures back to Earth.

 

Two revolutions later, at 087:48:48.08, a 16.91-second maneuver was performed to circularize the orbit at 66.10 by 54.59 n mi. On the next revolution, the LM crew transferred to the LM to perform various housekeeping chores and communication checks.

 

At 104:20, the commander entered the LM, followed by the lunar module pilot at 105:00 to prepare for descent to the lunar surface. The two spacecraft were undocked at 107:54:02.3 at an altitude of 63.02 n mi, followed by a 14.4-second separation maneuver at 108:24:36.8. At 109:23:39.9, a 29.0-second descent orbit insertion maneuver placed the LM into an orbit of 61.53 by 8.70 n mi.

 

The 717.0-second powered descent initiation ignition occurred at 7.96 n. mi. at 110:20:38.1, and landing occurred at 06:54:36 GMT (01:54:36 a.m. EST) on 19 November at 110:32:36.2 (the engine was shut down 1.1 seconds before landing). The spacecraft landed in the Oceanus Procellarum region (Ocean of Storms) at latitude 3.01239° south and longitude 23.42157° west. Approximately 103 seconds of engine firing time remained at landing.

 

One objective of the mission was to achieve a precision landing near the Surveyor III spacecraft, which had landed on 20 April 1967.[2] The LM landed just 535 feet from Surveyor.

 

During the next CSM revolution, the commander reported a visual sighting of the CSM orbiting overhead. On the following revolution, the command module pilot reported sighting the Surveyor III spacecraft as well as the LM northwest of Surveyor III.

 

Three hours after landing, the crew members began preparations for egress. The commander began to exit the hatch at 115:10:35. He deployed the modularized equipment stowage assembly which automatically activated a color television camera to permit his actions to be televised to Earth.

 

Before reaching the surface, the commander reported seeing Surveyor III about 600 feet away and also stated that the LM had landed about 25 feet from the lip of a crater. He was on the lunar surface at 115:22:22. His description indicated that the lunar surface was quite soft and loosely packed, causing his boots to dig in as he walked.

 

The lunar module pilot descended to the lunar surface at 115:51:50.

 

Shortly after the television camera was removed from its bracket on the LM, transmission was lost when the camera was pointed at the Sun. Lithium hydroxide canisters and the contingency sample were transferred to the LM cabin as planned. The S-band erectable antenna, and solar wind composition experiment were deployed, and the United States flag was erected at 116:19:31.

 

Except for minor difficulty removing the radioisotope thermoelectric generator fuel element from the cask, the removal of the Apollo Lunar Surface Experiments Package (ALSEP), transport, and deployment were nominal.

 

The ALSEP deployment site was estimated to be 600 to 700 feet from the LM. Shortly after deployment, the passive seismometer transmitted to Earth the crew members’ footsteps as they returned to the LM.

 

On the return traverse, the crew collected a core tube sample and additional surface samples. They entered the LM and the closed the hatch at 119:06:36. The first extravehicular activity period lasted 3 hours 56 minutes 3 seconds. The crew walked about 3,300 feet (1 km) and collected 36.82 pounds (16.7 kg) of samples.

 

At 119:47:13.23, the CSM performed a plane change maneuver of 18.23 seconds which changed the orbit to 62.50 by 57.60 n mi.

 

The second extravehicular activity period began at 131:32:45, after a seven-hour rest period. The crew first cut the cable and stored the inoperative LM TV camera in the equipment transfer bag for return to Earth and failure analysis. The commander then went to the ALSEP site to check the leveling of the lunar atmosphere detector. As he approached the instrument, it recorded a higher atmosphere, which was attributed to the outgassing of his suit.

 

Astronaut movement on the lunar surface was recorded on the passive seismometer and on the lunar surface magnetometer. In addition, the commander rolled a grapefruit-sized rock down the wall of Head Crater, about 300 to 400 feet from the passive seismometer. No significant response was detected on any of the four axes.

 

During the geological traverse towards Surveyor III, the crew members obtained the desired photographic panoramas, stereo photographs, core samples (two single and one double), an eight-inch-deep trench sample, lunar environment samples, and assorted rock, dirt, bedrock, and “molten” samples. They reported seeing fine dust buildup on all sides of larger rocks and that soil color seemed to become lighter as they dug deeper.

 

The crew photographed the Surveyor III and removed parts of it including the soil scoop. They reported that the Surveyor footpad marks were still visible and that the entire spacecraft had a brown appearance. The glass parts were not broken, only warped slightly on their mountings, and therefore were not retrieved.

 

After the return traverse, the crew retrieved the solar wind composition experiment after 18 hours 42 minutes exposure. The Apollo lunar surface close-up camera was used to take stereo pictures in the vicinity of the LM during the last few minutes of surface activity. Before reentering the LM, the crew members dusted each other off. The lunar module pilot entered the LM at 135:08, received samples, parts, and equipment from the commander, who then reentered at 135:20. Expendable equipment was jettisoned at 136:55, and the cabin was repressurized.

 

The second extravehicular activity period lasted 3 hours 49 minutes 15 seconds. The distance traveled was about 4,300 feet (1.3 km); 38.80 pounds (17.6 kg) of samples were collected. Crew ingress was complete at 135:22:00, thus ending the second human exploration of the Moon.

 

Mobility and portable life support system operation, as for Apollo 11, were excellent throughout both extravehicular periods. For the mission, the total time spent outside the LM was 7 hours 45 minutes 18 seconds, the total distance traveled was about 7,600 feet (2.3 km), and the collected samples totaled 75.73 pounds (34.35 kg, official total in kilograms as determined by the Lunar Receiving Laboratory in Houston). The farthest point traveled from the LM was 1,350 feet.

 

During the LM lunar surface stay, the S-158 lunar multispectral photography experiment was completed by the command module pilot in the CSM. In addition, photography of three desirable targets of opportunity was obtained. The areas were the Wall of Theophilus and two future Apollo landing sites, Fra Mauro and Descartes.

 

Ignition of the ascent stage engine for lunar liftoff occurred at 142:03:47.78. The LM had been on the lunar surface for 31 hours 31 minutes 11.6 seconds.

 

The 434-second burn was 1.2 seconds longer than planned and placed the spacecraft into an orbit of 51.93 by 9.21 n mi at 142:10:59.9. Several rendezvous sequence maneuvers were required before docking could occur three and a half hours later. A 41.1-second coelliptic orbit maneuver at 143:01:51.0 raised the orbit to 51.49 by 41.76 n mi. A 13.0-second constant differential height maneuver at 144:00:02.6 lowered the orbit to 44.4 by 40.4 n mi. A 26.0-second terminal phase initiate maneuver occurred at 144:36:26 and brought the ascent stage to an orbit of 60.2 by 43.8 n mi. Finally, the ascent stage made a 38.0-second maneuver at 145:19:29.3 to finalize the orbit at 62.3 by 58.3 n mi for docking with the CM at 145:36:20.2 at an altitude of 58.14 n mi. The two craft had been undocked for 37 hours 42 minutes 17.9 seconds. Good quality television was transmitted from the CSM for 24 minutes during the final portions of the rendezvous sequence.

 

After the transfer of the crew and samples to the CSM, the ascent stage was jettisoned at 147:59:31.6, and the CSM was prepared for transearth injection. The ascent stage was then maneuvered by remote control to impact the lunar surface. A 5.4-second maneuver was made at 148:04:30.9 to separate the CSM from the ascent stage, and resulted in an orbit of 62.0 by 57.5 n mi. An 82.1-second ascent stage deorbit firing was made at 149:28:14.8 at 57.62 n mi altitude. The firing depleted the ascent stage propellants, and impact occurred at 149:55:17.7, at a point estimated to be latitude 3.42° south and longitude 19.67° west, 39 n mi east southeast of the Apollo 12 landing site and 5 n mi from the target.

 

During the final lunar orbits, extensive landmark tracking and photography from lunar orbit were conducted. A 500 mm long-range lens was used to obtain mapping and training data for future missions.

 

Prior to transearth injection, a 19.25-second plane change maneuver at 159:04:45.47 altered the CSM orbit to 64.66 by 56.81 n mi. Following a 130.32-second maneuver at 63.60 n mi altitude at 172:27:16.81, transearth injection was achieved at 172:29:27.13 at a velocity of 8,350.4 ft/sec after 45 lunar orbits lasting 88 hours 58 minutes 11.52 seconds. Good quality television of the receding Moon and the spacecraft interior was received for about 38 minutes, beginning about 20 minutes after transearth injection.

 

 

Transearth Phase

 

A small midcourse correction was made at 188:27:15.8. It was a 4.4-second, 2.0-ft/sec maneuver, delayed one hour to allow additional crew rest. The final television transmission included the spacecraft interior and a question and answer period with scientists and members of the press. It began at 224:07 and lasted for approximately 37 minutes. The final midcourse correction, a 5.7-second, 2.4-ft/sec maneuver, was made at 241:21:59.7.

 

 

Recovery

 

The service module was jettisoned at 244:07:20.1, and command module entry (400,000 feet altitude) occurred at 244:22:19.09 at a velocity of 36,116.6 ft/sec, following a transearth coast of 71 hours, 52 minutes and 52.0 seconds. Following separation from the CM, the SM reaction control system was fired to depletion. However, no radar acquisition nor visual sightings by the crew or recovery personnel were made, and it was believed that the SM became unstable during the depletion firing and did not execute the velocity change required to skip out of Earth’s atmosphere into the planned high-apogee orbit. Instead, it probably impacted before detection.

 

Sea-state conditions were fairly rough, and the parachute system effected an extremely hard splashdown of the CM in the Pacific Ocean at 20:58:25 GMT (03:58:25 p.m. EST) on 24 November 1969. The force of the impact, about 15 g, not only knocked loose portions of the heat shield, but caused the 16 mm sequence camera to separate from its bracket and strike the LMP above the right eye. Mission duration was 244:36:25. The impact point was about 2.0 n mi from the target point and 3.91 n mi from the recovery ship U.S.S. Hornet. The splashdown site was estimated to be latitude 15.78° south and longitude 165.15° west.

 

After splashdown, the CM assumed an apex-down attitude, but was successfully returned to the normal flotation position in 4 minutes 26 seconds by the inflatable bag uprighting system.

 

Biological isolation precautions similar to Apollo 11 were taken. The crew was retrieved by helicopter and was aboard the recovery ship 60 minutes after splashdown. The crew immediately entered the mobile quarantine facility. The CM was recovered 48 minutes later. The estimated CM weight at splashdown was 11,050.2 pounds, and the estimated distance traveled for the mission was 828,134 n mi.

 

The mobile quarantine facility was offloaded from the Hornet in Hawaii at 02:18 GMT on 29 November, followed shortly by the CM. The mobile quarantine facility was loaded aboard a C-141 aircraft and flown to Ellington Air Force Base, Houston, Texas, where it arrived at 11:50 GMT. The crew entered the Lunar Receiving Laboratory two hours later.

 

The CM was taken to Hickam Air Force Base, Hawaii, for deactivation. Upon completion of deactivation, at 14:15 GMT on 1 December, the CM was flown to Ellington Air Force Base on a C-133 aircraft, and delivered to the Lunar Receiving Laboratory at 19:30 GMT on 2 December.

 

The crew was released from quarantine on 10 December. The CM was released soon after, and on 11 January was delivered to the North American Rockwell Space Division facility in Downey, California, for postflight analysis.

 

 

Conclusions

 

The Apollo 12 mission demonstrated the capability for performing a precision lunar landing, which was a requirement for the success of future lunar surface explorations. The excellent performance of the spacecraft, the crew, and the supporting ground elements resulted in a wealth of scientific information. The following conclusions were made from an analysis of post-mission data:

 

  1. The effectiveness of crew training, mission planning, and real-time navigation from the ground resulted in a precision landing near a previously landed Surveyor spacecraft and well within the desired landing footprint.

 

  1. A hybrid non-free-return translunar profile was flown to demonstrate a capability for additional maneuvering which would be required for future landings at greater latitudes.

 

  1. The timeline activities and metabolic loads associated with the extended lunar surface scientific exploration were within the capability of the crew and the portable life support systems.

 

  1. An ALSEP was deployed for the first time and, despite some operating anomalies, returned valuable scientific data in a variety of study areas.

 

[1] Conrad died 8 July 1999 in Ojai, CA, as a result of injuries sustained in a motorcycle accident.

[2] The COSPAR designation for Surveyor III was 1967-035A. The NORAD designation was 02756.

 

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