sition Experiment, reentered the LM, stowed all the collected samples, parts, and equipment in it, and repressurized the cabin. Lunar liftoff occurred at 9:26 a.m., e.s.t., November 20, concluding a total lunar stay of 31 hours, 31 minutes. No difficulty was encountered during rendezvous and docking with the CSM Yankee Clipper.

After the two astronauts transferred back to the CM, the LM ascent stage was jettisoned and deliberately impacted on the moon to provide a signal for the seismometer. It landed about 45 miles from the ALSEP at a speed of about 5,000 m.p.h. Scientists were surprised at the length of time (55 minutes) that vibrations continued to be recorded by the instrument after impact. On earth they would have registered for about 2 minutes on an earth-type seismometer. The CSM continued in orbit to achieve the final objective of the mission-obtaining photos of candidate future landing sites, Fra Mauro, Descartes, and Lalande.

The maneuvers for return to earth were all nominal, and the spacecraft splashed down in the Pacific at 3:58 p.m., e.s.t., on November 24. (Fig. 1-8.) The USS Hornet again made the recovery, as on the Apollo 11 mission. (Fig. 1-9.)

Post mission analysis indicated that the space vehicle triggered two lightning events soon after liftoff. At 36.5 seconds ground

elapsed time (GET), a cloud to ground discharge via the space vehicle occurred, and at 52 seconds GET a cloud to space vehicle to cloud discharge occurred. Most of the effects of these discharges were temporary and were corrected by the crew. The only permanent damage was to temperature and pressure measuring devices; their functions were performed by alternate means.

Guidance and control functions were excellent on this mission as on previous ones. Three of the four programed mid-course corrections during translunar trajectory were not required and were eliminated. On the earth-return trajectory, one of three planned corrections was eliminated.

Communications were very good throughout the mission except for occasional problems with the High Gain Antenna (HGA) and failure of the television camera after its removal from the MESA early in the first EVA. On several occasions communications with the CSM experienced some degradation because the HGA could not hold lock. Two special HGA tests were conducted during the transearth coast to attempt to resolve the anomaly. Results of these tests identified probable causes which the Agency was still investigating.

Performance of the Apollo 12 astronauts was outstanding throughout the mission in every way. Their fast thinking and alert reaction during the two lightning events quickly corrected the problem and dispelled the anxiety of ground observers.

Astronauts Conrad and Bean provided a detailed and comprehensive commentary on the lunar surface activities. They were initially cautious in their movements but eventually adapted well so that they were able to move about with relative ease and without tiring. Commander Conrad fell once but was able to recover easily from the prone position without assistance. He suggested, however, that a strap be added to facilitate buddy assistance. Both astronauts became somewhat thirsty during the extended EVA's in the lunar surface suits, but they were able to accomplish all lunar surface requirements. For Apollo 13, drinking water will be available to the astronauts during EVA.

Minimum medication was used by the crew, mostly decongestants to relieve stuffiness attributed to lunar dust transferred to the CM by the suits and gear used on the lunar surface. Astronaut Bean used sleeping pills before two of his rest periods following LM ascent stage separation. Skin cream was used by Commander Conrad for relief of a rash caused by his biomedical sensors. The crew was exceptionally enthusiastic during all phases of the mission, especially during EVA and television transmissions.

Apollo 13 Mission Summary

The Apollo 13 mission is scheduled to be launched in April 1970, with the Fra Mauro landing site as its objective. Flight hardware for this mission is to consist of the SA-508 launch vehicle, CSM-109 Command and Service Module, and LM-7 Lunar Module. This is to be the second of four flights planned in the H-series missions which use standard Apollo flight hardware for lunar exploration. The Apollo 13 astronauts are scheduled to be on the lunar surface about 35 hours, including two EVA periods. An ALSEP is to be placed on the Moon to record and transmit the important scientific data to Earth for up to a year.

Production, Development, and Test

Fifteen Saturn V vehicles were procured for the Apollo Program. Seven have been launched and two are scheduled for launch in calendar year 1970. One Saturn V, which is capable of placing 145 tons into low earth orbit or sending 50 tons to the moon, will launch the Apollo Applications Workshop, which has been renamed Skylab, in 1972; it had previously been scheduled for an Apollo lunar mission.

Production of the 15 Saturn V's was nearing completion. Some completed stages are to be placed in storage to await the dates when they must be delivered to KSC to meet the revised Apollo launch schedule. Procurement of additional Saturn V vehicles, beyond the 15 on order, was suspended. However, manufacturing techniques, test and checkout procedures, and associated data are to be preserved to provide the basic capacity for the resumption of Saturn V production.

The Command and Service Modules achieved all major objectives during the Apollo 11 and Apollo 12 missions as they had in Apollo 9 and 10. Only minor discrepancies occurred, presenting no hazard to crew or spacecraft. NASA was planning to modify the CSM to enable Apollo 16 and subsequent flights to support lunar landing missions of up to 16 days from launch to splashdown. Changes are to include an extra oxygen tank and an extra hydrogen tank. Also, configuration changes will make it possible to stow additional consumables, science experiments, and EVA equipment, and more lunar samples.

Other changes will make it possible to carry out scientific experiments while the CSM is in lunar orbit. Additions will include a Scientific Instrument Module (SIM) in one bay of the Service Module, appropriate displays and controls in the Command Module, and

wiring between the CM and the SM. EVA handrails are being added to the SM to facilitate retrieval of experimental data.

The Lunar Module also demonstrated operational maturity on the two lunar landing missions. However, it, too, will be changed for the extended time missions. Plans are to increase the lunar surface stay time to at least 54 hours and to carry both a Lunar Roving Vehicle (LRV) and an ALSEP.

To make room for the LRV, the LM batteries will be relocated. Additional batteries are also being provided. The LM descent stage propellent tanks are being enlarged to increase their capacity by some 1,200 pounds. This increase can either permit a greater payload or increase maneuver time during landing approach.

The astronauts will continue to use the A7L model spacesuit with changes to increase mobility and to allow for interface with the modified Portable Life Support System/Secondary Life Support System (PLSS/SLSS) and the LRV. (Fig. 1-10.)

The Apollo 11 model PLSS (the -6PLSS), which can be recharged at the LM, and its backup Oxygen Purge System (OPS) will be used through the Apollo 15 mission. The OPS is an emergency device to support the astronaut for 30 minutes in case of PLSS failure.

A modified PLSS, for use on Apollo 16 and subsequent missions, will have a 4-hour rating at a metabolic rate of 1,600 Btu/hour. (The metabolic rates experienced on the Apollo 11 and 12 missions averaged about 1,000 Btu/hour during EVA.) Increasing the oxygen charge pressure and capacity and enlarging the water tank will give the added capability. This model (designated the -7PLSS) will enable the astronauts to range farther from the landing site because they won't have to interrupt the EVA to visit the LM for recharge. To further support this range increase, an SLSS will replace the OPS, providing improved back-up capability. It will be 20 pounds heavier than the OPS but will occupy the same volume and will provide emergency life support for 11⁄2 to 2 hours in case of PLSS failure.

Cameras and other small orbital experiments are carried in the CM on all missions. On Apollo 16 through 19, a number of orbital experiments will be carried in the Service Module.

NASA approved additional experiments for flight on the CSM in lunar orbit to complement and extend knowledge gained from surface experiments. Examples of such experiments are those which can analyze lunar composition from lunar orbit by detecting radioactivity and measuring spectral reflectivity; radar sounders