sábado, 12 de enero de 2013

It was the cold war and the USA had to prove its superiority in space at all costs.
Did we go to the moon in 1969?

We might have done, but the pictures the astronauts took are full of inconsistencies. NASA did not want to expose the astronauts to the dangers of the missions, like going through the Van Allen radiation belts and the fact that they had never sent anyone beyond earth orbit.

The USA had to defeat Russia’s superiority in the space race, even if they had to fake the journey to the moon and back in front of the whole world.

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Apollo program

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Astronaut Buzz Aldrin stands on the Moon

Apollo 11 crew member Buzz Aldrin, second person to walk on the Moon, July 1969

The Apollo program was the third human spaceflight program carried out by the National Aeronautics and Space Administration (NASA), the United States' civilian space agency. First conceived during the Presidency of Dwight D. Eisenhower as a three-man spacecraft to follow the one-man Project Mercury which put the first Americans in space, Apollo was later dedicated to President John F. Kennedy's national goal of "landing a man on the Moon and returning him safely to the Earth" by the end of the 1960s, which he proposed in a May 25, 1961 address to Congress. Project Mercury was followed by the two-man Project Gemini (1962–66). The first manned flight of Apollo was in 1968 and it succeeded in landing the first humans on Earth's Moon in 1969 through 1972.

Kennedy's goal was accomplished on the Apollo 11 mission when astronauts Neil Armstrong and Buzz Aldrin landed their Lunar Module (LM) on the Moon on July 20, 1969 and walked on its surface while Michael Collins remained in lunar orbit in the command spacecraft, and all three landed safely on Earth on July 24. Five subsequent Apollo missions also landed astronauts on the Moon, the last in December 1972. In these six spaceflights, 12 men walked on the Moon.

Apollo ran from 1961 to 1972, and was supported by the two-man Gemini program which ran concurrently with it from 1962 to 1966. Gemini missions developed some of the space travel techniques that were necessary for the success of the Apollo missions. Apollo used Saturn family rockets as launch vehicles. Apollo / Saturn vehicles were also used for an Apollo Applications program which consisted of three Skylab space station missions in 1973–74.

Apollo succeeded despite the major setback of a 1967 Apollo 1 cabin fire that killed the entire crew during a pre-launch test. Six manned landings on the Moon were achieved. A seventh landing mission, the 1970 Apollo 13 flight, failed in transit to the Moon when an oxygen tank explosion disabled the command spacecraft's propulsion and life support, forcing the crew to use the Lunar Module as a "lifeboat" for these functions to return to Earth safely.

Apollo set several major human spaceflight milestones. It stands alone in sending manned missions beyond low Earth orbit; Apollo 8 was the first manned spacecraft to orbit another celestial body, while the final Apollo 17 mission marked the sixth Moon landing and the ninth manned mission beyond low Earth orbit. The program returned 842 pounds (382 kg) of lunar rocks and soil to Earth, greatly contributing to the understanding of lunar geology. The program laid the foundation for NASA's current human spaceflight capability, and funded construction of its Johnson Space Center and Kennedy Space Center. Apollo also spurred advances in many areas of technology incidental to rocketry and manned spaceflight, including avionics, telecommunications, and computers.

Background

NASA expansion

At the time of Kennedy's proposal, only one American had flown in space—less than a month earlier—and NASA had not yet sent an astronaut into orbit. Even some NASA employees doubted whether Kennedy's ambitious goal could be met.^[12] Kennedy even came close to agreeing to a joint US-USSR Moon mission, to eliminate duplication of effort.^[13]

Landing men on the Moon by the end of 1969 required the most sudden burst of technological creativity, and the largest commitment of resources ($24 billion), ever made by any nation in peacetime. At its peak, the Apollo program employed 400,000 people and required the support of over 20,000 industrial firms and universities.^[14]

Manned Spacecraft Center

Main article: Lyndon B. Johnson Space Center

It became clear that managing the Apollo program would exceed the capabilities of Robert Gilruth's Space Task Group, which had been directing the nation's manned space program from NASA's Langley Research Center. So Gilruth was given authority to grow his organization into a new NASA center, the Manned Spacecraft Center (MSC). A site was chosen in Houston, Texas on land donated by Rice University, and Administrator Webb announced the conversion on September 19, 1961.^[15] It was also clear NASA would soon outgrow its practice of controlling missions from its Cape Canaveral Air Force Station launch facilities in Florida, so a new Mission Control Center would be included in the MSC.

President Kennedy speaks at Rice University (17 min, 47 sec)

In September 1962, by which time two Project Mercury astronauts had orbited the Earth, Gilruth had moved his organization to rented space in Houston, and construction of the MSC facility was under way, Kennedy visited Rice to reiterate his challenge in a famous speech:

"But why, some say, the Moon? Why choose this as our goal? And they may well ask, why climb the highest mountain? Why, 35 years ago, fly the Atlantic? ...
We choose to go to the Moon. We choose to go to the Moon in this decade and do the other things, not because they are easy, but because they are hard; because that goal will serve to organize and measure the best of our energies and skills; because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one we intend to win ... ."

—^[16]

The MSC was completed in September 1963. It was renamed in honor of Lyndon Johnson by federal law, soon after his death in 1973.^[17]

Launch Operations Center

Main article: Kennedy Space Center

It also became clear that Apollo would outgrow the Canaveral launch facilities in Florida. The two newest launch complexes were already being built for the Saturn I and IB rockets at the northernmost end: LC-34 and LC-37. But an even bigger facility would be needed for the mammoth rocket required for the manned lunar mission, so land acquisition was started in July 1961 for a Launch Operations Center (LOC) immediately north of Canaveral at Merritt Island. The design, development and construction of the center was conducted by Kurt H. Debus, a member of Dr. Wernher von Braun's original V-2 rocket engineering team. Debus was named the LOC's first Director.^[18] Construction began in November 1962. Upon Kennedy's death, President Johnson issued an executive order on November 29, 1963 to rename the LOC and Cape Canaveral in honor of Kennedy.^[19]

The LOC included Launch Complex 39, a Launch Control Center, and a 130 million cubic foot (3.7 million cubic meter) Vehicle Assembly Building in which the space vehicle (launch vehicle and spacecraft) would be assembled on a Mobile Launcher Platform and then moved by a transporter to one of several launch pads. Although at least three pads were planned, only two, designated A and B, were completed in October 1965. The LOC also included an Operations and Checkout Building (OCB), to which Gemini and Apollo spacecraft were initially received prior to being mated to their launch vehicles. The Apollo spacecraft could be tested in two vacuum chambers capable of simulating atmospheric pressure at altitudes up to 250,000 feet (76 km), which is nearly a vacuum.^[20]^[21]

Organization

Administrator Webb realized that in order to keep Apollo costs under control, he had to develop greater project management skills in his organization, so he recruited Dr. George E. Mueller for a high management job. Mueller accepted, on the condition that he have a say in NASA reorganization necessary to effectively administer Apollo. Webb then worked with Associate Administrator (later Deputy Administrator) Robert Seamans to reorganize the Office of Manned Space Flight (OMSF).^[22] On July 23, 1963, Webb announced Mueller's appointment as Deputy Associate Administrator for Manned Space Flight, to replace then Associate Administrator D. Brainard Holmes on his retirement effective September 1. Under Webb's reorganization, the directors of the Manned Spacecraft Center (Gilruth), Marshall Space Flight Center (von Braun), and the Launch Operations Center (Debus) effectively reported to Mueller.^[23]

Based on his industry experience on Air Force missile projects, Mueller realized some skilled managers could be found among high-ranking officers in the US Air Force, so he got Webb's permission to recruit General Samuel C. Phillips, who gained a reputation for his effective management of the Minuteman program, as OMSF program controller. Phillips' superior officer Bernard Schriever agreed to loan Phillips to NASA, along with a staff of officers under him, on the condition that Phillips be made Apollo Program Director. Mueller agreed, and Phillips managed Apollo from January 1964, until it achieved the first manned landing in July 1969, after which he returned to Air Force duty.^[24]

Choosing a mission mode

John Houbolt explaining the LOR concept

Once Kennedy had defined a goal, the Apollo mission planners were faced with the challenge of designing a set of flights that could meet it while minimizing risk to human life, cost, and demands on technology and astronaut skill. Four possible mission modes were considered:

Direct Ascent: A spacecraft would travel directly to the Moon as a unit, land, and return leaving its landing stage on the Moon. This plan would have required a more powerful launch vehicle, the planned Nova rocket.
Earth Orbit Rendezvous (EOR): Multiple rockets (up to 15 in some plans) would be launched, carrying various parts of a Direct Ascent spacecraft and propulsion units for translunar injection. These would be assembled into a single spacecraft in Earth orbit.
Lunar Orbit Rendezvous (LOR): One Saturn V would launch a spacecraft that was composed of modular parts. A command module would remain in orbit around the Moon, while a lunar excursion module would descend to the Moon, return to dock with the command ship, and then be discarded. In contrast with the other plans, LOR required only a small part of the spacecraft to land on the Moon, thereby minimizing the mass to be launched from the Moon's surface for the return trip.
Lunar Surface Rendezvous: Two spacecraft would be launched in succession. The first, an automated vehicle carrying propellant for the return to Earth, would land on the Moon, to be followed some time later by the manned vehicle. Propellant would have to be transferred from the automated vehicle to the manned vehicle.

Spacecraft

Main article: Apollo spacecraft

Preliminary design studies of Apollo spacecraft began in 1960 as a three-man command module supported by one of several service modules providing propulsion and electrical power, sized for use in various possible missions, such as: shuttle service to a space station, circumlunar flight, or return to Earth from a lunar landing. Once the Moon landing goal became official, detailed design began of the Command/Service Module (CSM), in which the crew would spend the entire direct-ascent mission and lift off from the lunar surface for the return trip. The final choice of lunar orbit rendezvous changed the CSM's role to a translunar ferry used to transport the crew and a new spacecraft, the Lunar Excursion Module (LEM, later shortened to Lunar Module, LM), which would take two men to the lunar surface and return them to the CSM.^[30]

Command/Service Module

Main article: Apollo Command/Service Module

The cone-shaped Command Module, attached to the cylindrical Service Module, orbits the Moon with a panel removed, exposing the Scientific Instrument Module

Apollo 15 CSM in lunar orbit

The Command Module (CM) was the conical crew cabin, designed to carry three astronauts from launch to lunar orbit and back to an Earth ocean landing. It was the only component of the Apollo spacecraft to survive without major configuration changes as the program evolved from the early Apollo study designs. Its exterior was covered with an ablative heat shield, and had its own reaction control system (RCS) engines to control its attitude and steer its atmospheric entry path. Parachutes were carried to slow its descent to splashdown. The module was 11.42 feet (3.48 m) tall, 12.83 feet (3.91 m) in diameter, and weighed approximately 12,250 pounds (5,560 kg).^[31]

A cylindrical Service Module (SM) supported the Command Module, with a service propulsion engine and an RCS with propellants, and a fuel cell power generation system with liquid hydrogen and liquid oxygen reactants. A high-gain S-band antenna was used for long-distance communications on the lunar flights. On the extended lunar missions, an orbital scientific instrument package was carried. The Service Module was discarded just before re-entry. The module was 24.6 feet (7.5 m) long and 12.83 feet (3.91 m) in diameter. The initial lunar flight version weighed approximately 51,300 pounds (23,300 kg) fully fueled, while a later version designed to carry a lunar orbit scientific instrument package weighed just over 54,000 pounds (24,000 kg).^[31]

North American Aviation won the contract to build the CSM, and also the second stage of the Saturn V launch vehicle for NASA. Because the CSM design was started early before the selection of lunar orbit rendezvous, the service propulsion engine was sized to lift the CSM off of the Moon, and thus was oversized to about twice the thrust required for translunar flight.^[32] Also, there was no provision for docking with the Lunar Module. A 1964 program definition study concluded that the initial design should be continued as Block I which would be used for early testing, while Block II, the actual lunar spacecraft, would incorporate the docking equipment and take advantage of the lessons learned in Block I development.^[30]

Lunar Module

Main article: Apollo Lunar Module

Apollo 16 LM on the Moon

The Lunar Module (LM) was designed to descend from lunar orbit to land two astronauts on the Moon and take them back to orbit to rendezvous with the Command Module. Not designed to fly through the Earth's atmosphere or return to Earth, its fuselage was designed totally without aerodynamic considerations, and was of an extremely lightweight construction. It consisted of separate descent and ascent stages, each with its own engine. The descent stage contained storage for the descent propellant, surface stay consumables, and surface exploration equipment. The ascent stage contained the crew cabin, ascent propellant, and a reaction control system. The initial LM model weighed approximately 33,300 pounds (15,100 kg), and allowed surface stays up to around 34 hours. An Extended Lunar Module weighed over 36,200 pounds (16,400 kg), and allowed surface stays of over 3 days.^[31]

The contract for design and construction of the Lunar Module was awarded to Grumman Aircraft Engineering Corporation, and the project was overseen by Tom Kelly.^[33]

Launch vehicles

Four Apollo rocket assemblies, drawn to scale: Little Joe II, Saturn I, Saturn IB, and Saturn V.

Before the Apollo program began, Wernher von Braun and his team of rocket engineers had started work on plans for very large launch vehicles, the Saturn series, and the even larger Nova series. In the midst of these plans, von Braun was transferred from the Army to NASA, and made Director of the Marshall Space Flight Center (MSFC). The initial direct ascent plan to send the three-man Apollo Command/Service Module directly to the lunar surface, on top of a large descent rocket stage, would require a Nova-class launcher, with a lunar payload capability of over 180,000 pounds (82,000 kg).^[34] However, the June 11, 1962 decision to use lunar orbit rendezvous enabled the Saturn V to replace the Nova, and the MSFC proceeded to develop the Saturn rocket family for Apollo.^[35]

Little Joe II

Main article: Little Joe II

Since Apollo, like Mercury, would require a launch escape system (LES) in case of a launch failure, a relatively small rocket was required for qualification testing of this system. However, a size bigger than the NAA Little Joe would be required, so the Little Joe II was built by General Dynamics/Convair. After an August, 1963 qualification test flight,^[36] four LES test flights (A-001 through 004) were made at the White Sands Missile Range between May 1964 and January 1966.^[37]

Saturn I

Main article: Saturn I

Saturn I, the first US heavy lift launch vehicle, was initially planned to launch partially equipped CSM's in low Earth orbit tests. The S-I first stage burned RP-1 with liquid oxygen (LOX) oxidizer, to produce 1,500,000 pounds-force (6,670 kN) of thrust. The S-IV second stage used six liquid hydrogen-fueled RL-10 engines with 90,000 pounds-force (400 kN) of thrust. A planned Centaur (S-V) third stage with two RL-10 engines, never flew on Saturn I.^[38]

The first four Saturn I test flights were launched from LC-34, with only live first stages, carrying dummy upper stages filled with water. The first flight with a live S-IV was launched from LC-37. This was followed by five launches of boilerplate CSMs into orbit in 1964 and 1965. The last three of these further supported the Apollo program by also carrying Pegasus satellites, which verified the safety of the translunar environment by measuring the frequency and severity of micrometeorite impacts.^[39]

A Saturn IB rocket launches Apollo 7, 1968.

In September 1962, NASA planned to launch four manned CSM flights on the Saturn I from the fall of 1965 through 1966, concurrent with Project Gemini. However, the 22,500-pound (10,200 kg) payload capacity^[40] would have severely limited the systems which could be included, so the decision was made in October 1963 to use the uprated Saturn IB for all manned Earth orbital flights.^[41]

Saturn IB

Main article: Saturn IB

The Saturn IB was an upgraded version of the Saturn I. The S-IB first stage increased the thrust to 1,600,000 pounds-force (7,120 kN), and the second stage replaced the S-IV with the S-IVB-200, powered by a single J-2 engine burning liquid hydrogen fuel with LOX, to produce 200,000 lbf (890 kN) of thrust. A restartable version of the S-IVB was used as the third stage of the Saturn V. The Saturn IB could send over 40,000 pounds (18,100 kg) into low Earth orbit, sufficient for a partially fueled CSM or the LM.^[42] Saturn IB launch vehicles and flights were designated with an AS-200 series number, "AS" indicating "Apollo Saturn" and the "2" indicating the second member of the Saturn rocket family.

Saturn V

A Saturn V rocket launches Apollo 11 in 1969

Main article: Saturn V

The three-stage Saturn V was designed to send a fully fueled CSM and LM to the Moon. It was 33 feet (10.1 m) in diameter and stood 363 feet (110.6 m) tall with its 96,800-pound (43,900 kg) lunar payload. Its capability grew to 103,600 pounds (47,000 kg) for the later advanced lunar landings. The S-IC first stage burned RP-1/LOX for a rated thrust of 7,500,000 pounds-force (33,400 kN), which was upgraded to 7,610,000 pounds-force (33,900 kN). The second and third stages burned liquid hydrogen, and the third stage was a modified version of the S-IVB, with thrust increased to 230,000 lbf (1,020 kN) and capability to restart the engine for translunar injection after reaching a parking orbit.^[43]

Saturn V launch vehicles and flights were designated with an AS-500 series number, "AS" indicating "Apollo Saturn" and the "5" indicating Saturn V. Since Apollo, like Project Mercury, used more than one launch vehicle for space missions, NASA similarly used the spacecraft-launch vehicle combination series numbers AS-10x for Saturn I, AS-20x for Saturn IB, and AS-50x for Saturn V (c/w Mercury-Redstone 3, Mercury-Atlas 6), to designate and plan all missions, rather than numbering them sequentially as in Project Gemini. However, this would be changed by the time manned flights began.^[44]

Astronauts

Main article: List of Apollo astronauts

Apollo 1 crew: Edward H. White, command pilot Gus Grissom, and Roger Chaffee

NASA's Director of Flight Crew Operations during the Apollo program was Donald K. "Deke" Slayton, one of the original Mercury Seven astronauts who was medically grounded in September 1962 due to a heart murmur. Slayton was responsible for making all Gemini and Apollo crew assignments.^[45]

Apollo 11 crew, who made the first manned landing: commander Neil Armstrong, CM pilot Michael Collins, and LM pilot Buzz Aldrin

Thirty-two astronauts were assigned to fly missions in the Apollo program. Twenty-four of these left Earth’s orbit and flew around the Moon between December 1968 and December 1972 (three of them twice). Half of the 24 walked on its surface, though none of them returned to the Moon after landing once. One of the Moon-walkers was a trained geologist. Of the 32, Gus Grissom, Edward H. White, and Roger Chaffee were killed during a ground test in preparation for their Apollo 1 mission.^[46]

The Apollo astronauts were chosen from the Project Mercury and Gemini veterans, plus from two later astronaut groups. All missions were commanded by Gemini or Mercury veterans. Crews on all development flights (except the Earth orbit CSM development flights), through the first two landings on Apollo 11 and Apollo 12, included at least two (sometimes three) Gemini veterans. Dr. Harrison Schmitt, a geologist, was the first NASA scientist astronaut to fly in space, and landed on the Moon on the last mission, Apollo 17. Schmitt participated in the lunar geology training of all of the Apollo landing crews.^[47]

Lunar mission profile

The nominal planned lunar landing mission proceeded as follows:

Launch The 3 Saturn V stages burn for about 11 minutes to achieve a 100-nautical-mile (190 km) circular parking orbit. The third stage burns a small portion of its fuel to achieve orbit.
Translunar injection After one to two orbits to verify readiness of spacecraft systems, the S-IVB third stage reignites for about 6 minutes to send the spacecraft to the Moon.
Transposition and docking (1) The SLA panels separate to free the CSM and expose the LM. The CMP moves the CSM out a safe distance, and turns 180°.
Transposition and docking (2), The CMP docks with the LM, and pulls the combined spacecraft away from the S-IVB, which then is sent into solar orbit. The lunar voyage takes between 2 and 3 days. Midcourse corrections are made as necessary using the SM engine.
Lunar orbit insertion The spacecraft passes about 60 nautical miles (110 km) behind the Moon, and the SM engine is fired to slow the spacecraft and put it into a 60-by-170-nautical-mile (110 by 310 km) orbit, which is soon circularized at 60 nautical miles by a second burn.
After a rest period, the CDR and LMP move to the LM, power up its systems, and deploy the landing gear. The CSM and LM separate; the CMP visually inspects the LM, then the LM crew move a safe distance away and fire the descent engine for Descent orbit insertion, which takes it to a perilune of about 50,000 feet (15 km).
Powered descent At perilune, the descent engine fires again to start the descent. The CDR takes over manual control after pitchover for a vertical landing.
The CDR and LMP perform one or more EVAs exploring the lunar surface and collecting samples, alternating with rest periods.
The ascent stage lifts off, using the descent stage as a launching pad.
The LM rendezvouses and docks with the CSM.
The CDR and LMP transfer back to the CM with their material samples, then the LM ascent stage is jettisoned, to eventually fall out of orbit and crash on the surface.
Trans-Earth injection The SM engine fires to send the CSM back to Earth.
The SM is jettisoned just before reentry, and the CM turns 180° to face its blunt end forward for reentry.
Atmospheric drag slows the CM, surrounding it with an envelope of ionized air which causes a communications blackout for several minutes.
Parachutes are deployed, slowing the CM for a splashdown in the Pacific Ocean. The astronauts are recovered and brought to an aircraft carrier.

Lunar flight profile.

Profile variations

After Apollo 12 placed the second of several seismometers on the Moon, the S-IVBs on subsequent missions were deliberately crashed on the Moon instead of being sent to solar orbit, as an active seismic experiment to induce vibrations in the Moon.
The first three lunar missions (Apollo 8, Apollo 10, and Apollo 11) used a free return trajectory, keeping a flight path coplanar with the lunar orbit, which would allow a return to Earth in case the SM engine failed to make lunar orbit insertion. Landing site lighting conditions on later missions dictated a lunar orbital plane change, which required a course change maneuver soon after TLI, and eliminated the free-return option.
On later landing flights, the SM engine was used instead of the LM engine to begin powered descent, in order to allow a greater fuel reserve for landing.
On Apollo 12 and later missions, the jettisoned LM ascent stages were deliberately crashed on the Moon at known locations, as another active seismic experiment. The only exceptions to this were the Apollo 13 LM which burned up in the Earth's atmosphere, and Apollo 16, where a loss of attitude control after jettison prevented making a targeted impact.^[48]

Development history

Unmanned flight tests

Composite image of unmanned development Apollo mission launches in chronological sequence.

Apollo unmanned development mission launches. Click on a launch image to read the main article about each mission.

Preparation for manned flight

Two manned orbital Block I CSM missions were planned: AS-204 and AS-205. The Block I crew positions were titled Command Pilot, Senior Pilot, and Pilot. The Senior Pilot would assume navigation duties, while the Pilot would function as a systems engineer. The astronauts would wear a modified version of the Gemini spacesuit.

After an unmanned LM test flight AS-206, a crew would fly the first Block II CSM and LM in a dual mission known as AS-207/208, or AS-278 (each spacecraft would be launched on a separate Saturn IB.) The Block II crew positions were titled Commander (CDR), Command Module Pilot (CMP), and Lunar Module Pilot (LMP). The astronauts would begin wearing a new Apollo spacesuit, designed to accommodate lunar extravehicular activity. The traditional visor helmet was replaced with a clear "fishbowl" type for greater visibility, and the lunar surface EVA suit would include a water-cooled undergarment.

Grissom, White and Chaffee were named for the AS-204 crew on March 21, 1966, with a backup crew consisting of Gemini veterans James McDivitt and David Scott, with rookie Russell L. "Rusty" Schweickart. Mercury/Gemini veteran Wally Schirra and rookies Donn Eisele and Walter Cunningham were named as the prime crew for AS-205.

In December 1966, the AS-205 mission was canceled, since the validation of the CSM would be accomplished on the 14-day first flight, and AS-205 would have been devoted to space experiments and contribute no new engineering knowledge about the spacecraft. Its Saturn IB was allocated to the dual mission, now redesignated AS-205/208 or AS-258, planned for August 1967. McDivitt, Scott and Schweickart were promoted to the prime AS-258 crew, and Schirra, Eisele and Cunningham were reassigned as the Apollo 1 backup crew.^[52]

Program delays

The spacecraft for the AS-202 and AS-204 missions were delivered by North American Aviation to KSC with long lists of equipment problems which had to be corrected before flight; these delays caused the launch of AS-202 to slip behind AS-203, and eliminated hopes the first manned mission might be ready to launch as soon as November 1966, concurrently with the last Gemini mission. Eventually the planned AS-204 flight date was pushed to February 21, 1967.^[53]

North American Aviation was prime contractor not only for the Apollo CSM, but for the Saturn V S-II second stage as well, and delays in this stage pushed the first unmanned Saturn V flight AS-501 from late 1966 to November 1967. (The initial assembly of AS-501 had to use a dummy spacer spool in place of the stage.)^[54]

The problems with North American were severe enough in late 1965 to cause Manned Space Flight Administrator George Mueller to appoint program director Samuel Phillips to head a "tiger team" to investigate North American's problems and identify corrections. Phillips documented his findings in a December 19 letter to NAA president Lee Atwood, with a strongly worded letter by Mueller, and also gave a presentation of the results to Mueller and Deputy Administrator Robert Seamans.^[55]

Meanwhile, Grumman was also encountering problems with the Lunar Module, eliminating hopes it would be ready for manned flight in 1967, not long after the first manned CSM flights.^[56]

Disaster strikes

Main article: Apollo 1

Grissom, White, and Chaffee decided to name their flight Apollo 1 as a motivational focus on the first manned flight. They trained and conducted tests of their spacecraft at North American, and in the altitude chamber at the Kennedy Space Center. A "plugs-out" test was planned for January, which would simulate a launch countdown on pad 34 with the spacecraft transferring from pad-supplied to internal power. If successful, this would be followed by a more rigorous countdown simulation test closer to the February 21 launch, with both spacecraft and launch vehicle fueled.^[57]

Charred remains of the Apollo 1 cabin interior

The plugs-out test began on the morning of January 27, 1967, and immediately was plagued with problems. First the crew noticed a strange odor in their spacesuits, which delayed the sealing of the hatch. Then, communications problems frustrated the astronauts and forced a hold in the simulated countdown. During this hold, an electrical fire began in the cabin, and spread quickly in the high pressure, 100% oxygen atmosphere. Pressure rose high enough from the fire that the cabin burst and the fire erupted onto the pad area, frustrating attempts to rescue the crew. The astronauts were asphyxiated, before the hatch could be opened.^[58]

NASA immediately convened an accident review board, overseen by both houses of Congress. While the determination of responsibility for the accident was complex, the review board concluded that "deficiencies existed in Command Module design, workmanship and quality control."^[59] At the insistence of NASA Administrator Webb, North American removed Harrison Storms as Command Module program manager.^[60] Webb also reassigned Apollo Spacecraft Program Office (ASPO) Manager Joseph Francis Shea, replacing him with George Low.^[61]

To remedy the causes of the fire, changes were made in the Block II spacecraft and operational procedures, the most important of which were use of a nitrogen/oxygen mixture instead of pure oxygen before and during launch, and removal of flammable cabin and space suit materials. The Block II design already called for replacement of the Block I plug-type hatch cover with a quick-release, outward opening door. NASA discontinued the manned Block I program, using the Block I spacecraft only for unmanned Saturn V flights. Crew members would also exclusively wear the Block II space suits and be designated by the Block II titles, regardless of whether or not a LM was present on the flight.

Unmanned Saturn V and LM tests

On April 24, 1967, Mueller published an official Apollo mission numbering scheme, using sequential numbers for all flights, manned or unmanned. The sequence would start with Apollo 4 to cover the first three unmanned flights while retiring the Apollo 1 designation to honor the crew per their widows' wishes.^[44]

In September 1967, Mueller approved a sequence of mission types which had to be successfully accomplished in order to achieve the manned lunar landing. Each step had to be successfully accomplished before the next ones could be performed, and it was unknown how many tries of each mission would be necessary; therefore letters were used instead of numbers. The A missions were unmanned Saturn V validation; B was unmanned LM validation using the Saturn IB; C was manned CSM Earth orbit validation using the Saturn IB; D was the first manned CSM/LM flight (this replaced AS-258, using a single Saturn V launch); E would be a higher Earth orbit CSM/LM flight; F would be the first lunar mission, testing the LM in lunar orbit but without landing (a "dress rehearsal"); and G would be the first manned landing. The list of types covered follow-on lunar exploration to include H lunar landings, I for lunar orbital survey missions, and J for extended-stay lunar landings.^[62]

The delay in the CSM caused by the fire enabled NASA to catch up on man-rating the LM and Saturn V. Apollo 4 (AS-501) was the first unmanned flight of the Saturn V, carrying a Block I CSM on November 9, 1967. The capability of the Command Module's heat shield to survive a trans-lunar reentry was demonstrated by using the Service Module engine to ram it into the atmosphere at higher than the usual Earth-orbital reentry speed. This was followed on April 4, 1968 by Apollo 6 (AS-502), which carried a CSM and a LM Test Article as ballast. The intent of this mission was to achieve trans-lunar injection, followed closely by a simulated direct-return abort, using the Service Module engine to achieve another high-speed reentry. However, the Saturn V experienced pogo oscillation, a problem caused by non-steady engine combustion, which damaged fuel lines in the second and third stages. Two S-II engines shut down prematurely, but the remaining engines were able to compensate. However, the damage to the third stage engine was more severe, preventing it from restarting for trans-lunar injection. Mission controllers were able to use the Service Module engine to essentially repeat the flight profile of Apollo 4. Based on the good performance of Apollo 6 and identification of satisfactory fixes to the Apollo 6 problems, NASA declared the Saturn V ready to fly men, cancelling a third unmanned test.^[63]

Apollo 5 (AS-204) was the first unmanned test flight of LM in Earth orbit, launched from pad 37 on January 22, 1968, by the Saturn IB that would have been used for Apollo 1. The LM engines were successfully test-fired and restarted, despite a computer programming error which cut short the first descent stage firing. The ascent engine was fired in abort mode, known as a "fire-in-the-hole" test, where it was lit simultaneously with jettison of the descent stage. Although Grumman wanted a second unmanned test, George Low decided the next LM flight would be manned.^[64]

Manned development missions

Composite image of 6 manned Apollo development mission patches, from Apollo 1 to Apollo 11.

Apollo manned development mission patches. Click on a patch to read the main article about that mission.

Apollo 7, launched from pad 34 on October 11, 1968, was the C mission, crewed by Schirra, Eisele and Cunningham. It was an 11-day Earth-orbital flight which tested the CSM systems.

Apollo 8 was planned to be the D mission in December 1968, crewed by McDivitt, Scott and Schweickart, launched on a Saturn V instead of two Saturn IB's. However, in the summer it had become clear that the LM would not be ready in time. Rather than waste the Saturn V on another simple Earth-orbiting mission, ASPO Manager George Low suggested the bold step of sending Apollo 8 to the Moon instead, deferring the D mission to the next mission in March 1969, and eliminating the E mission. This would keep the program on track. The decision was not announced publicly until successful completion of Apollo 7. Gemini veterans Frank Borman and James Lovell, and rookie William Anders captured the world's attention by making 10 lunar orbits in 20 hours and transmitting television pictures of the lunar surface on Christmas Eve, and returning safely to Earth.

For more details on this topic, see Apollo 8.

The following March, LM flight, rendezvous and docking were successfully demonstrated in Earth orbit on Apollo 9, and Schweickart tested the full lunar EVA suit with its Portable Life Support System outside the LM.

The F mission was successfully carried out on Apollo 10 in May 1969 by Gemini veterans Thomas Stafford, John Young and Eugene Cernan. Stafford and Cernan took the LM to within 50,000 feet (15 km) of the lunar surface.

The G mission was achieved on Apollo 11 in July 1969 by an all-Gemini veteran crew consisting of Neil Armstrong, Michael Collins and Buzz Aldrin. Armstrong and Aldrin performed the first landing at the Sea of Tranquility at 20:17:40 UTC on July 20, 1969. They spent a total of 21 hours, 36 minutes on the surface, and spent 2 hours, 36 minutes outside the spacecraft, walking on the surface, taking photographs, collecting material samples, and deploying automated scientific instruments, while continuously sending black-and-white television back to Earth. The astronauts returned safely on July 24.

That's one small step for [a] man, one giant leap for mankind.

—Neil Armstrong, just after stepping onto the Moon's surface^[65]

For more details on this topic, see Apollo 11 and Neil Armstrong#First Moon walk.

Lunar landings

Composite image of 6 production manned Apollo lunar landing mission patches, from Apollo 12 to Apollo 17.

Apollo production manned lunar landing mission patches. Click on a patch to read the main article about that mission.

Apollo landings on the Moon, 1969–1972

In November 1969, Gemini veteran Charles "Pete" Conrad and rookie Alan L. Bean made a precision landing on Apollo 12 within walking distance of the Surveyor 3 unmanned lunar probe, which had landed in April 1967 on the Ocean of Storms. The Command Module Pilot was Gemini veteran Richard F. Gordon, Jr. Conrad and Bean carried the first lunar surface color television camera, but it was damaged when accidentally pointed into the Sun. They made two EVAs totaling 7 hours and 45 minutes. On one, they walked to the Surveyor, photographed it, and removed some parts which they returned to Earth.^[66]

The contracted batch of 15 Saturn Vs were enough for lunar landing missions through Apollo 20. NASA publicized a preliminary list of eight more planned landing sites, with plans to increase the mass of the CSM and LM for the last five missions, along with the payload capacity of the Saturn V. These final missions would combine the I and J types in the 1967 list, allowing the CMP to operate a package of lunar orbital sensors and cameras while his companions were on the surface, and allowing them to stay on the Moon for over three days. These missions would also carry the Lunar Roving Vehicle (LRV), increasing the exploration area and allowing televised liftoff of the LM. Also, the Block II spacesuit was revised for the extended missions to allow greater flexibility and visibility for driving the LRV.

The success of the first two landings allowed the remaining missions to be crewed with a single veteran as Commander, with two rookies. Apollo 13 launched Lovell, Jack Swigert, and Fred Haise in April 1970, headed for the Fra Mauro formation. But two days out, a liquid oxygen tank exploded, disabling the Service Module and forcing the crew to use the LM as a "life boat" to return to Earth. Another NASA review board was convened to determine the cause, which turned out to be a combination of damage of the tank in the factory, and a subcontractor not making a tank component according to updated design specifications.^[29] Apollo was grounded again, for the remainder of 1970 while the oxygen tank was redesigned and an extra one was added.

Mission cutbacks

Main article: Canceled Apollo missions

About the time of the first landing in 1969, it was decided to use an existing Saturn V to launch the Skylab orbital laboratory pre-built on the ground, replacing the original plan to construct it in orbit from several Saturn IB launches; this eliminated Apollo 20. NASA's yearly budget also began to shrink in light of the successful landing, and NASA also had to make funds available for the development of the upcoming Space Shuttle. By 1971, the decision was made to also cancel missions 18 and 19. The two unused Saturn Vs became museum exhibits at the John F. Kennedy Space Center on Merritt Island, Florida, George C. Marshall Space Center in Huntsville, Alabama, Michoud Assembly Facility in New Orleans, Louisiana, and Lyndon B. Johnson Space Center in Houston, Texas.

The cutbacks forced mission planners to reassess the original planned landing sites in order to achieve the most effective geological sample and data collection from the last four missions. Apollo 15 had been planned to be the last of the H series missions, but since there were only two missions left, it was changed to the first of three J missions.

Apollo 13's Fra Mauro mission was reassigned to Apollo 14, commanded in February 1971 by Mercury veteran Alan Shepard, with Stuart Roosa and Edgar Mitchell. This time the mission was successful. Shepard and Mitchell spent 1 day, 9½ hours on the surface, with two EVAs totalling 9 hours 22½ minutes.

Extended missions

Lunar Roving Vehicle used on Apollos 15–17

Apollo 15 was launched in July 1971, with David Scott, Alfred Worden and James Irwin. Scott and Irwin landed near Hadley Rille, and spent just under 2 days, 19 hours on the surface. In over 18 hours of EVA, they collected about 77 kilograms (170 lb) of lunar material.

Plaque left on the Moon by Apollo 17

Apollo 16 landed in the Descartes Highlands in April 1972. The crew was commanded by John Young, with Ken Mattingly and Charles Duke. Young and Duke spent just under 3 days on the surface, with a total of over 20 hours EVA.

Apollo 17 closed out the Apollo program, landing in the Taurus-Littrow region in December 1972. Eugene Cernan commanded Ronald E. Evans and NASA's first scientist-astronaut, geologist Dr. Harrison H. Schmitt. Schmitt was originally scheduled for Apollo 18, but the lunar geological community lobbied for his inclusion on the final lunar landing. Cernan and Schmitt stayed on the surface for just under 3 days, 3 hours and spent just over 23 hours of total EVA.

Mission summary

Main article: List of Apollo missions

Designation	Date	Crew	Description
AS-201	Feb. 26, 1966	None	First flight of Saturn IB and Block I CSM; suborbital to Atlantic ocean; qualified heat shield to orbital reentry speed
AS-203	July 5, 1966	None	No spacecraft; observations of liquid hydrogen fuel behavior in orbit, to support design of S-IVB restart capability
AS-202	Aug. 25, 1966	None	Suborbital flight of CSM to Pacific ocean.
Apollo 4	Nov. 9, 1967	None	First flight of Saturn V; Earth orbital CSM flight; demonstrated S-IVB restart; qualified CM heat shield to lunar reentry speed
Apollo 5	Jan. 22-23, 1968	None	First Earth orbital flight of LM, launched on Saturn IB; demonstrated ascent and descent propulsion; man-rated the LM
Apollo 6	April 4, 1968	None	Attempted demonstration of trans-lunar injection and direct-return abort with SM engine; three engine failures prevented S-IVB restart. Flight controllers used SM engine to repeat Apollo 4's flight profile. Man-rated the Saturn V.
Apollo 7	Oct. 11-22, 1968	Wally Schirra Walt Cunningham Donn Eisele	Earth orbital demonstration of Block II CSM, launched on Saturn IB. First live television publicly broadcast from a manned mission
Apollo 8	Dec. 21-27, 1968	Frank Borman James Lovell William Anders	First manned flight to Moon; CSM made 10 lunar orbits in 20 hours.
Apollo 9	Mar, 3-13, 1969	James McDivitt David Scott Russell Schweickart	Earth orbital demonstration of CSM, LM, and Portable Life Support System used on the lunar surface
Apollo 10	May 18–26, 1969	Thomas Stafford John Young Eugene Cernan	Dress rehearsal for first lunar landing; flew LM down to 50,000 feet (15 km) from lunar surface
Apollo 11	July 16–24, 1969	Neil Armstrong Michael Collins Buzz Aldrin	First manned landing, in Sea of Tranquility. Surface EVA time: 2:31 hr. Samples returned: 47.5 pounds (21.5 kg)
Apollo 12	Nov. 14-24, 1969	C. Peter Conrad Richard Gordon Alan Bean	Second landing, in Ocean of Storms near Surveyor 3 . Surface EVA time: 7:45 hr. Samples returned: 75.7 pounds (34.3 kg)
Apollo 13	April 11–17, 1970	James Lovell Jack Swigert Fred Haise	Third landing attempt aborted near the Moon, due to SM failure. Crew used LM as "life boat" to return to Earth.
Apollo 14	Jan 31-Feb. 9, 1971	Alan Shephard Stuart Roosa Edgar Mitchell	Third landing, in Fra Mauro. Surface EVA time: 9:22 hr. Samples returned: 93.2 pounds (42.3 kg).
Apollo 15	July 26-Aug. 7, 1971	David Scott Alfred Worden James Irwin	First Extended LM and rover, landed in Hadley-Apennine. Surface EVA time:18:34 hr. Samples returned: 170.4 pounds (77.3 kg).
Apollo 16	April 16–27, 1972	John Young T. Kenneth Mattingly Charles Duke	Landed in Plain of Descartes. Surface EVA time: 20:14 hr. Samples returned: 211.0 pounds (95.7 kg).
Apollo 17	Dec. 7-17, 1972	Eugene Cernan Ronald Evans Harrison Schmitt	Landed in Taurus-Littrow. First geologist on the Moon. Surface EVA time: 22:04 hr. Samples returned: 243.6 pounds (110.5 kg).

Source for surface times and sample amounts: NASA: Apollo by the Numbers, Extravehicular Activity

Samples returned

Main article: Moon rock


The most famous of the Moon rocks recovered, the Genesis Rock, returned from Apollo 15.		Ferroan Anorthosite Moon rock, returned from Apollo 16.

The Apollo program returned 841.4 pounds (381.7 kg) of lunar rocks and soil to the Lunar Receiving Laboratory in Houston. Today, most of the samples are stored at the Lunar Sample Laboratory Facility built in 1979.

The rocks collected from the Moon are extremely old compared to rocks found on Earth, as measured by radiometric dating techniques. They range in age from about 3.2 billion years for the basaltic samples derived from the lunar mare, to about 4.6 billion years for samples derived from the highlands crust.^[67] As such, they represent samples from a very early period in the development of the Solar System, that are largely absent on Earth. One important rock found during the Apollo Program is dubbed the Genesis Rock, retrieved by astronauts David Scott and James Irwin during the Apollo 15 mission. This anorthosite rock is composed almost exclusively of the calcium-rich feldspar mineral anorthite, and is believed to be representative of the highland crust. A geochemical component called KREEP was discovered that has no known terrestrial counterpart. KREEP and the anorthositic samples have been used to infer that the outer portion of the Moon was once completely molten (see lunar magma ocean).

Almost all the rocks show evidence of impact process effects. Many samples appear to be pitted with micrometeoroid impact craters, which is never seen on Earth rocks, due to the thick atmosphere. Many show signs of being subjected to high pressure shock waves that are generated during impact events. Some of the returned samples are of impact melt (materials melted near an impact crater.) All samples returned from the Moon are highly brecciated as a result of being subjected to multiple impact events.

Analysis of composition of the lunar samples supports the giant impact hypothesis, that the Moon was created through impact of a large astronomical body with the Earth.^[68]

Program cost

When President Kennedy first chartered the Moon landing program, a preliminary cost estimate of $7 billion was generated, but this proved an extremely unrealistic guess of what could not possibly be determined precisely, and James Webb used his administrator's judgment to change the estimate to $20 billion before giving it to Vice President Johnson.^[69]

Webb's estimate shocked many at the time (including the President), but ultimately proved to be reasonably accurate. In January 1969, NASA prepared an itemized estimate of the run-out cost of the Apollo program. The total came to $23.9 billion, itemized as follows:^[70]

Apollo spacecraft: $7,945.0 million
Saturn I launch vehicles: $767.1 million
Saturn IB launch vehicles: $1,131.2 million
Saturn V launch vehicles: $6,871.1 million
Launch vehicle engine development: $854.2 million
Mission support: $1,432.3 million
Tracking and data acquisition: $664.1 million
Ground facilities: $1,830.3 million
Operation of installations: $2,420.6 million.

The final cost of project Apollo was reported to Congress as $25.4 billion in 1973.^[71] It took up the majority of NASA's budget while it was being developed. For example, in 1966 it accounted for about 60 percent of NASA's total $5.2 billion budget.^[72] A single Saturn V launch in 1969 cost up to $375 million, compared to the National Science Foundation's fiscal year 1970 budget of $440 million.^[73]

In 2009, NASA held a symposium on project costs which presented an estimate of the Apollo program costs in 2005 dollars as roughly $170 billion. This included all research and development costs; the procurement of 15 Saturn V rockets, 16 Command/Service Modules, 12 Lunar Modules, plus program support and management costs; construction expenses for facilities and their upgrading, and costs for flight operations. This was based on a Congressional Budget Office report, A Budgetary Analysis of NASA’s New Vision for Space, September 2004.^[69] The Space Review estimated in 2010 the cost of Apollo from 1959 to 1973 as $20.4 billion, or $109 billion in 2010 dollars, averaged over the six landings as $18 billion each.^[74]

Apollo Applications Program

Main article: Apollo Applications Program

Looking beyond the manned lunar landings, NASA investigated several post-lunar applications for Apollo hardware. The Apollo Extension Series (Apollo X,) proposed up to 30 flights to Earth orbit, using the space in the Spacecraft-LM Adapter to house a small orbital laboratory (workshop). Astronauts would continue to use the CSM as a ferry to the station. This study was followed by design of a larger orbital workshop to be built in orbit from an empty S-IVB Saturn upper stage, and grew into the Apollo Applications Program (AAP). The workshop was to be supplemented by Apollo Telescope Missions, which would replace the LM's descent stage equipment and engine with a solar telescope observatory. The most ambitious plan called for using an empty S-IVB as an interplanetary spacecraft for a Venus fly-by mission.

The S-IVB orbital workshop was the only one of these plans to make it off the drawing board. Dubbed Skylab, it was constructed complete on the ground rather than in space, and launched in 1973 using the two lower stages of a Saturn V. It was equipped with an Apollo Telescope Mount, the solar telescope that would have been used on the Apollo Telescope Missions. Skylab's last crew departed the station on February 8, 1974, and the station itself re-entered the atmosphere in 1979, by which time it had become the oldest operational Apollo-Saturn component.

Recent observations

“There the [Apollo 11] lunar module sits, parked just where it landed 40 years ago, as if it still really were 40 years ago and all the time since merely imaginary.” –The New York Times^[75]

In 2008, Japan Aerospace Exploration Agency's SELENE probe observed evidence of the halo surrounding the Apollo 15 lunar module blast crater while orbiting above the lunar surface.^[76] In 2009, NASA's robotic Lunar Reconnaissance Orbiter, while orbiting 50 kilometres (31 mi) above the Moon, photographed the remnants of the Apollo program left on the lunar surface, and photographed each site where manned Apollo flights landed.^[77]^[78] All of the U. S. flags left on the moon during the Apollo missions were found to still be standing, with the exception of the one left during the Apollo 11 mission, which was blown over during that mission's lift-off from the lunar surface and return to the mission command module in lunar orbit; the degree to which these flags retain their original colors remains unknown.^[79]

In a November 16, 2009 editorial, The New York Times opined:

[T]here's something terribly wistful about these photographs of the Apollo landing sites. The detail is such that if Neil Armstrong were walking there now, we could make him out, make out his footsteps even, like the astronaut footpath clearly visible in the photos of the Apollo 14 site. Perhaps the wistfulness is caused by the sense of simple grandeur in those Apollo missions. Perhaps, too, it’s a reminder of the risk we all felt after the Eagle had landed – the possibility that it might be unable to lift off again and the astronauts would be stranded on the Moon. But it may also be that a photograph like this one is as close as we’re able to come to looking directly back into the human past.^[75]

In September 2007, the X Prize Foundation and Google announced the Google Lunar X Prize, to be awarded for a robotic lunar landing mission which transmits close-up images of the Apollo Lunar Modules and other artificial objects on the surface.^[80]

Legacy

Science and engineering

Further information: NASA spinoff technologies

The Apollo program has been called the greatest technological achievement in human history.^[81]^[82] Apollo stimulated many areas of technology. The flight computer design used in both the lunar and command modules was, along with the Minuteman Missile System, the driving force behind early research into integrated circuits. The first practical fuel cell was developed for this program. Computer-controlled machining was first used in the fabrication of Apollo structural components.

Cultural impact

The Earth over the lunar horizon, photographed by the Apollo 8 crew

"Everything that I ever knew – my life, my loved ones, the Navy – everything, the whole world was behind my thumb." –James Lovell

The crew of Apollo 8 sent the first live televised pictures of the Earth and the Moon back to Earth, and read from the creation story in the Biblical book of Genesis, on Christmas Eve, 1968, This was believed to be the most widely watched television broadcast until that time. The mission and Christmas provided an inspiring end to 1968, which had been a bad year for the U.S., marked by Vietnam War protests, race riots, and the assassinations of civil rights leader Martin Luther King, Jr., and Senator Robert Kennedy.

An estimated one-fifth of the population of the world watched the live transmission of the first Apollo Moon walk.^[83]

"We went to explore the Moon, and in fact discovered the Earth." –Eugene Cernan

An effect of the Apollo program is the view of Earth as a fragile, small planet, captured in photographs taken by the astronauts during the lunar missions. The most famous, taken by the Apollo 17 astronauts, is The Blue Marble (right).

Many astronauts and cosmonauts have commented on the profound effects that seeing Earth from space has had on them;^[84]^{[broken citation]} the 24 astronauts who traveled to the Moon are the only humans to have observed Earth from beyond low Earth orbit, and have traveled farther from Earth than anyone else to date.

According to The Economist, Apollo succeeded in accomplishing President Kennedy's goal of taking on the Soviet Union in the Space Race, and beat it by accomplishing a singular and significant achievement, and thereby showcased the superiority of the capitalistic, free-market system as represented by the US. The publication noted, however, the irony that in order to achieve the goal, the program required the organization of tremendous public resources within a vast, centralized government bureaucracy.^[85]

Apollo 11 broadcast data restoration project

As part of Apollo 11's 40th anniversary in 2009, NASA spearheaded an effort to digitally restore the existing videotapes of the mission's live televised moonwalk.^[86] After an exhaustive three-year search for missing tapes of the original video of the Apollo 11 moonwalk, NASA concluded the data tapes had more than likely been accidentally erased.^[87]

We're all saddened that they're not there. We all wish we had 20-20 hindsight. I don't think anyone in the NASA organization did anything wrong, I think it slipped through the cracks, and nobody's happy about it.

—Dick Nafzger, TV Specialist, NASA Goddard Space Flight Center^[87]

The Moon landing data was recorded by a special Apollo TV camera which recorded in a format incompatible with broadcast TV. This resulted in lunar footage that had to be converted for the live television broadcast and stored on magnetic telemetry tapes. During the following years, a magnetic tape shortage prompted NASA to remove massive numbers of magnetic tapes from the National Archives and Records Administration to be recorded over with newer satellite data. Stan Lebar, who designed and built the lunar camera at Westinghouse Electric Corporation, also worked with Nafzger to try to locate the missing tapes.^[87]

So I don't believe that the tapes exist today at all. It was a hard thing to accept. But there was just an overwhelming amount of evidence that led us to believe that they just don't exist anymore. And you have to accept reality.

—Stan Lebar, Lunar Camera Designer, Westinghouse Electric Corporation^[87]

With a budget of $230,000, the surviving original lunar broadcast data from Apollo 11 was compiled by Nafzger and assigned to Lowry Digital for restoration. The video was processed to remove random noise and camera shake without destroying historical legitimacy.^[88] The images were from tapes in Australia, the CBS News archive, and kinescope recordings made at Johnson Space Center. The restored video, remaining in black and white, contains conservative digital enhancements and did not include sound quality improvements.^[88]

Depictions on film

Documentaries

Numerous documentary films cover the Apollo program and the Space Race, including:

Moonwalk One (1970)
For All Mankind (1989)
Moon from the BBC miniseries The Planets (1999)
Magnificent Desolation: Walking on the Moon 3D (2005)
In the Shadow of the Moon (2007)
When We Left Earth: The NASA Missions (miniseries) (2008)
James May on the Moon (documentary commemorating 40 years since the landings) (2009)
NASA's Story (2009)
Moonscape (freely downloadable Apollo 11 documentary) (2012)

Docudramas

The Apollo program, or certain missions, have been dramatized in Apollo 13 (film) (1995), Apollo 11 (film) (1996), From the Earth to the Moon (TV miniseries) (1998), Space Race (2005), and Moon Shot (film) (2009).

Retro-Reflectivity on the moon

(glossary entry)

Retro-Reflectivity on the moon

Description

Additional Information

Causes

The "classic" Heiligenschein on Terrestrial surfaces

Lunar Retro-reflectivity Observed from Earth

The Lunar Heiligenschein observed in orbit around the Moon

The Lunar Heiligenschein observed from the Moon's surface

Variation with types of topography

Observations of reflected sunlight in shadowed craters

Other things attributed to lunar retro-reflectivity

Other examples of Retro-Reflectivity

Specular reflections from the Moon?

LPOD Articles

EPOD Articles

Bibliography

Retro-Reflection/ "Heiligenschein" (general)

Lunar Retroreflectivity

Description

Retro-reflectivity refers to the reflection of light back towards the source from which it originates. Like many natural surfaces, the Moon's surface reflects considerably more light back in this direction than would, say, a diffuse reflector like a sheet of paper or a surface sprayed with "flat" paint. One of the many manifestations of this is that the Full Moon (which is always viewed with the Sun "at our backs") is considerably brighter than might be expected from its surface brightness at other phases. Another is the "hot spots" seen in many photos taken from lunar orbit, where a bright patch is seen in the direction opposite the Sun (where one would expect to see the shadow of the spacecraft, if it were large enough to be visible). Yet another is the halo of light seen around the shadow of the head of an astronaut photographing his own shadow at close range.

The term retro-reflectivity can also be applied (less correctly) to sun-glints from large shiny surfaces. In this case, a strong flash of brightness (more properly called a specular reflection) is seen when the light source, surface and observer are at exactly the right angles (not necessarily 180°) to allow the surface to act as a mirror, shining the light into the observer's eyes. Specular reflections from flat or aligned surfaces on the Moon have been offered as a possible cause for some of the so-called Transient Lunar Phenomena. Although sun glints of this kind have been seen on Mars, none of the reported transient lunar brightenings has ever repeated when viewed again at the same combination of angles.

Additional Information

Causes

The moon's surface is covered by a layer of dust, called the regolith. This dust layer is thought to be the primary cause of the Moon's retro-reflectivity (an optical effect sometimes called the Lunar Heiligenschein). The hiding of shadows from coarser structures, like surface rocks and boulders may also play a role.

The "classic" Heiligenschein on Terrestrial surfaces

The term Heiligenschein (German for the "saintly glow"), sometimes used to describe the glow of the lunar retro-reflectivity, especially when seen around the shadow of an astronaut's head, is derived from a similar-appearing phenomenon observable on many of the Earth's surfaces. In particular, it was originally used to describe the diffuse colorless glow seen around the shadow of one's own head cast on dew-covered grass. It is sometimes also called the "Sylvanshine" and/or "Heiligenschein Streak" for the vertical column that is sometimes seen above the shadow of the observer's head. The so-called "Glory" (also around the anti-solar point) is a different phenomenon exhibiting spectral colors. The explanation of this rainbow-related effect can be found on many websites or books.

Lunar Retro-reflectivity Observed from Earth

The condition of illumination responsible for the retro-reflectivity is most conveniently described by something called the phase angle (the angle between the observer and the Sun as seen from the lunar surface).
The Moon exhibits both an increase in reflectance as the phase angle gets smaller, and an additional opposition surge in brightness as the phase angle approaches zero. The strength of the retro-reflectivity can be appreciated by comparing its behavior to an idealized diffuse reflector. If the Moon were a diffuse reflector, its total brightness (the intensity of the moonlight falling on the Earth) would be expected to increase by a factor of pi (3.14) in going from First Quarter (phase angle 90°) to Full (phase angle 180°). The actual increase is said to be more like a factor of 14 with perhaps as much as 40% of this, or so, occurring in the last 5°.
When the Moon is observed from Earth, the entire lunar surface is at a similar phase angle (within about 0.5°); and the maximum amount of the Moon's retro-reflectivity is difficult to observe because when the Sun is directly behind the observer, the Earth's shadow is cast on the Moon, creating an eclipse.

The Lunar Heiligenschein observed in orbit around the Moon

Photographs taken from lunar orbit differ from those obtained from Earth in that the range of phase angles is typically quite large; and when looking a direction opposite the Sun, the shadow cast by the spacecraft is quite small. Hence one can observe the appearance of a small part of the lunar surface at essentially zero phase angle, and neighboring regions at increasing phase angles.
If the counter-solar point (at an angle of 180° from the Sun, also known as the opposition point) is located on the Moon's surface, this point will be marked by a very bright diffuse spot (the "Heiligenschein" without central shadow!). Many of the orbital Fairchild metric (mapping) photographs, made during Apollo missions 15, 16, and 17 show this effect very well! To discover the lunar "Heiligenschein", one should look for shadow-less photographs (photographs which show only albedo differences).
Looking at a single photo can easily give the incorrect impression that a crater is surrounded by a bright halo, when in fact it is only temporarily located at the center of the opposition surge.
Because of the large range of phase angles available in a single image, the Apollo orbital photos gave the first quantitative estimates of the magnitude and angular range of the lunar opposition surge, although the results were not always consistent.
The following sequence of oblique metric views from Apollo 15 is a typical one showing the bright retro-reflecting anti-solar point (the blue arrow) tracking the motion of the spacecraft over southern Mare Serenitatis and into the Littrow highlands area (the spacecraft actually took the photos while moving from right to left).

A Sequence of Oblique Metric Photos -- click to enlarge

It is not known if these photos all have the same processing, but they make it appear that the opposition surge varies both in brightness and angular size as it moves over different kinds of terrain. It looks to be at its most concentrated in the third view from the left, where it appears to be about the same size as the crater Clerke (just to the right of the tip of the red arrow). At a viewing distance of about 180 km, this 6 km apparent diameter translates into an angular size of about 2° (a cone angle of 1° around the anti-solar point). Note also how the Catena Littrow area (pointed to by the red arrow), flares strongly in brightness in the second and third frames (even though it is 5-10° away from the anti-solar point), and how the bright rays on the floor of Mare Serenitatis brighten and fade as the anti-solar point moves over them..

The Lunar Heiligenschein observed from the Moon's surface

Photographs taken by astronauts or by spacecraft on the lunar surface show an even larger range of phase angles than those taken from orbit.
When the Apollo astronauts walked on the moon's surface, they noticed a bright diffuse "glow" around the shadow of their head. The shadows of their heads were always located at the centre of the Heiligenschein (at 180° of the sun). Several of the Hasselblad photographs, made on the moon's surface, show this glow centered at the point where the phase angle approaches zero (the shadow of the camera taking the photo). A similar glow was noticed when the astronauts were inside the Lunar Module. The shadow of the LM's upper part was surrounded by the Lunar Heiligenschein.
AS12-48-7026, made during the mission of Apollo 12, shows the Lunar Heiligenschein around the upper part of LM Intrepid's shadow.
AS17-136-20744, made during the mission of Apollo 17, shows the shadow of an astronaut, surrounded by the Lunar Heiligenschein (around the upper part of the shadow). These photographs (AS12-48-7026 and AS17-136-20744) are included in the book Full Moon by Michael Light and Andrew Chaikin. The printed versions of these photographs (Plates 44 and 45) show much more brightness contrast than the online scans.
AS17-140-21359 is another typical Hasselblad of an astronaut's Lunar Heiligenschein. Note the absence of shadows at small rocks around the astronaut's shadow, indicating one is looking along the direction of the sunlight. The increase in brightness at this viewing angle is in part due to this Shadow Hiding effect. This photograph is also included in the book Full Moon by Michael Light and Andrew Chaikin, as Plate 99.
AS12-46-6841 is probably one of the most interesting photographs of the Lunar Heiligenschein. This photograph was made at Middle Crescent crater (Apollo 12 site). Note the long shadows of astronauts Pete Conrad and Alan Bean. The haze-like smudge in the centre of the photograph is due to dust on the Hasselblad-camera's lens.

Variation with types of topography

It seems obvious that different kinds of lunar surface features respond differently to the changing illumination during the lunar cycle. For example, the bright lunar rays are most readily visible near Full Moon, implying that they brighten more than the rest of the surface.
Wildey (1978) produced a black and white image of the whole Moon that purports to highlight the regions that exhibit the greatest (and least) surge in brightness in the hours immediately around Full Moon. Plates at a phase angle of about 2 degrees were apparently compared to others taken at around 4 degrees. He claims the greatest opposition surges are around Aristarchus and at Cassini’s Bright Spot. Bright rays in general were not found to have an unusually large opposition surge (although evidently the have a greater overall brightening than most of the Moon).
Others have followed Wildey, typically forming ratios of Clementine images taken at zero and non-zero phase angles.

Observations of reflected sunlight in shadowed craters

On page 18 of H.P.Wilkins's and P.Moore's book The Moon:
- "...after all, it is not surprising that detail can occasionally be seen on the unilluminated portion, so much light is sometimes reflected from the surrounding sunlit cliffs or walls that Dr. W.H. Steavenson, using a shaded eyepiece, has seen the central mountains of the craters Agrippa and Godin when the interior of the crater was filled with shadow, and even noted the short shadow cast by the central mountains owing to the light reflected on to them by the cliffs".

Other things attributed to lunar retro-reflectivity

O'Keefe (1957) suggested that the brightness in lunar rays was due to their being composed of transparent glass-spherules, producing a retro-reflection effect like a bead-coated projector screen.
The ability to sometimes see detail in the shadowed parts of an Apollo astronaut's suit while walking on the Moon has sometimes been attributed to the shadowed part of the white suit receiving retro-reflected light from the bright Lunar Heiligenschein around the astronaut's shadow on the retro-reflective regolith. A typical Hasselblad photograph which shows the "not shadow-like" or "not dark shadow" on an Apollo astronaut's suit is AS16-117-18825 (Apollo 16's John Young, near the Lunar Roving Vehicle). But this explanation cannot be correct for several reasons. The light from the opposition surge on the lunar soil is not like the beam from a flashlight. Even if the reflected light were 50% stronger than normal over a 5° angle, that little zone is no more than 0.4% of the total hemisphere into which light is reflected and hence it augments the overall reflectivity by only about 0.2%. The remaining 99.8% of the light reflected by the lunar soil is spread over a larger range of angles and similar to what one would expect from an ordinary diffusely reflecting surface. The detail visible in the shadowed parts of the astronaut's suit is presumably lit by a variety of sources including this diffuse reflection from the surface. Note that photos of astronauts walking in space, above the Earth or Moon, where their shadows are lost in space (and hence there cannot be reflections from the anti-solar point) show similar detail in the shadowed areas. In part this is because of the whiteness of their suit compared to the relatively low reflectance surfaces on which many of the other shadows fall. As further proof, many Apollo photos show detail in the shadowed side of small rocks and boulders lying directly on the lunar surface. If the shadowed sides of these rocks were lit primarily by small-angle retro-reflections we would expect to see a bright fringe around the sunlit edge (where the returning retro-reflected light would strike) and a dark interior (where no retro-reflected rays could strike). Instead, when the face of the rock is flat we see the entire shadowed side illuminated by a uniform light, evidently produced by the general wide-angle reflections from the lunar surface.

Other examples of Retro-Reflectivity

"Cat's eye" reflectors on bicycles and cars (also called cube-corner reflectors).
Similar (but much more precise) arrays of cube-corner reflectors (LRRR's) were left on the Moon by three Apollo and two Russian missions, and form the basis for an on-going Lunar Laser Ranging Experiment which monitors changes in the distance between Earth and Moon to unprecedented accuracy. The locations of the LRRR's are also among the most precisely known positions on the Moon. See the photograph of the Apollo 11 LRRR on the lunar surface at Statio Tranquillitatis. The fact that the reflections from the aluminized(?) surfaces of these carefully crafted quartz corners can be detected against the background of the lunar soil clearly demonstrates that the general retro-reflectivity of the Moon is of a much lower order.
Movie projector screens, made of a white plastic sheet with millions of small transparent glass-spherules on it (an equivalent of the dew-drop Heiligenschein on grass) (see Bibliography).
Road traffic signs (made of minuscule cube-corner reflectors, or transparent glass-spherules).
White paint on roads (contains millions of small transparent glass-spherules, the same effect as the Movie screens).
The temporary brightness enhancement of Saturn's rings when this planet is at opposition (a Shadow Hiding effect). This effect (a temporary brightness enhancement) is noticeable on all the outer solar system's planets when they are at opposition. Not on Mercury and Venus because they are behind the sun when they are at "Full".
The Gegenschein (the Opposition effect) on the solar system's cloud of asteroids and meteoroid-dust (a diffuse glow at 180° away of the sun).
The visibility of the moon's near side when there's a Total Solar Eclipse (!). This is the so-called Ashen-light which is also visible before First Quarter Moon ("young moon") and after Last Quarter Moon ("old moon"). During a Total Solar Eclipse, the moon's near side is like a "Full Moon" (not illuminated by the Sun, but rather by the reflected sunlight of the "Full Earth"!).
- Note: the Earth probably does not show a large opposition surge as viewed from the Moon, so the intensity of the Earthshine during a Total Solar Eclipse is probably not much greater than at any other time near a New Moon. The Earthshine gives the Moon's nearside a constant, but very dim, Full Moon-like component as viewed from Earth, whose intensity varies during the lunar cycle, going to near zero near Full Moon (when the Earth is dark as seen from the Moon). The Earthshine component always enjoys the full retro-reflectivity of the lunar surface, since we are viewing from less than 1° away from the light source (the sunlit parts of the Earth, as seen from the Moon). It can most readily seen a few days before or after New Moon, when it is still relatively bright, but can be seen (near Moonrise/Moonset) in a relatively dark sky. - JimMosher
- The Apollo astronauts orbiting the Moon were easily able to see the lunar landscape illuminated by the Earthshine, and were able to detect its "terminator" (which is always located at the extreme limit of what we can see from Earth). The part of the Moon that was illuminated by neither sunlight nor Earthshine was extremely dark and showed no detail. - JimMosher

Specular reflections from the Moon?

The most creditable search for shiny reflective surfaces on the Moon seems to be part of the joint ALPO/BAA transient effects effort directed by British astronomer Anthony Cook. Cook publishes monthly forecasts of places and times when past reports of localized lunar brightenings (and other kinds of events) can be re-observed under a nearly identical viewing geometry. The results are sometimes reported in ALPO’s The Lunar Observer newsletter. To the best of my knowledge nothing that could be attributed to a repeating specular reflection from a shiny surface on the Moon has ever been observed. - JimMosher

LPOD Articles

Bright Targets (Full Moon photography)

EPOD Articles

Earthshine from Eclipse Lunar Crescent and Earthshine

Bibliography

Retro-Reflection/ "Heiligenschein" (general)

Les Cowley's Atmospheric Optics website (explaining the dewdrop form of the Heiligenschein).
M.G.J. Minnaert's Light and Color in the Outdoors (De Natuurkunde Van 't Vrije Veld).

Lunar Retroreflectivity

(see also opposition surge)

John O'Keefe. 1957. Lunar Rays. Astrophysical Journal, 126:466 (an excerpt of this article was printed on pages 214 and 215 of the book Mysterious Universe; a handbook of astronomical anomalies (1979), by the underestimated explorer and investigator of odd scientific discoveries: W.R.Corliss).
Robert Wildey. 1978. The Moon in Heiligenschein. Science Vol. 200, pp. 1265-1267.

sábado, 12 de enero de 2013

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