SP-368 Biomedical Results of Apollo






Richard S. Johnston
Wayland E. Hull
Lyndon B. Johnson Space Center




[9] The manned Lunar Landing Program was the most complex and largest single scientific exploration undertaken in the history of mankind. On the 20th of July, 1969, Neil A. Armstrong and Edwin E. Aldrin, Jr. set foot on the moon. For two hours and 21 minutes, the two men, first cautiously and then boldly, negotiated their way about the lunar terrain. They demonstrated to themselves and to the 500 million people viewing their triumph throughout the world that movement on the lunar surface was a relatively easy and even enjoyable thing. They set up scientific experiments and collected rock and soil samples for return to Earth for subsequent analysis.

The Apollo Program ultimately placed twelve men on the lunar surface. It was a major national event. During peak activity, more than 400 000 people and 20 000 companies were involved. Table 1 summarizes the manned Apollo flights, listing the crews, landing sites, launch dates, and mission durations. This chapter precedes the discussion of the biomedical results of the Apollo missions in order to give the reader some historical perspective from which to view the Apollo findings. The Apollo systems and highlights of each mission are presented.


The Apollo Spacecraft


The Apollo spacecraft launch and lunar landing configurations are pictured in figure 1. The launch configuration of the assembly was 15 meters (43 feet long and consisted of five major segments: Launch Escape System, Command Module, Service Module, Lunar Module Adapter, and Lunar Module.


The Launch Escape System

The Launch Escape System consisted of the 10-meter (33-foot) tower weighing 3629 kg (3000 lb) and a solid rocket motor 4.72 m (15.5 ft) providing 66 675 kg (147 000 lb) of thrust. The Launch Escape System provided a means for escape during....


10] Table 1

Summary of Apollo Manned Flights

Apollo Missions


Lunar Landing site

Mission Description

Launch Date

Mission Duration (hrs)

Total Time

Lunar Surface



Schirra, Cunningham, Eisele


Earth orbit test of Command Module

9 -11-68





Borman, Lovell, Anders


First manned circumlunar flight






McDivitt, Scott, Schweickart


Earth orbit test of Lunar Module




First time spacecraft separated inflight



Stafford, Cernan, Young


Circumlunar mission




Lunar Module separation and descent engine firing



Armstrong, Collins, Aldrin

Sea of Tranquility

First manned lunar landing




First returned lunar samples



Conrad, Gordon, Bean

Ocean of Storms

Second lunar landing




First Apollo Lunar Surface Experiment Package (ALSEP)



Lovell, Swigert, Haise


Aborted lunar landing mission due to oxygen tank failure






Shepard, Roosa, Mitchell

Fra Mauro

Third lunar landing




Explored lunar highlands



Scott, Worden, Irwin

Hadley Rille

First lunar rover used




Geological sampling of the Apennine Mountain base



Young, Mattingly, Duke


Geological sampling from volcanic areas of moon






Cernan, Evans, Schmitt

Taurus- Littrow

Exploration of area to provide information about formation and history of moon









[11] ...countdown or in the first 100 seconds of the lift-off sequence, should a fire or other abort situation develop. Upon activation, the escape tower would lift the spacecraft about 1.6 km (1 mile) clear of the launch pad and rocket. Descent would be provided by the main parachute system.


Apollo spacecraft at launch

Figure 1. Apollo spacecraft - Perspective drawing.

Figure 1. Apollo spacecraft at launch (left); perspective drawing (right).


Command Module

The basic structure of the Command Module (CM) was a pressure vessel encased in a heat shield. The Module was conical shaped, measuring 3.48 m long (11.5 ft), with a base diameter of 3.91 m (12 ft, 10 in.). The Command Module consisted of a forward compartment containing two reaction control engines and parachutes used for the Earth landing system. The crew compartment or inner pressure vessel contained crew accommodations, controls and displays, and other spacecraft systems. The aft compartment housed ten reaction control engines, propellant tanks, helium tanks, water tanks, [12] and the Command Service Module umbilical cable. The habitable volume of the crew compartment was 5.95 m3 (210 ft3).

Within the Command Module the Commander, who operated the flight controls, was positioned at the left; the Command Module Pilot, who was responsible for guidance and navigation! was couched in the center; and the Lunar Module Pilot, responsible for management of subsystems, was on the right. The couches faced the display console.

The atmosphere of the Command Module was planned to be 100 percent oxygen at 34 x 103N/m2 (5 psia) and was altered as a result of a spacecraft fire in 1967 to a 60/40 oxygen/nitrogen mixture at 103 x 103N/m2 (15 psia) at lift-off. The cabin pressure was allowed to equilibrate at 5 psia as altitude was reached. The atmosphere was enriched with oxygen until the breathing gas approached 100 percent oxygen. Oxygen was used in flight to furnish breathing gas as well as to make up for spacecraft leakage, resulting in an oxygen-rich atmosphere. The thermal control portion of the environmental control system maintained the cabin temperature of the spacecraft in a comfortable range of 294.15° to 297.15°K (21° to 24°C). The Command Module contained two hatches, one at the side for entry and one at the top for use when the spacecraft was docked with the Lunar Module. Five observation windows permitted extensive outside viewing and photography during the missions.


Service Module

The Service Module (SM) was a cylindrical structure, 3.91 m in diameter (12 ft, 10 in.) by 7.49 m long (24 ft, 7 in.). This part of the spacecraft contained the main propulsion system and provided stowage for most of the consumable supplies.

The Service Module remained attached to the Command Module on the flight to the moon. During the return flight, separation occurred just before Earth atmosphere reentry. The service propulsion system was used for midcourse maneuvers and to reduce the velocity of the spacecraft to enter lunar orbit.

A Scientific Instrument Module (SIM) was carried in the Service Module for the first time on the Apollo 15 mission. The SIM accommodated eight experiments utilizing spectrometers, panoramic and mapping cameras, a laser altimeter, and a subsatellite for injection into lunar orbit. Figure 2 shows schematics and cutaway diagrams of the Command and Service Modules.


Lunar Module Adapter

This segment of the spacecraft served as a smooth aerodynamic enclosure for the Lunar Module and provided the attachment for the Command Module to the launch vehicle. The Lunar Module was extracted from the Adapter shortly after the spacecraft left Earth orbit.


The Lunar Module

The Lunar Module (LM) was a two-stage vehicle with a vertical dimension of 6.985 m (22 ft, 11 in.). The diagonal width between landing gear was 9.45 m (31 ft). The Lunar Module transported astronauts from the lunar orbiting Command Module to the lunar surface, provided living quarters and a base of operations on the moon, and returned the [13] crew to the Command Module in lunar orbit. The Lunar Module ascent and descent stages are shown in figure 3. The two stages were joined by four explosive bolts and umbilicals. The ascent stage functioned as a single spacecraft for rendezvous and docking with the Command Service Module at the conclusion of lunar surface missions. Because it was designed to fly only in the vacuum of space, the LM was incapable of reentering Earth's atmosphere.


Figure 2. Diagram of Apollo Command and Services Modules.

Figure 2. Diagram of Apollo Command and Services Modules.


The ascent stage was made up of three main sections: the crew compartment, the midsection, and the aft equipment bay. The crew compartment and midsection were pressurized. The habitable cabin volume was 6.7 m3 (235 ft3). The ascent stage was 3.76 m long by 4.29 m in diameter (12 ft, 4 in. x 14 ft, 1 in.). Figure 4 (A and B) shows the interior of the Lunar Module cabin.

The descent stage was the unmanned portion of the Lunar Module. It supported the ascent stage for the landing on the lunar surface, and contained the propulsion system...



Figure 3. Lunar Module ascent and descent stages.

Figure 3. Lunar Module ascent and descent stages.


Figure 4. Lunar Module cabin interior.

Figure 4. Lunar Module cabin interior.


[16]... used to slow the spacecraft for a safe landing on the moon. During descent, four landing gear struts were released from a folded stowage position to form the landing gear for the vehicle. Each of the struts was filled with crushable aluminum honeycomb to absorb the landing impact Foot pads at the ends of the legs contained sensing probes which signaled the crew to shut down the descent engine upon contact with the lunar surface. The landing radar provided information pertaining to the altitude and velocity of the Lunar Module relative to the lunar surface. Four bays surrounded the descent engine and contained the propellant tanks, the Modularized Equipment Stowage Assembly (TV equipment, lunar sample containers, and portable life support systems), the Lunar Roving Vehicle (LRV), and the Apollo Lunar Surface Experiment Package (ALSEP).

Lunar Roving Vehicle. The Lunar Roving Vehicle was used for the first time with great success on the Apollo 15 mission. Figure 5 shows the vehicle beside the Lunar Module. The lunar payload capacity was several times the vehicle's Earth weight. The vehicle propulsion system was battery operated, each wheel of the vehicle being individually driven by a one-quarter horsepower electric motor. The operational life was 72 hours during the lunar day, enough to easily provide a 9.65 km (6 mile) exploration radius. It was transported to the moon folded tightly into a storage quadrant of the Lunar Module and was deployed by pulling two nylon operating tapes and removing release pins. The Rover was then unfolded for use.


Figure 5. Apollo 16 Lunar Module and Lunar Roving Vehicle.

Figure 5. Apollo 16 Lunar Module and Lunar Roving Vehicle.


Figure 6 is a diagram of the LRV. The T-shaped hand controller permitted the vehicle to be operated by either of the two astronaut passengers. The LRV could climb and descend slopes of 25 degrees inclination. It was equipped with a dead-reckoning [17] navigation system which the crew used to find their way back to the Lunar Module from long explorations when out of sight of the home base.


Figure 6. Diagram of the Lunar Roving Vehicle.

Figure 6. Diagram of the Lunar Roving Vehicle.


The LRV doubled traverse distance during lunar expeditions. A remotely controlled television camera mounted on the vehicle enabled Mission Control and the public to observe activities carried out during its use. The Lunar Communications Relay Unit was carried on the LRV to provide for voice communications and transmission of portable life support system data and biomedical data. In addition, the system provided color television transmission which was observed by the mission controllers and, at certain times, by the public The Communications Relay Unit was a self-contained, battery powered system, stowed in the Lunar Module descent stage at launch and placed on the LRV for lunar surface operations. The television camera was mounted on a motor driven gimbal system, controlled from the Earth to direct the camera at points of interest and at the crew during exploration. At the conclusion of lunar surface missions, the television system provided pictures of the breakaway of the ascent stage from the descent stage and the rising of the ascent stage toward lunar orbit.

Apollo Lunar Surface Experiment Package. The Apollo Lunar Surface Experiment Package (ALSEP) was a system of scientific instruments carried to the moon in the Lunar Module and set up on the lunar surface by Apollo crews. Using a self-contained power supply and communications equipment, each ALSEP collected and transmitted to Earth [18] scientific and engineering data for several years following astronaut departure from the lunar surface.

Because of power and weight limitations, no single flight could carry all the ALSEP experiments. Certain elements of the total program were assigned to Apollo flights 12 through 17. On the Apollo 15 and 17 missions the experiment package included a particles and fields subsatellite. The subsatellite was a 76.2 cm (30 in.) tall, 47.6 kg (106 lb), solar-cell-powered spacecraft which was inserted into lunar orbit from the Service Module. It carried a magnetometer, particle detector instruments, and a transmitter, all of which were operated from Earth to collect and relay data on the extralunar environment.


Apollo Space Suits and Portable Life Support System


The space suit used by the crew in the lunar exploration program had its roots in concepts reaching as far back as the late 19th Century. Jules Verne was probably the first to conceive of pressure suits for protection against reduced barometric pressures of higher altitudes. In 1872, he described closed circuit, extravehicular pressure suit operation for flight around the moon. In August 1934, Wiley Post made the first aircraft flight in a pressure suit. The suit was constructed of two layers, an inner rubber bag designed to contain gas under pressure and an outer cloth fabric to maintain the desired suit shape. Following World War II, both the Air Force and Navy continued development of space suits.

The space suit worn by Mercury astronauts was similar to pressure suits used in high altitude military jet aircraft flight. The Project Mercury suit consisted of an inner layer of neoprene-coated nylon fabric and a strain-resistant layer of aluminized nylon fabric. The aluminized coating was used to reject increased cabin heat during reentry. Biomedical sensors were contained inside the suit to monitor body temperature, electrocardiogram, blood pressure, and respiration rate. Urine was collected in a special bag within the suit. The breathing gas, oxygen, was supplied to a fitting at the front of the torso and was then distributed throughout the interior of the suit to be discharged into the helmet in such a way as to sweep exhaled moisture from the visor portion of the helmet. The suit weighed approximately 9.1 kg (20 lb). The Mercury suit was to be used as an emergency backup to the spacecraft pressurization system in case of cabin system failure. A high degree of mobility was not a requirement because of the restrictive volume of the Mercury space capsule.

Because Project Gemini was to involve extravehicular activity, the structural requirements for the space suit changed. Additional layers were added to afford the needed protection in free space operations. The Gemini suit consisted of an outer layer of temperature resistant nylon, a layer of "link-net" to provide pressurized mobility and to control ballooning of the suit, a pressure-tight layer of neoprene-coated nylon, and an inner aluminized layer of nylon for thermal and micrometeoroid protection. A removable visor was added to the helmet to protect the inner visor from impact damage and to provide additional protection from the increased levels of ultraviolet radiation encountered outside the Earth's atmosphere. As before, the breathing gas was 100 percent oxygen and the suit was worn for the entire duration of the mission.

[19] The Gemini flights gave mission planners confidence in spacecraft integrity. Micrometeoroids proved less of a menace to spacecraft integrity than some individuals had feared. As a consequence, Apollo astronauts did not wear pressure suits through all of the mission, donning them only for critical spacecraft operations such as launch, rendezvous, and docking. The Apollo suit was similar to the Gemini suit, with a multilayered construction. The outer suit layer of Teflon-coated fabric was woven of Beta glass. Beneath this layer was a restraint layer of Nomex ;and convoluted joints to restrain internal pressure and maintain the shape of the suit. The next layer below was a neoprene-coated nylon pressure bladder; and the final layer was a high-temperature resistant nylon liner which replaced an earlier simple comfort layer. As in earlier suits, 100 percent oxygen was supplied through a fitting in the front of the torso. Communications and biomedical data lines passed through the suit by a multiple circuit electrical connection on the front of the suit. The Apollo suit assembly weighed about 16.15 kg (35.6 lb).

Apollo astronauts who performed EVA were provided with a self-contained Portable Life Support System (PLSS) carried in a backpack unit. This permitted operation at great distances from the spacecraft. The system supplied oxygen for pressurization and metabolic consumption, and cooling water for operation of a liquid cooling undergarment. The portable life support system also contained communications and telemetry equipment, and a transmitter power supply. Mounted atop the PLSS was an oxygen purge system which provided a contingency supply of gaseous oxygen lasting 40 minutes when activated. The PLSS was a part of the Extravehicular Mobility Unit (EMU), which consisted also of an extravehicular space suit, a liquid cooling garment, an oxygen purge system, a lunar extravehicular visor assembly, and a special lunar overshoe.

The Apollo Extravehicular Mobility Unit gave man a completely self-contained mode for moving about on the moon for a fixed period of time. The system worked extremely well. There were no failures experienced with the suit on the lunar surface. The prospect, however slim, of suit failure was extremely unnerving because it was not possible to build the same degree of redundancy into certain parts of the space suit as could be built into the spacecraft. Only one pressure bladder layer could be provided because redundant layers would tend to make the space suit excessively stiff and hard. The total success of the Apollo space suit system must be credited both to excellence in design and meticulous testing.


Unmanned Missions


The way was paved for the manned Apollo Program by a series of unmanned flights. The early flights were made by Surveyor spacecraft that were launched on Atlas-Centaur launch vehicles. The first Surveyor flight was launched on May 30, 1966, from Cape Canaveral, Florida, on a direct-ascent lunar trajectory. The Surveyor Flights validated several critical aspects of advanced soft landing techniques for later use by Apollo. They provided essential data on the compatibility of the Apollo design with conditions encountered on the lunar surface, and yielded information about the topography of the lunar surface and its thermal environment. In addition to the Surveyor flights, three [20] Lunar Orbiter flights produced medium and high resolution photographs over broad areas of the moon to aid in site selection for the Apollo manned landing program (see figure 7).


Figure 7. First photograph of Earth from the vicinity of the moon; taken by Lunar Orbiter 1, 25 August 1966.

Figure 7. First photograph of Earth from the vicinity of the moon; taken by Lunar Orbiter 1, 25 August 1966.


Apollo/Saturn 201

The first Apollo/Saturn mission employed an unmanned Apollo spacecraft on a suborbital flight that gathered data for qualifying the Apollo Command Module heat shield, the Service Module prime propulsion system, and the first flight of the Saturn l-B launch vehicle. The spacecraft was flown 8047 km (5000 miles) in a suborbital flight on February 26, 1966. The engines of the upper stage of the launch vehicle, the Saturn lV-B, were fired in flight for seven minutes to demonstrate the J-2 liquid hydrogen/liquid oxygen engine. The service propulsion system engine also was fired twice to demonstrate engine restart capability. These two engine firings were used to propel the spacecraft to a reentry velocity of 8071 meters/second (26 481 feet/second) which is 299 meters per second (981 feet/second) above orbital velocity. By achieving this velocity, the capability of the Command Module heat shield to withstand Earth reentry heating was demonstrated. Recovery of the spacecraft was normal, and all mission objectives were accomplished.


[21] Apollo/Saturn 203

Apollo/Saturn 203 served as an unmanned flight test of the uprated Saturn I launch vehicle. An Apollo spacecraft was not carried in this mission; instead, the upper stage of the launch vehicle was mounted with a nose cone. This large assembly was 28.04 m (92 ft) long and weighed 26 535 kg (58 500 lb). It was placed into Earth orbit on July 5, 1966. During the first four orbits, liquid hydrogen studies were conducted to determine the behavior of cryogenic liquids in the absence of gravity. Again, all mission objectives were accomplished.


Apollo /Saturn 202

This unmanned suborbital mission was used to qualify the Command and Service Modules and the uprated Saturn I launch vehicle for manned flight. The spacecraft was launched on August 25, 1966, from the Kennedy Space Center and traveled approximately 27 350 km (17000 miles) to land in the Pacific Ocean. The Service Module propulsion system was fired for 215 seconds to place the spacecraft into a trajectory to provide a steep angle/high beating reentry. For the first time, the Apollo guidance and navigation system provided the onboard control of spacecraft attitudes and trajectory. This system automatically controlled the propulsion system burns and guided the spacecraft through entry and landing.


Apollo 4

On November 9, 1967, an unmanned Earth-orbital flight test of the Saturn V launch vehicle and Apollo Command Module was undertaken. The three stages of the Saturn V placed into orbit a record payload of over 127 066 kg (280 000 lb). Flawless performance of the launch vehicle on its first unmanned flight provided the U.S. with a major operational capability for orbiting large payloads. The Saturn IV-B engine was fired twice to place the Command and Service Modules into a 18 092 km (9769 nautical miles) apogee at the end of the second orbit. The Saturn IV-B was separated and the service propulsion system engine was burned twice to accelerate the Command Module to a lunar return velocity of 10 973 meters/second (36 000 feet/second). The mission qualified the Command Module ablative heat shield to withstand Earth reentry from lunar return speeds. Apollo 4 was the first man-made object to withstand reentry into the Earth's atmosphere at such am extreme velocity.


Apollo 5

Apollo 5 was an unmanned flight and the first flight test of the Lunar Module. The launch date was January 22, 1968. The primary objective of the flight was to test the Lunar Module propulsion systems and the abort staging function for manned flight. The test for both the descent and ascent stage propulsion systems was successful, except for one descent engine shutdown during the first firing. The abort sequencing was successfully demonstrated during the second and third descent engine firings. This flight test qualified the Lunar Module for manned Earth-orbital flights.


[22] Apollo 6

The last of the unmanned Apollo missions was a test of the Saturn V launch vehicle. On April 4, 1968, the Apollo Command and Service Modules and the Saturn IV-B were placed into an Earth orbit. Approximately two minutes after lift-off and during the first stage boost, a major structural anomaly occurred in the spacecraft/launch vehicle adapter. Oscillations induced by the launch vehicle in excess of spacecraft design criteria were apparently the cause of the abrupt changes manifested in strain, vibration, and acceleration measurements in the spacecraft and adapter. The S-ll second stage engines shut off early and the Saturn IV-B stage engines were required to place the spacecraft into orbit. Upon investigation, improper installation of signal wires was found to be the cause of the premature engine shutdown. The Service Module propulsion system was fired for seven minutes to place the spacecraft into a trajectory with a 19 312 km (12 000 mile) apogee and a high speed Earth reentry. The reentry velocity was 10 006 meters/second (32 830 feet/second) which was approximately 1219 meters/second (4000 feet/second) less than planned The test provided additional qualification data for the Command Module heat shield. Based on the results of the unmanned flight program, Apollo moved to the manned space flight phase.


Manned Missions


Apollo 1 (Apollo 204)

The first manned Apollo flight was scheduled for late February 1967, but because of am unanticipated tragedy, was delayed until October 1968. The tragedy occurred on January 27th when the three-man crew for Flight 204* died instantly after a flash fire swept through the Apollo spacecraft. Killed in the accident on Cape Canaveral's Pad 34 (then, Cape Kennedy) were Virgil I. Grissom, Commander; Edward H. White, Command Module Pilot; and Roger B. Chaffee, Lunar Module Pilot. Virgil Grissom was one of the seven original Mercury astronauts, Edward White was the first American to "walk" in space during the Gemini Program, and Roger Chaffee was preparing for his first space flight. The accident occurred at 6:31 p.m. Eastern Standard Time during the first major rehearsal for the mission.

The cause of the Apollo 204 fire has never been positively identified. For a detailed description of the accident and its investigation, the reader is referred to the Report of the Apollo 204 Review Board to the Administrator, National Aeronautics and Space Administration, 5 April 1967, available from the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

As a result of the 204 fire, alterations were made in the spacecraft systems, in the cabin atmosphere, and in materials used within the spacecraft to maximize the resistance to fire.

The impact of the fire on the medical program per se was threefold. After the addition of nitrogen gas to the cabin atmosphere, careful observations had to be made to determine if there might be some physiological effects as a result of the small amount of [23] nitrogen remaining. However, no clear-cut effect could be identified. As an added safety precaution after the fire, vital signs of all crewmen were monitored during the launch period, whereas only one had been followed previously. Finally, the inflight medical experiments program planned for earlier Apollo flights was eliminated. Program energies and resources had to be directed exclusively toward the task of getting man to the moon safely and safely returning him to Earth. The accident brought a renewed dedication and purposefulness to the goal of landing an American on the moon before the end of the decade of the '60s.


Apollo 7

Apollo 7 was the first manned orbital flight test of the Apollo spacecraft. On October 11, 1968, a Saturn I-B launch vehicle placed the Command Module and Service Module into a near-Earth orbit of eleven days duration. The crewmembers were Walter M. Schirra, Jr., Commander; Donn F. Eisele, Command Module Pilot; and R. Walter Cunningham, Lunar Module Pilot. The primary goal of Apollo 7 was to demonstrate crew and spacecraft performance. The mission, unlike manned orbital flights on previous programs, involved little scientific experimentation.

Prior to separation of the Command and Service Modules from the Saturn IV-B launch stage, the crew manually flew the spacecraft/Saturn IV-B combination. The spacecraft was then separated from the Saturn IV-B and a simulated transposition and docking maneuver was completed. This maneuver simulated the spacecraft operation required during a lunar mission to couple the Command Module with the Lunar Module, and to separate the Lunar Module from the Saturn IV-B. Later, the Apollo 7 crew successfully maneuvered the spacecraft for a re-rendezvous with the Saturn IV-B. Eight planned maneuvers were successfully completed using the Service Module propulsion system.

In general, all spacecraft subsystem performance was excellent. Real-time television images were transmitted by the crewmen to Earth. These showed spacecraft interior activities and views of the Earth. The crew suffered head colds during the mission which hampered some spacecraft operations. For the first time, U.S. astronauts did not wear space suit helmets during entry into the Earth's atmosphere.

All mission and scientific objectives were met by the flight of Apollo 7, qualifying the Command and Service Modules for eleven-day manned missions. One of the most significant findings of this flight was that the volume of the Command Module proved to be quite adequate for a three-man crew operating in weightlessness. The crew enjoyed relative comfort compared with the conditions prevailing in the Gemini spacecraft.

The flight of Apollo 7 ended with a splashdown in the Atlantic Ocean 260 hours and 9 minutes after launch from Kennedy Space Center (figure 8). The crew was retrieved by helicopter and the spacecraft was later taken aboard the USS Essex. The successful flight of Apollo 7 represented a major milestone in the U.S. manned space flight program.

The Apollo 7 mission and all subsequent manned missions are described in detail, including biomedically significant findings, in the Apollo Mission Report series. These documents are available through the Scientific and Technical Library, Lyndon B. Johnson Space Center, Houston, Texas.



Figure 8. Apollo 7 spacecraft following splashdown.

Figure 8. Apollo 7 spacecraft following splashdown.


Apollo 8

Man's first lunar orbital flight began on December 21, 1968, when a Saturn V launch vehicle placed the Apollo 8 Command and Service Modules in Earth orbit. Frank Borman was the Commander; James A. Lovell, Jr., the Command Module Pilot; and William A. Anders, the Lunar Module Pilot. The Apollo 8 crew was the first to be launched by the 2722 metric ton (3000 ton) Saturn V. The crew checked out the spacecraft, and, after approximately three hours in Earth orbit, the Saturn IV-B stage was fired for approximately five minutes to accelerate the spacecraft to an Earth-gravity escape velocity of 40 233 km/hr (25 000 mph) to begin its 370 149 km (230 000 mile) coast to the moon. Following the translunar injection maneuver, the Apollo spacecraft was separated from the Saturn IV-B stage.

During the transearth period, the crew transmitted live television pictures of the spacecraft interior and of the Earth The spacecraft velocity decreased during the coast period due to the Earth's gravitational force. As the spacecraft neared the moon, it was accelerated by the pull of lunar gravity, and the Service Module propulsion system was fired to slow the vehicle to 6035 km/hr (3750 mph) and place it in lunar orbit.

Apollo 8 achieved lunar orbit on Christmas Eve. Lunar operations lasted for ten orbits, at am altitude of 96.56 km (60 miles) above the lunar surface. The crew transmitted television pictures of the lunar surface, studied potential Apollo landing sites, and took excellent photographs, including those shown in figure 9 (A & B). They filmed and photographed the far side of the moon, which had never before been seen by man.



Figure 9. Photographs of the Iunar landscape taken by the crew of Apollo 8.

Figure 9. Photographs of the lunar landscape taken by the crew of Apollo 8.


[26] After approximately twenty hours of lunar orbital operations, the Service Module propulsion system engines were fired for three minutes to accelerate the spacecraft to a velocity sufficient to escape from the moon's gravitational force. The transearth coast period lasted for approximately 63 hours. The spacecraft landed in the Pacific Ocean, where the crew and spacecraft were recovered by the USS Yorktown, just eleven seconds earlier than the time computed in the flight plan months before the mission. The Apollo 8 mission had lasted six days.

With only minor discrepancies, the spacecraft and systems functioned with precision throughout the mission. The accuracy of the onboard guidance and navigation control system demonstrated that astronauts could return safely from the moon without the aid of Earth-based tracking systems. Crew performance was excellent, despite some minor illness early in the mission. All mission objectives were met. Apollo 8 qualified the launch vehicle and spacecraft for lunar flight. The crew provided valuable information on the lunar surface, and demonstrated the ability to recognize surface features needed in lunar landing navigation. The Apollo 8 crew received this Nation's highest recognition, including an appearance before a joint session of the United States Congress. The flight of Apollo 8 was heralded as an odyssey without precedent in man's history.


Apollo 9

Apollo 9 was the first manned flight with the Lunar Module and the first mission employing two manned spacecraft. The flight lasted ten days. The crewmen were James A. McDivitt, Commander; David R. Scott, Command Module Pilot; and Russell L. Schweickart, Lunar Module Pilot. The objectives of this mission were to evaluate the Lunar Module under space flight conditions, perform an extravehicular contingency transfer from the Lunar Module to the Command Module, and demonstrate the capability to fly the two spacecraft on lunar landing type trajectories to achieve rendezvous and docking.

The spacecraft was launched into Earth orbit by a Saturn V launch vehicle on March 3, 1969. The Command and Service Modules were separated from the Saturn IV-B stage which contained the Lunar Module (figure 10) The Command and Service Modules were turned around to face the Lunar Module and docked with it. The two spacecraft then separated from the Saturn IV-B stage. For the next several days, combined spacecraft operations were conducted, and Russell Schweickart carried out an abbreviated extravehicular mission on the fourth day. The space walk was delayed because Schweickart suffered nausea and vomiting early in the flight. He, along with the other two crewmen, suffered from colds during the mission. In place of the space walk, he climbed out of the Lunar Module and stood on its porch for approximately 47 minutes. On the fifth day of the mission, McDivitt and Schweickart separated the Lunar Module from the Command Module and, using both the descent and ascent propulsion systems, flew a simulated lunar landing and ascent trajectory while Scott remained in the Command Module. The vehicles were separated for about four hours at distances up to 351.9 km (190 nautical miles). When the two craft were 182 km (113 miles) apart, Schweickart and McDivitt jettisoned the descent stage to simulate takeoff from the lunar surface. They fired the ascent engine and the two spacecraft rendezvoused and docked as planned. For the remainder of the ten-day mission, the crew performed landmark tracking and photographic tasks.



Figure 10. Artist's conception of Command/Service Module and Lunar Module separating from the Saturn IV-B third-stage rocket.

Figure 10. Artist's conception of Command/Service Module and Lunar Module separating from the Saturn IV-B third-stage rocket.


The spacecraft splashed down in the Atlantic Ocean only 4.8 km (three miles) from recovery aircraft carrier, the USS Guadalcanal. The recovery went extremely well.

The performance of both the spacecraft and its subsystems was nearly flawless, and mission objectives were met. The Apollo 9 mission qualified the launch vehicle, the lunar landing spacecraft, the portable life support system (PLSS) backpack, and the flight control techniques designed for manned lunar landing flights.


Apollo 10

Apollo 10 was the last planned manned lunar orbital flight. The Apollo 10 mission lasted eight days and was, in effect, a dress rehearsal for the manned lunar landing. The flight successfully demonstrated the complete Apollo spacecraft system, including Lunar Module descent to within 14.4 km (47 400 ft) of the lunar surface. The crewmembers were Thomas P.Stafford, Commander; John W.Young, Command Module Pilot; and Eugene A. Cernan, Lunar Module Pilot. The launch date was May 18, 1969. After two and one-half hours in Earth orbit following launch by the Saturn V vehicle, the Saturn IV-B second stage was injected to place the spacecraft on a translunar trajectory.

The mission plan closely followed the Apollo 11 lunar landing flight plan. The crewmen separated the Command Module from the Saturn IV-B stage, rotating the craft 180 degrees and docking it with the Lunar Module which was extracted from the Saturn IV-B. The docking operations were viewed via color television that was [28] transmitted to Earth. The docked spacecraft were placed in lunar orbit and thirty-two revolutions were made around the moon by the Command and Service Modules at a distance of 97 km (60 miles) from the lunar surface.

On the fourth day of the mission, with Astronaut Young in control of the Command Module, Stafford and Cernan undocked the Lunar Module and made a simulated landing in the LM by descending to within 14 km (9 miles) of the lunar surface. The descent stage propulsion system was used to slow the Lunar Module to begin the descent toward the moon. The ascent engine was fired to place the Lunar Module into a trajectory to rendezvous and dock with the lunar orbiting Command Module. After eight hours of separation, the two spacecraft docked successfully, and the Lunar Module crew reentered the Command Module for the return trip to Earth.

The Apollo 10 mission accomplished its primary aim of providing quantitative operational data on the spacecraft and the experience in lunar landmark tracking needed to ensure a high probability of success for the lunar landing mission. The Apollo 10 mission completed final qualification of the Lunar Landing Module by means of a rigorous duplication of all aspects of the Apollo 11 mission profile, with the exception of an actual landing.


Apollo 11

On July 16, 1969, Apollo 11, the first lunar landing flight, was launched from Kennedy Space Center, Florida, before an onsite audience of over one million people. The mission Commander was Neil A. Armstrong, the Command Module Pilot was Michael Collins, and the Lunar Module Pilot was Edwin E. Aldrin, Jr.

The lunar landing was achieved by a method established in July of 1962. The method ultimately chosen, demonstrated as feasible by the Apollo 10 mission, was a lunar orbit rendezvous. This technique met the constraints of time, funds, safety, and technology. The scheme was recommended to NASA management by John C. Houbolt, an aeronautical engineer at the NASA Langley Research Center. In Houbolt's scheme, a Saturn V rocket would launch the Apollo craft, a three-man crew, and a lunar landing craft on a lunar orbital course. Once in orbit, two men would transfer to the lunar landing spacecraft, undock from the mother ship, and descend to the lunar surface. After the lunar visit, the crew would launch and rendezvous with the Command ship in lunar orbit, leave the landing vehicle in orbit, and return to Earth. The selection of the method for accomplishing the lunar landing was of great importance for the design of the spacecraft and the launch vehicle. Lunar orbit rendezvous was ultimately selected based on a tradeoff which considered launch weights and other operational considerations.

Three days after the launch to the moon, the Apollo 11 spacecraft was slowed by the Service Module propulsion system from a velocity of 10139 km/hr (6300 mph) to 6437 km/hr (4000 mph). On Saturday, July 19, 1969, the spacecraft achieved lunar orbital insertion. The orbit ranged from 86.6 by 105.7 km (53.8 by 65.7 miles) from the lunar surface. On Sunday, July 20th, with Michael Collins remaining behind in the Command Module, Columbia, Astronauts Armstrong and Aldrin entered the Lunar Module, Eagle. On the 13th lunar orbit, the spacecraft separated and the Lunar Module descent engine was fired. Astronaut Armstrong used the manual control mode to land the craft, He had realized that the Sea of Tranquility was strewn with boulders, and he [29] wished to place the spacecraft down in a safe attitude. Over 500 million people beard the first words from the moon, "Contact light. Okay, engine stopped...Houston, Tranquility Base here. The Eagle has landed " Six hours after the successful landing, Astronaut Armstrong set foot on the lunar surface. Twenty minutes later, he was followed by Astronaut Aldrin (figure 11).


Figure 11. Astronaut Edwin E. Aldrin, Jr., Apollo 11 Lunar Module Pilot, stepping onto the lunar surface.

Figure 11. Astronaut Edwin E. Aldrin, Jr., Apollo 11 Lunar Module Pilot, stepping onto the lunar surface.


The astronauts quickly adapted to movement in lunar gravity, adopting a loping gait, a kind of kangaroo hop, as the most efficient for negotiating the lunar surface. They collected approximately 21 kg (46 lb) of rock and soil samples and set up the Apollo Early Surface Experiment Package (ESEP). The scientific payload consisted of a passive seismometer, a direct Earth-moon communications link, a solar wind experiment designed to isolate exotic gases in the solar wind, such as argon and krypton, for return to Earth for analysis; and an array of optical reflectors serving as targets for laser pointing systems on Earth, with the objective of more precisely measuring the distance between the Earth and the moon. After two and one-half hours of work on the lunar surface, the astronauts returned to the Lunar Module. Several hours later, the Lunar Module ascent stage was launched; it docked about three and one-half hours afterwards with the Command Module. During the return flight to Earth, the crew vacuum cleaned their clothing and equipment and took numerous precautions as part of a quarantine program to avoid carrying back to Earth any possible contamination from the moon. On Thursday, [30] July 24, after an eight-day mission, the crew splashed down in the Pacific Ocean. They donned biological isolation garments and were recovered by helicopter and transferred to the recovery ship USS Hornet where they were placed in a Mobile Quarantine Facility, a trailer modified for the purpose. They traveled in the MQF to the Lunar Receiving Laboratory in Houston, where they were kept in isolation for 21 days after lift-off from the lunar surface to preclude the possibility of contaminating the Earth with lunar organisms or material. Extensive medical and biological tests determined that no harmful organisms were present in any of the materials returned from the moon, and quarantine was terminated.

The materials returned from the 1 533 225 km (952 700 mile) journey to the moon and back were distributed to 144 scientists throughout the world. Figure 12 illustrates material from lunar rock. Among the scientific findings reported was the fact that the moon is approximately 4.6 billion years old.** The presence of minute deposits of gold , silver, and rubies in the lunar rilles was established, and evidence was found indicating that there were lava flows on the moon at one time. Additionally, three new mineral elements were discovered in the Apollo 11 samples analysis.


Figure 12. Photomicrographs of lunar rock.

Figure 12. Photomicrographs of lunar rock.


[31] During the transearth trajectory, the Apollo 11 crew reported seeing streaks, points, and flashes of light. These visual phenomena were observed with the eyes both open and dosed- It is believed that the effect was generated by extremely high energy particles of cosmic origin. These phenomena were reported by all subsequent Apollo crews.


Apollo 12

On November 14, 1969, Apollo 12 began its 244.5-hour (10-day) mission. The second lunar landing mission was crewed by Charles Conrad, Jr., Commander; Richard F. Gordon, Jr., Command Module Pilot; and Alan L. Bean, Lunar Module Pilot. During the launch, the spacecraft was struck twice by lightning, causing some interruption in electrical power. Contact with Mission Control was lost briefly. This was the first instance where any situation occurred that could have resulted in mission abort during launch. After about two hours of electrical system checkout in Earth orbit, all systems were pronounced in good working order.

The prime engineering objective of the Apollo 12 mission was to accomplish a point landing of the Lunar Module. On the Apollo 11 mission, the objective was simply to land in a safe general area, and the vehicle had touched down 6.5 km (4 miles) beyond the planned target point. The landing site selected for the Apollo 12 mission was a point 305 m (1000 ft) east and 152 m (500 ft) north of the site where Surveyor 3 had softlanded on the moon in 1967. Lunar orbit was achieved three days after launch. On November 19, Astronauts Conrad and Bean piloted the Lunar Module to the target lunar site. The Lunar Module, Intrepid, succeeded in touching down only 163 m (535 ft) from the Surveyor 3 spacecraft in the Ocean of Storms (figure 13).

Despite some loss of visibility due to dust created by the descent engine, the Apollo 12 Lunar Module landed with a reserve of propellants that was equivalent to 53 seconds of hover time. The Apollo 12 lunar surface crew made two extravehicular excursions, remaining on the moon for 31 hours, seven and three-quarters of which were spent exploring and working on the lunar surface. The first EVA was devoted to the emplacement of an Apollo Lunar Surface Experiment Package (ALSEP) (figure 14) and the collection of lunar rock samples. The ALSEP experiments included a passive seismometer to measure seismic events; a lunar atmosphere detector to determine the density of any atmosphere the moon might have had; a lunar ionosphere detector to provide information on the energy and mass spectra of the positive ions close to the lunar surface, among other objectives; and a device to measure the amount of lunar dust which accumulated on the ALSEP station.

The second lunar EVA, which lasted for three hours and 49 minutes, was devoted to collecting additional lunar samples, taking photographs, and inspecting the Surveyor 3 spacecraft. The Surveyor had made a major contribution to the Apollo 12 flight by sending back more than 6000 photographs of the Apollo 12 landing area. The Apollo 12 astronauts retrieved a television camera from the Surveyor, as well as sections of aluminum tubing and bits of glass insulation and cables. The astronauts probed the lunar surface to a depth of 81.3 cm (32 in.), bringing back rock samples from this layer of the lunar crust. In all, 34 kg (75 lb) of rock and soil samples were collected.

After ascent from the lunar surface and docking with the Command Module, the Lunar Module ascent stage was intentionally jettisoned and allowed to crash into the....



Figure 13. Surveyor 3 spacecraft (foreground) and Apollo 12 Lunar Module on the lunar surface.

Figure 13. Surveyor 3 spacecraft (foreground) and Apollo 12 Lunar Module on the lunar surface.


Figure 14. Deployment of the Apollo Lunar Surface Experiment Package (ALSEP) during the Apollo 12 mission.

Figure 14. Deployment of the Apollo Lunar Surface Experiment Package (ALSEP) during the Apollo 12 mission.


[33] ...lunar surface in order to calibrate the seismometer. The intrepid impacted the moon 64.4 km (40 miles) from the Apollo 12 landing site and the seismometer installation, setting off vibrations which continued for almost an hour. This occurrence suggested that the moon was an unstable structure and that the impact had initiated a series of "avalanches." Before leaving lunar orbit, the crew obtained extensive photographic mapping data used for training future crews.

After a safe landing in the Pacific Ocean, the Apollo 12 crew, like the Apollo 11 crew, were quarantined while medical and biological studies were performed. Again, no life forms were found in lunar materials. Another unqualified success in the space program, the Apollo 12 mission provided data through the ALSEP experiments and lunar sample collection that added greatly to man's knowledge of the moon.


Apollo 13

The harrowing odyssey of Apollo 13 ended in the South Pacific Ocean on April 17, 1970. The mission was launched from the Kennedy Space Center on April 11 with a crew comprised of James A. Lovell, Jr., Commander; John L. Swigert, Jr., Command Module Pilot (replacing Thomas K. Mattingly who was relieved of duty after exposure to Germ m measles); and Fred W. Haise, Jr., Lunar Module Pilot,

Apollo 13 would have been the first lunar mission to be dedicated almost entirely to geological research. The Lunar Module was to have landed on one of the roughest areas of the moon yet to be explored. The lunar surface crew would have traversed greater distances on the moon than any previous crews, with the distance being left to their own discretion. They were scheduled to climb one of the ridges of Fra Mauro and descend into a crater to check communications degradation, carrying a three-meter (10-ft long drill to withdraw a core sample from beneath the lunar surface.

Approximately four hours after launch, the Command Module was docked with the Lunar Module. The hatches were opened between the spacecraft and the lunar surface crew entered the Lunar Module to perform checkout operations About 56 hours into the mission, the crew reported that emergency alarms had sounded in the Command Module and that they had heard a muffled explosion. "Okay, Houston. Hey, we've got a problem here," the spacecraft transmitted. In rapid order, the spacecraft reported problems with two of the three fuel cells in the Service Module. These cells supplied electrical power for the spacecraft and produced oxygen and water as byproducts. They also reported venting of gases from the Service Module. The existence of an extreme emergency was clearly indicated.

An electrical short circuit occurring in oxygen tank number 2 caused combustion within the tank. This combustion created a pressure and temperature rise and, within seconds, rupture of the tank. This set off a pressure rise inside Service Module bay No. 4, and the panel covering the compartment blew out. Oxygen required for breathing and for the electricity-producing fuel cells was rapidly depleted. This was the most serious failure ever experienced in manned space flight, particularly since the crew was on a lunar trajectory and could not return to Earth for approximately four days.

Emergency procedures were rapidly developed by the crew and by ground control teams. The plan adopted was for the crew to man the Lunar Module, which had not been affected by the accident, and use the vehicle as a "life boat." The Lunar Module life [34] support system was used to pressurize both spacecraft. Batteries in the Lunar Module supplied power for essential communications and for operation of navigational equipment. The Lunar Module descent stage propulsion system was to be used for required maneuvers.

At first, the dearth of vital supplies was of great concern. Only about 38 hours of power, water, and oxygen were available, and this was about half as much time as would be needed to bring the craft home. However, ground-based personnel devised techniques for powering down the systems to conserve supplies. This created a hardship on the crew because the Lunar Module became uncomfortably cold, but it did provide an ample safety margin for the return trip. One significant problem was that the Lunar Module equipment could not extract sufficient amounts of carbon dioxide to make the atmosphere safe to breathe. Improvised carbon dioxide removal systems conceived by ground personnel were assembled by the crew, and these successfully resolved the problem.

On April 17, the Lunar Module was jettisoned one hour before entry into the Earth's atmosphere. The crew splashed down in the Pacific Ocean within 6 km (4 miles) of the recovery ship and were onboard the carrier within 45 minutes of touchdown. Apart from a urinary tract infection developed by one of the crewmen, the crew was in reasonably good health. Six days and 1 001933 585 km (541 000 856 nautical miles) after its launch, the hazardous journey of Apollo 13 had come to an end.***


Apollo 14

The third successful lunar expedition was commanded by America's first man in space, Alan B. Shepard, Jr., and lasted nine days. The mission's Command Module Pilot was Stuart A. Roosa, and the Lunar Module Pilot was Edgar D. Mitchell. The mission, launched on January 31, 1971, stressed geological studies and the emplacement of experimental packages. The launch was the first in the Apollo series to be delayed, this because the experience of Apollo 12 engendered caution when rain clouds were noted in the Cape Canaveral vicinity. After insertion into the translunar trajectory, approximately six attempts were required before successfully docking the Command Module with the Lunar Module.

The docked spacecraft were placed in very low lunar orbit, about 97 km (60 miles) at the high point and 15 250 m (50 000 ft) at the low point. This was the lowest lunar orbit executed in the docked configuration and another fuel saving maneuver for the lunar landing. Following separation, the Command and Service Module was inserted into a 97-km (60 mile) circular orbit. Some problems were experienced with the abort system in the Lunar Module landing radar after separation from the Command Module but the spacecraft was nonetheless brought to a safe touchdown on February 5. The first lunar EVA lasted four hours and 44 minutes, during which an ALSEP package was deployed in [35] the vicinity of Doublet Craters in the Fra Mauro region of the moon. During this EVA, the astronauts took photographs of large boulders and collected geological samples. On the next day, the lunar surface crew loaded hand tools onto a Modularized Equipment Transporter (MET) With the two-wheeled, two-legged, rickshaw type device, the astronauts set out for Cone Crater, 1.3 km (one mile) away. They were to bring the device up the crater, 122 m (400 ft) to the rim, and roll stones down its inner side. After two hours and ten minutes, 50 minutes behind schedule, the task had to be abandoned because the crew was tiring seriously and their heart rates were elevated, to 150 beats per minute in Shepard's case, and 128 in Mitchell's.

On February 6, the Lunar Module, Antares, lifted off from the moon to rendezvous with the Command Module for return to Earth. Fortunately, no further docking problems occurred. A record amount of lunar surface material, 43 kg (95 lb), was returned for study on Earth.

The Apollo 14 crew was the last to be quarantined after space flight. Their quarantine program, because of rigorous preflight procedures, was the most stringent observed. After the exposure of the Apollo 13 crewman to a communicable disease, a special program was designed to curtail the number of contacts with other individuals prior to flight. Only wives and a group of about 150 people considered essential to the mission had any direct contact with the prime and backup crews. Also, special air filtration equipment was installed in buildings they used. Three weeks from the time they took off from the lunar surface, the U.S. postlanding lunar quarantine program ended.


Apollo 15

The Apollo 15 mission was the fourth successful manned lunar landing mission, and the first m a series of three lunar missions designed to maximally utilize man's capability for scientific exploration of the lunar surface. Mission Commander, David R. Scott, a veteran of the Apollo 9 and Gemini 8 missions; Lunar Module Pilot, James B. lrwin; and Command Module Pilot/Lunar Orbital Science Experimenter, Alfred M. Worden, began their twelve-day mission on July 26, 1971. The mission included extensive lunar extravehicular activity and was the first to use the Lunar Roving Vehicle (figure 15). Changes in extravehicular life support equipment extended EVA time from four to five hours to seven to eight hours without recharging. Further, the Lunar Module was modified to permit lunar surface stays of double the length of the previous 37-hour maximum The crew accomplished detailed orbital mapping of the lunar surface from orbit using a three camera system and a laser altimeter, and placed a subsatellite in lunar orbit designed to transmit data on the moon's environment for a period of one year.

The Apollo 15 Lunar Module, Falcon, landed on the moon approximately 549 m (1800 ft) from its target, along the base of the Apennine Mountains, some of the highest on the near side of the moon, whose peaks rise to 3658 m (12 000 ft) above the plains. The landing site was selected to allow collection of lunar samples from a mare basin, mountains, and a rille in one mission

Astronaut Scott described the lunar features as very smooth. He reported that the tops of the mountains were rounded, and that there were no sharp peaks or large boulders- Scott and Astronaut lrwin made three lunar excursions, two for seven hours duration and one for six. During the first excursion, the crew deployed the Lunar Roving [36] Vehicle, set up the third lunar surface experiment package, and obtained lunar samples. A color television camera was mounted on the Lunar Rover and remotely controlled by Mission Control in Houston to permit engineers and scientists on Earth to follow the crew's activities. The crew exceeded the planned 8 km (5 mile) excursion radius and drove nearly 10.3 km (6.4 miles) on their first EVA. In all, the astronauts spent 19 1/2, hours exploring over a distance of 27.9 km (17 1/2 miles) on the moon. They collected am astounding 77.6 kg (171 lb) of lunar material.


Figure 15. Apollo 15 Lunar Roving Vehicle.

Figure 15. Apollo 15 Lunar Roving Vehicle.


The Apollo 15 crew was the first to experience any serious physiological difficulty. The crew's reactions differed radically from those of other crews, and stand out as an anomaly in the Apollo Program. Irregular heart beats were noted on the lunar surface and, again, on the return flight to Earth. Bigeminies and premature auricular and ventricular contractions were seen. In one instance, an arrhythmia recorded during a sleep period was accompanied by a very low heart rate, 28 beats per minute. These arrhythmias are believed to have been linked to potassium deficits and excessive workloads. There may also have been a relationship between preexisting, undetected coronary artery disease in one crewmember and the arrhythmias noted during the mission. The crew also recovered more slowly upon their return to Earth than did any prior or future crew.

Sixty-seven hours after their lunar landing, Astronauts Scott and Irwin fired the ascent stage engine and left the lunar surface to rendezvous with the Command Module, Endeavor. After a successful docking, the Lunar Module was jettisoned and impacted the moon at a previously determined target point to test the seismic equipment left behind.

[37] The Command Module remained in lunar orbit for two days to continue and complete scientific experiments. The subsatellite was successfully ejected from the Scientific Instrument Module Bay (SIMBAY) at this time. Spectrometric measurements were obtained of gamma ray, X-ray, and alpha particles to provide a geochemical compositional map of the moon's surface. Astronaut Worden made a "space walk" during translunar coast, spending some 90 minutes retrieving two film cassettes from the SIMBAY. The tethered EVA was the first ever made for a practical working purpose during a space mission. The crew splashed down in the Pacific Ocean on August 7.


Apollo 16

On April 16, 1972, after a delay of one month for technical problems, Apollo 16 was launched. It was the fourth mission for John W. Young, Commander. Charles M. Duke, Jr., served as Lunar Module Pilot, and Thomas K. Mattingly, ll, was the Command Module Pilot. Descartes Crater, the lunar landing site selected for Apollo 16, was chosen because it afforded the opportunity to bring back samples representing the oldest and youngest periods of the moon. Topographical features of this site indicated it to be an area of lunar volcanic and chemical evolution.

Minor problems were encountered on the outward flight which caused the crew to spend a significant amount of time troubleshooting. The first major crisis occurred after undocking of the two spacecraft on the 12th lunar orbit. With just minutes to go before starting their final descent to the lunar surface, Astronauts Young and Duke were ordered to continue orbiting and to reduce the gap between themselves and the Command Module for possible redocking because of an oscillation problem in the Service Module propulsion system. Tests showed that the system was usable and safe, but the investigation of the problem delayed the lunar landing about six hours.

The crew landed 270 m (886 ft) northwest of the planned landing site on a hilly and furrowed edge of the Kent Plateau in the Central Lunar Highlands, among the highest mountains on the lunar surface. With the aid of the Lunar Rover, Young and Duke performed three excursions. The first lasted seven hours and 11 minutes. With an improved drill, they were able to obtain three-meter (10-ft) deep core samples during this EVA without the difficulty which had exhausted the Apollo 15 crew. On the second extravehicular expedition, excellent television coverage permitted scientists on Earth to observe the nature of the landing site. To their surprise, there was no evidence of volcanic activity.

During the second EVA, the astronauts collected lunar samples at Stone Mountain and several craters. On the third excursion, the crew drove the Lunar Rover to the rim of North Ray Crater, photographing and obtaining samples. After a total of 71 hours on the moon, including 20 1/4 hours of extravehicular time, a journey of about 27 km (17 miles), and the collection of 94 kg (207 lb) of lunar samples, Young and Duke ascended from the lunar surface in the Orion. Ascent and docking went perfectly, but an incorrectly positioned switch caused the Lunar Module to tumble immediately after jettisoning. An evasive maneuver by the Command Module left the Lunar Module in lunar orbit, and it did not impact the lunar surface until much later than planned. A second particles and fields subsatellite, like that launched by Apollo 15, was successfully ejected from the SIMBAY and placed in lunar orbit.

[38] During the return to Earth, the crewmen participated m a light flash observation session and took photographs for use in a Skylab Program study on the behavior and effects of particles emanating from the spacecraft. The Command Module Pilot carried out an extravehicular activity which included the retrieval of film cassettes from the scientific instrument module cameras, inspection of the equipment, and activation of am experiment designed to provide data on microbial response to the space environment.

As a result of improved work/rest schedules and other factors, the Apollo 16 crew did not experience any of the physiological problems which characterized the Apollo 15 mission. No irregular heart beats were recorded, and the crew recovered their preflight baseline physiological status in the normal period of time postflight. On March 28, one day earlier than planned, Apollo 16 splashed down in the Pacific Ocean. The mission had lasted eleven days.


Apollo 17

On December 7, 1972, the last lunar landing mission was launched from the Kennedy Space Center. The 14-day mission was manned by Eugene A. Cernan, Commander; Ronald E. Evans, Command Module Pilot; and Dr. Harrison H. Schmitt, Lunar Module Pilot who was also a geologist. The launch, illustrated in figure 16, was the first night launch. Taurus-Littrow was Apollo 17's lunar objective. The site was chosen in the hope that samples found there would answer two key questions left unanswered by previous mission samples. The first was whether the moon had been thermally inactive for the last 3.2 billion years. Secondly, it was hoped that the Taurus-Littrow landing site would contain materials to bridge the critical gap left by previous samples, between 3.7 and 4.5 billion years.

After three hours in Earth orbit, the spacecraft were propelled by the Saturn IV-B on their path to the moon. Eighty-six hours after launch, the spacecraft went into lunar orbit. As on the four previous missions, the Saturn IV-B was maneuvered into position to impact the lunar surface after separation from the docked spacecraft. Impact occurred about 135 km (84 miles) from the planned site and was recorded by the passive seismometers deployed by Apollo 12, 14, 15, and 16. After 21 1/2 hours in lunar orbit, the Lunar Module was undocked, and about three and one-half hours after that, Astronauts Cernan and Schmitt set their craft down on the southeastern rim of the Sea of Serenity at the Taurus-Littrow site.

The crew remained on the lunar surface for about 75 hours, and made three explorations, totaling 22 hours. Again, with the help of the Lunar Rover, large areas of the moon were traversed At the end of the mission, the astronauts had covered 34 km (21 miles) of lunar surface. The crew's first task was to deploy the Lunar Surface Experiment Package. This time, the ALSEP contained a heat flow experiment to replace a comparable experiment which had suffered a failure on Apollo 16. The objective was to measure heat flow from the interior of the moon to the surface to provide an understanding of the moon's core temperature and, perhaps, the processes involved in its formation and activity. Other experiments in the package included a lunar surface gravity experiment, am atmosphere composition experiment, instruments to detect micrometeorites, and seismic profile equipment for the measurement of moonquake activity, magnetic fields, solar wind, and other parameters.



Figure 16. Night launch of Apollo 17.

Figure 16. Night launch of Apollo 17.


The scientific yield of Apollo 17 was perhaps the richest of any Apollo lunar landing mission. The crew collected samples of a greater variety than any previously collected. They discovered significant materials indicating lunar volcanic activity. On their second EVA, the astronauts discovered a unique, orange colored surface material never before observed on the moon. Postflight analysis indicated this material contained magnetite. The site had a very large landslide that was also sampled by the crew. By the end of their 75-hour stay, the crew had collected 110 kg (243 lb) of lunar materials. This was a record in the lunar exploration program.

On previous missions, the Command Module Pilot had taken photographs of the moon with the panoramic and mapping cameras and had utilized the laser altimeter while in lunar orbit during the period of lunar surface exploration. Three new experiments were included in the Service Module of Apollo 17 and were the responsibility of the Command Module Pilot. He conducted lunar atmospheric composition and density measurements with an ultraviolet spectrometer, used an infrared radiometer to map lunar thermal characteristics, and a lunar sounder for the acquisition of subsurface structural data.

The Lunar Module successfully mated with the Command Module and, as had been done on previous missions, the former was jettisoned as part of the seismic experiment after transfer of the crew. The Command Module remained in lunar orbit for two days to complete the experiments begun by the Command Module Pilot. On December 20, the Command Module, Endeavor, landed in the Pacific Ocean west of Hawaii. With this event, the Apollo Program wag brought to a conclusion.


[40] Concluding Remarks


The Apollo Lunar Landing Program spanned a seven-year period and included seventeen missions. The 29 astronauts who flew in the Program spent a total of 7506 hours in flight. Twelve of them were placed on the moon for a total of more than four man-weeks and all were returned safely to Earth. The Apollo Program is viewed as one of the greatest scientific and engineering successes of man, a national event which held the attention of millions of people in this country and the world, and required the development of new and complex equipment ranging from the spacecraft itself to the tools and clothing used by the crewmen. The Program made it possible to gather lunar material that has begun to disclose clues about the origin of our solar system. And, at last, we were certain that no life exists on the moon. The Apollo Program established that the psychological and physiological effects of the space environment on man were not at all as severe as had been predicted by some scientists. But, perhaps the greatest significance of the Apollo Program lies in the fact that it provided information which will assist scientists and engineers in developing the biomedical and technical support necessary for man to venture still further into the solar system.

* In commemoration of the crew, the mission was redesignated Apollo 1.

** For further information concerning lunar scientific discovering, the reader is referred to the Apollo 11 Lunar Science, Conference, Volumes 1-3 (Pergamon Press, 1970); the Proceedings of the Second Lunar Science Conference, Volumes 1.3 (The MIT Press, 1971); and the Proceedings of the Third Through Fifth Lunar Science Conferences (Pergamon Press, 1972-l974).

***Anon The Apollo 13 Accident. Hearings before the Committee on Science and Astronautics, U.S. House of Representatives. U.S. Government Printing Office (Washington, D. C.), June 16, 1970.

Anon: The Apollo 13 Mission Review. Hearings before the Committee on Aeronautical and Space Sciences, U.S. Senate, 91st Congress, 2nd Session. U.S. Government Printing Office, (Washington, D. C.), June 30, 1970.