Apollo program (Kaiserreich: Legacy of the Weltkrieg)

The Apollo program, also known as Project Apollo, is the third and current United States human spaceflight program carried out by the National Aeronautics and Space Administration (NASA), which succeeded in preparing and landing the first humans on the Moon in 1969. It was first conceived during Estes Kefauver's administration as a three-person spacecraft to follow the one-person Project Mercury, which put the first humans in space. Apollo was later dedicated to President John F. Kennedy's national goal for the 1960s of "landing a man on the Moon and returning him safely to the Earth" in an address to Congress on May 25, 1961. It was the third US human spaceflight program to fly, preceded by the two-person Project Gemini conceived in 1961 to extend spaceflight capability in support of Apollo.
Kennedy's goal was accomplished on the Apollo 11 mission when astronauts Neil Armstrong and Buzz Aldrin landed their Apollo Lunar Module (LM) on July 20, 1969, and walked on the lunar surface, while Michael Collins remained in lunar orbit in the command and service module (CSM), and all three landed safely on Earth on July 24.
Apollo has continuously run since 1961, with the first crewed flight in 1967. It is the longest-running manned program in the world.
Apollo set several major human spaceflight milestones. It stands alone in sending crewed missions beyond low Earth orbit. Apollo 8 was the first crewed spacecraft to orbit another celestial body, and Apollo 11 was the first crewed spacecraft to land humans on one.
Apollo has spurred advances in many areas of technology incidental to rocketry and human spaceflight, including avionics, telecommunications, and computers.
== Background ==
=== Origin and spacecraft feasibility studies ===
The Apollo program was conceived during the Kefauver administration in early 1960, as a follow-up to Project Mercury. While the Mercury capsule could support only one astronaut on a limited Earth orbital mission, Apollo would carry three and possibly more. Possible missions included ferrying crews to a space station, circumlunar flights, and eventual crewed lunar landings.
The program was named after Apollo, the Greek god of light, music, and the Sun, by NASA manager Abe Silverstein, who later said, "I was naming the spacecraft like I'd name my baby." Silverstein chose the name at home one evening, early in 1960, because he felt "Apollo riding his chariot across the Sun was appropriate to the grand scale of the proposed program."
In July 1960, NASA Deputy Administrator Hugh L. Dryden announced the Apollo program to industry representatives at a series of Space Task Group conferences. Preliminary specifications were laid out for a spacecraft with a mission module cabin separate from the command module (piloting and reentry cabin), and a propulsion and equipment module. On August 30, a feasibility study competition was announced, and on October 25, three study contracts were awarded to General Dynamics/Convair, General Electric, and the Glenn L. Martin Company. Meanwhile, NASA performed its own in-house spacecraft design studies led by Maxime Faget, to serve as a gauge to judge and monitor the three industry designs.
=== Political pressure builds ===
In November 1960, John F. Kennedy was elected president after a campaign that promised American superiority over Germany in the fields of space exploration and missile defense. Up to the election of 1960, Kennedy had been speaking out against the "missile gap" that he and many other senators felt had developed between Germany and the United States due to the inaction of President Kefauver. Beyond military power, Kennedy used aerospace technology as a symbol of national prestige, pledging to make the US not "first but, first and, first if, but first period". Despite Kennedy's rhetoric, he did not immediately come to a decision on the status of the Apollo program once he became president. He knew little about the technical details of the space program, and was put off by the massive financial commitment required by a crewed Moon landing. When Kennedy's newly appointed NASA Administrator James E. Webb requested a 30 percent budget increase for his agency, Kennedy supported an acceleration of NASA's large booster program but deferred a decision on the broader issue.
On April 12, 1961, the Germans attempted to launch an astronaut into space; the rocket carrying Yuri Gagarin exploded on the launch pad, but the very fact that the Germans had come so close reinforced American fears about being left behind in a technological competition with Germany. At a meeting of the US House Committee on Science and Astronautics one day after Gagarin's death, many congressmen pledged their support for a crash program aimed at ensuring that America would catch up. Kennedy was circumspect in his response to the news, refusing to make a commitment on America's response to the Germans.
On April 20, Kennedy sent a memo to Vice President Lyndon B. Johnson, asking Johnson to look into the status of America's space program, and into programs that could offer NASA the opportunity to catch up. Johnson responded approximately one week later, concluding that "we are neither making maximum effort nor achieving results necessary if this country is to reach a position of leadership." His memo concluded that a crewed Moon landing was far enough in the future that it was likely the United States would achieve it first.
On May 25, 1961, twenty days after the first successful manned spaceflight Mercury 3, Kennedy proposed the crewed Moon landing in a Special Message to the Congress on Urgent National Needs:
Now it is time to take longer strides—time for a great new American enterprise—time for this nation to take a clearly leading role in space achievement, which in many ways may hold the key to our future on Earth.
... I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth. No single space project in this period will be more impressive to mankind, or more important in the long-range exploration of space; and none will be so difficult or expensive to accomplish.
== 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. By 1963, Kennedy even came close to agreeing to a joint US-German Moon mission, to eliminate duplication of effort.
With the clear goal of a crewed landing replacing the more nebulous goals of space stations and circumlunar flights, NASA decided that, in order to make progress quickly, it would discard the feasibility study designs of Convair, GE, and Martin, and proceed with Faget's command and service module design. The mission module was determined to be useful only as an extra room, and therefore unnecessary. They used Faget's design as the specification for another competition for spacecraft procurement bids in October 1961. On November 28, 1961, it was announced that North American Aviation had won the contract, although its bid was not rated as good as Martin's. Webb, Dryden and Robert Seamans chose it in preference due to North American's longer association with NASA and its predecessor.
Landing humans on the Moon by the end of 1969 required the most sudden burst of technological creativity, and the largest commitment of resources ($25 billion; $158 billion in 2020 US dollars) 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.
On July 1, 1960, NASA established the Marshall Space Flight Center (MSFC) in Huntsville, Alabama. MSFC designed the heavy lift-class Saturn launch vehicles, which would be required for Apollo.
=== Manned Spacecraft Center ===
It became clear that managing the Apollo program would exceed the capabilities of Robert R. Gilruth's Space Task Group, which had been directing the nation's crewed 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. 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.
In September 1962, by which time four 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...
The MSC was completed in September 1963. It was renamed by the US Congress in honor of Lyndon Johnson soon after his death in 1973.
=== Launch Operations 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 crewed 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. Construction began in November 1962. Following Kennedy's death, President Johnson issued an executive order on November 29, 1963, to rename the LOC and Cape Canaveral in honor of Kennedy.
The LOC included Launch Complex 39, a Launch Control Center, and a 130-million-cubic-foot (3,700,000 m3) Vertical Assembly Building (VAB). in which the space vehicle (launch vehicle and spacecraft) would be assembled on a mobile launcher platform and then moved by a crawler-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.
=== 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) Seamans to reorganize the Office of Manned Space Flight (OMSF). On July 23, 1963, Webb announced Mueller's appointment as Deputy Associate Administrator for Manned Space Flight, to replace then Associate Administrator D. Brainerd 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) reported to Mueller.
Based on his industry experience on Air Force missile projects, Mueller realized some skilled managers could be found among high-ranking officers in the U.S. 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's superior officer Bernard A. 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 human landing in July 1969, after which he returned to Air Force duty.
== Choosing a mission mode ==
Once Kennedy had defined a goal, the Apollo mission planners were faced with the challenge of designing a spacecraft 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: The spacecraft would be launched as a unit and travel directly to the lunar surface, without first going into lunar orbit. A 50,000-pound (23,000 kg) Earth return ship would land all three astronauts atop a 113,000-pound (51,000 kg) descent propulsion stage, which would be left on the Moon. This design would have required development of the extremely powerful Saturn C-8 or Nova launch vehicle to carry a 163,000-pound (74,000 kg) payload to the Moon.
* Earth Orbit Rendezvous (EOR): Multiple rocket launches (up to 15 in some plans) would carry parts of the Direct Ascent spacecraft and propulsion units for translunar injection (TLI). These would be assembled into a single spacecraft in Earth orbit.
* 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 crewed vehicle. Propellant would have to be transferred from the automated vehicle to the crewed vehicle.
* Lunar Orbit Rendezvous (LOR): This turned out to be the winning configuration, which achieved the goal with Apollo 11 on July 24, 1969: a single Saturn V launched a 96,886-pound (43,947 kg) spacecraft that was composed of a 63,608-pound (28,852 kg) Apollo command and service module which remained in orbit around the Moon and a 33,278-pound (15,095 kg) two-stage Apollo Lunar Module spacecraft which was flown by two astronauts to the surface, flown back to dock with the command module and was then discarded. Landing the smaller spacecraft on the Moon, and returning an even smaller part (10,042 pounds or 4,555 kilograms) to lunar orbit, minimized the total mass to be launched from Earth, but this was the last method initially considered because of the perceived risk of rendezvous and docking.
In early 1961, direct ascent was generally the mission mode in favor at NASA. Many engineers feared that rendezvous and docking, maneuvers that had not been attempted in Earth orbit, would be nearly impossible in lunar orbit. LOR advocates including John Houbolt at Langley Research Center emphasized the important weight reductions that were offered by the LOR approach. Throughout 1960 and 1961, Houbolt campaigned for the recognition of LOR as a viable and practical option. Bypassing the NASA hierarchy, he sent a series of memos and reports on the issue to Associate Administrator Robert Seamans; while acknowledging that he spoke "somewhat as a voice in the wilderness", Houbolt pleaded that LOR should not be discounted in studies of the question.
Seamans's establishment of an ad hoc committee headed by his special technical assistant Nicholas E. Golovin in July 1961, to recommend a launch vehicle to be used in the Apollo program, represented a turning point in NASA's mission mode decision. This committee recognized that the chosen mode was an important part of the launch vehicle choice, and recommended in favor of a hybrid EOR-LOR mode. Its consideration of LOR—as well as Houbolt's ceaseless work—played an important role in publicizing the workability of the approach. In late 1961 and early 1962, members of the Manned Spacecraft Center began to come around to support LOR, including the newly hired deputy director of the Office of Manned Space Flight, Joseph Shea, who became a champion of LOR. The engineers at Marshall Space Flight Center (MSFC), which had much to lose from the decision, took longer to become convinced of its merits, but their conversion was announced by Wernher von Braun at a briefing on June 7, 1962.
But even after NASA reached internal agreement, it was far from smooth sailing. Kennedy's science advisor Jerome Wiesner, who had expressed his opposition to human spaceflight to Kennedy before the President took office, and had opposed the decision to land people on the Moon, hired Golovin, who had left NASA, to chair his own "Space Vehicle Panel", ostensibly to monitor, but actually to second-guess NASA's decisions on the Saturn V launch vehicle and LOR by forcing Shea, Seamans, and even Webb to defend themselves, delaying its formal announcement to the press on July 11, 1962, and forcing Webb to still hedge the decision as "tentative".
Wiesner kept up the pressure, even making the disagreement public during a two-day September visit by the President to Marshall Space Flight Center. Wiesner blurted out "No, that's no good" in front of the press, during a presentation by von Braun. Webb jumped in and defended von Braun, until Kennedy ended the squabble by stating that the matter was "still subject to final review". Webb held firm and issued a request for proposal to candidate Lunar Excursion Module (LEM) contractors. Wiesner finally relented, unwilling to settle the dispute once and for all in Kennedy's office, because of the President's involvement with the October Cuban Missile Crisis, and fear of Kennedy's support for Webb. NASA announced the selection of Grumman as the LEM contractor in November 1962.
Space historian James Hansen concludes that:
Without NASA's adoption of this stubbornly held minority opinion in 1962, the United States may still have reached the Moon, but almost certainly it would not have been accomplished by the end of the 1960s, President Kennedy's target date.
The LOR method had the advantage of allowing the lander spacecraft to be used as a "lifeboat" in the event of a failure of the command ship. Some documents prove this theory was discussed before and after the method was chosen. In 1964 an MSC study concluded, "The LM [as lifeboat] ... was finally dropped, because no single reasonable CSM failure could be identified that would prohibit use of the SPS." Ironically, just such a failure happened on Apollo 13 when an oxygen tank explosion left the CSM without electrical power. The lunar module provided propulsion, electrical power and life support to get the crew home safely.
== Spacecraft ==
Faget's preliminary Apollo design employed a cone-shaped command module, supported by one of several service modules providing propulsion and electrical power, sized appropriately for the space station, cislunar, and lunar landing missions. Once Kennedy's Moon landing goal became official, detailed design began of a command and 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, after being soft-landed by a larger landing propulsion module. The final choice of lunar orbit rendezvous changed the CSM's role to the translunar ferry used to transport the crew, along with a new spacecraft, the Lunar Excursion Module (LEM, later shortened to LM (Lunar Module) but still pronounced /ˈlɛm/) which would take two individuals to the lunar surface and return them to the CSM.
=== Command and service module ===
The command module (CM) is 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 is covered with an ablative heat shield, and has its own reaction control system (RCS) engines to control its attitude and steer its atmospheric entry path. Parachutes are carried to slow its descent to splashdown. The module is 11.42 feet (3.48 m) tall, 12.83 feet (3.91 m) in diameter, and weighs approximately 12,250 pounds (5,560 kg).
A cylindrical service module (SM) supports 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 reentry. 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).
There exist two versions of the Apollo CSM: the Apollo SR (Short Range) and Apollo LR (Long Range). The Apollo SR was proposed in 1963 as a less-capable version of the baseline design (later given the Apollo LR designation) for space station operations. The Apollo SR has a smaller, lighter service module roughly half the length of the LR service module, and deployable solar panels. The Apollo SR was approved in March 1964.
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 the Moon, and thus was oversized to about twice the thrust required for translunar flight (the service propulsion engine on the Apollo SR is more appropriate for translunar flight). 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 production spacecraft, would incorporate the docking equipment and take advantage of the lessons learned in Block I development. The Block I designation was applied to both the SR and LR spacecraft, with the Block I SR spacecraft lacking the solar panels.
In 1978, both spacecraft were upgraded to Block III. The Apollo SR Block III has a slightly larger service module, while the Apollo LR Block III replaces the single, oversized service propulsion engine with a pair of smaller engines derived from the engine on the descent stage of the lunar module; this configuration had first flown on the Manned Venus Flyby mission, but this flight was designated as a Block II flight.
==== Reuseable Command Modules ====
In 1976, NASA announced a program to create reuseable Apollo capsules to drive down costs. The first capsule, Columbia (not to be confused with the Apollo 11 CSM), made its maiden flight in 1981. There are eight capsules in total, with three used with the Apollo SR service module, three used with the Apollo LR service module, and two operated by the Air Force and Department of Defense under the classified Watchtower program. The last expendable Apollo capsule was launched in 1984.
The capsules used with the Apollo SR service module can seat up to five astronauts instead of three, and utilize a Mission Module carried in the S-IVB to provide additional space for the crew, as well as to serve as an adapter for space station docking, as Space Station Freedom, Mir, and the International Space Station all lacked the Apollo drogue-and-chute system still used by the program due to its simplicity compared to the newer APAS system.
Name 	Designation	Type 	Crew Capacity 	First Flight	Status
Columbia 	CM-401 	Lunar 	3 	1981 	In service
Challenger 	CM-402 	Orbital 	5 	1983 	In service
Discovery 	CM-403 	Lunar 	3 	1984 	In service
Atlantis 	CM-404 	Orbital 	5 	1985 	In service
Enterprise 	CM-405 	Lunar 	3 	1987 	In service
Endeavor 	CM-406 	Orbital 	5 	1992 	In service
Mayflower 	CM-407 	Military	Classified (believed to be 5)	1995 	In service
Constitution	CM-408 	Military	Classified (believed to be 5)	2001 	In service
=== Apollo Lunar Module ===
The Apollo Lunar Module (LM) is 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 is designed totally without aerodynamic considerations and was of an extremely lightweight construction. It consists of separate descent and ascent stages, each with its own engine. The descent stage contains storage for the descent propellant, surface stay consumables, and surface exploration equipment. The ascent stage contains 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 more than three days. The contract for design and construction of the lunar module was awarded to Grumman Aircraft Engineering Corporation, and the project was overseen by Thomas J. Kelly. Later variants of the lunar module included the LM Shelter, LM Truck, and LM Shelter Lab (SheLab), as part of the Phase I Lunar Base.
== Launch vehicles ==
Before the Apollo program began, Hermann Oberth 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, Oberth was transferred from the Army to NASA and was made Director of the Marshall Space Flight Center. The initial direct ascent plan to send the three-person Apollo command and 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). 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.
Since Apollo, like Mercury, used more than one launch vehicle for space missions, NASA used spacecraft-launch vehicle combination series numbers: AS-10x for Saturn I, AS-20x for Saturn IC, and AS-50x for Saturn V to designate and plan all missions, rather than numbering them sequentially as in Project Gemini. This was changed by the time human flights began; there was a proposal to number the flights based on the type of CSM they used, but this was quickly rejected (under such a system, Apollo 1 would have been "Apollo S4", while Apollo 11 would have been "Apollo L9").
=== Little Joe II ===
Since Apollo, like Mercury and Gemini, would require a launch escape system (LES) in case of a launch failure, a relatively small rocket was required for qualification flight testing of this system. A rocket bigger than the Little Joe used by Mercury would be required, so the Little Joe II was built by General Dynamics/Convair. After an August 1963 qualification test flight, four LES test flights (A-001 through 004) were made at the White Sands Missile Range between May 1964 and January 1966.
=== Saturn I ===
Saturn I, the first US heavy lift launch vehicle, was initially planned to launch partially equipped CSMs in low Earth orbit tests. The S-I first stage burned RP-1 with liquid oxygen (LOX) oxidizer in eight clustered Rocketdyne H-1 engines, to produce 1,500,000 pounds-force (6,670 kN) of thrust. The S-IV second stage used six liquid hydrogen-fueled Pratt & Whitney RL-10 engines with 90,000 pounds-force (400 kN) of thrust. The S-V third stage flew inactively on Saturn I four times.
The first Saturn I test flight were launched from LC-34, with only the first stage live, 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 (designated AS-101 through AS-105) 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. During this time, the Saturn I (and the Saturn family as a whole) quickly became NASA's standard launcher, quickly relegating the Atlas, Titan, and Delta families to serving the Air Force and National Reconnaissance Office and controlling costs by using common components for their launch vehicles. The payloads typically carried by the Saturn I (such as the OGO and Nimbus satellites, and the Ranger and Surveyor probes) were light enough that the S-IV stage could send them into higher orbits; the lunar missions provided valuable data for development of the S-IVB-500.
In September 1962, NASA planned to launch four crewed CSM flights on the Saturn I from late 1965 through 1966, concurrent with Project Gemini. The 22,500-pound (10,200 kg) payload capacity 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 crewed Earth orbital flights.
The Saturn I ended production in 1971, and the remaining stock of un-uprated S-I stages and S-IV stages was used up by 1977.
=== 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) by uprating the H-1 engine. 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 pounds-force (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 the Apollo SR, a partially fueled Apollo LR, or the LM. 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.
The Saturn IB came in multiple configurations for various launch needs, including the Saturn IB-CE (which added the S-V upper stage), the Saturn IB-B (which replaced the S-IVB with the MS-IVB and the J-2 engine with the HG-3; this configuration never flew due to development on the MG-3 being abandoned early), the Saturn IB-D (which added four UA1205 SRBs; this was the most-common configuration for probes), and the Saturn INT-05A (which completely replaced the S-IB stage with a solid-fueled stage; this variant only launched twice, with the second launch ending in a spectacular explosion when the booster casing was burned through and destroyed the entire stack; the launch was uncrewed).
After the introduction of the Saturn IC in late 1966, the decision was made to abandon plans to use the Saturn IB for crewed flights, and as such, AS-204 (Apollo 1) was moved to a Saturn IC. After production of the Saturn I ended in 1971, the remaining uprated S-IB stages were used up by 1985 (the late retirement date coming due to the fact NASA had ordered 250 S-I stages upon adopting Saturn as its primary launch system); the S-IVB-200 stage is still in production for use with the Saturn IC.
=== Saturn IC ===
Contracted in 1965, the Saturn 1C is the launcher for Orbital Apollo. Its initial purpose was to test the F-1 engine before using it on the Saturn V, before quickly evolving into a full-on replacement for the Saturn IB. The Saturn IC uses the same S-IVB stage built for Apollo's Saturn IB and Saturn V, later upgraded with the new J2-S engine offering improved ISP and thrust in 1974. The Chrysler S-IB first stage of the Saturn IB was replaced with a Boeing-built S-IE stage (the S-ID designation having been used for a Saturn V first stage variant eventually used on the Saturn INT-20.) consisting of a 6.6m monolithic tank structure, with a single F-1 (later F-1A) replacing the original 8 H-1 engines of the Saturn IB. The development and testing of this stage was the key pacing item in the Saturn IC's development. The first unmanned flight took place in 1966 with AS-203, with the first manned flight also being the first manned Apollo flight, Apollo 1, in 1967.
Among the key capabilities of the Saturn 1C was the throttle added to the F-1 as part of F-1A development. While the F-1 (and F-1A) were originally designed with the aim of being used on the Saturn V where late-burn acceleration was controlled by shutting down engines, the F-1A had the ability to throttle to 75%, a capability that was critical in avoiding excessive acceleration later in the S-IE burn on Saturn IC. Saturn IC launch vehicles and flights inherited the AS-200 series number from the Saturn IB starting with AS-203. In addition to launching the Apollo SR, the Saturn IC is also frequently used to launch satellites, both civilian and military.
=== Saturn II ===
There was a large payload gap between the Saturn IB's 46,000-pound (21,000 kg) low Earth orbit capacity and the Saturn V's 310,000-pound (140,000 kg) capability. In the mid-1960s NASA's Marshall Space Flight Center (MSFC) initiated several studies to extend the capabilities of the Saturn family. NASA specified a LEO of 100 nautical miles (185 km), 28° inclination for payload calculations, and the studies examined a number of Modified Launch Vehicle (MLV) configurations based on the Saturn IB and Saturn V launch vehicles as well as Intermediate Payload (INT) launch vehicles based on modified Saturn V stages (MS-IC, MS-II, and MS-IVB). Martin Marietta (builder of Atlas and Titan rockets), Boeing (builder of S-IC first stages), and North American Aviation (builder of the S-II second stage) were three of the companies that provided responses.
North American believed the best way to fill the gap was to use the Saturn V's second stage, the S-II, as the first stage of an intermediate launch vehicle. The basic concept of the Saturn II was to save money by ceasing production of the Saturn IB rocket, and replacing it with launch vehicles built entirely with current Saturn V components. This would allow closing down Chrysler Space Division production lines for the S-IB first stage, and would allow for more efficient integration of rocket systems.
The baseline for the Saturn II was a Saturn V, without the Boeing-built S-IC first stage. The Saturn V's second stage S-II became the first stage, and the non-restartable S-IVB-200 used on the Saturn IB became the second stage. Such a vehicle could not fly without modification, because the S-II was designed to operate in the near-vacuum of high altitude space. Atmospheric thrust suppression reduced the five Rocketdyne J-2 engines' 1,000,000 pounds-force (4,400 kN) of vacuum thrust to 546,500 pounds-force (2,431 kN) at sea level, insufficient to lift the 1,364,900-pound (619,100 kg) weight of the two stages, even without a payload, off of the ground. This required that the S-II be either refit with higher thrust engines, augmented with solid rocket boosters, or both. Another design variable was the amount of the full 1,005,500 pounds (456,100 kg) propellant load carried in the S-II, and 241,300 pounds (109,500 kg) in the S-IVB stage. Eventually, Rocketdyne created a sea-level version of the J-2 that could function on the Saturn II.
To date, the Saturn II has never launched a single crewed flight, but has become a reliable workhorse for not only NASA, but the Air Force and National Reconnaissance Office.
=== Saturn V ===
Saturn V launch vehicles and flights are designated with an AS-500 series number, "AS" indicating "Apollo Saturn" and the "5" indicating Saturn V. The three-stage Saturn V was designed to send a fully fueled CSM and LM to the Moon. It is 33 feet (10.1 m) in diameter and stands 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 burns 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 burn liquid hydrogen; the third stage is a modified version of the S-IVB, with thrust increased to 230,000 pounds-force (1,020 kN) and capability to restart the engine for translunar injection after reaching a parking orbit.
The Saturn V design was found to be highly-adaptable, and innumerable variants have been made over the years. These variants take the form of either alternate configurations of the baseline Saturn V, or radically-different rockets with stretched tankage, solid rocket boosters, and more or alternate engines. Among the better-known variants are the Saturn INT-20 (which omits the S-II stage and is used for launching the Lunar Apollo on Earth orbital missions, as well as probes to Mercury, Venus, and Mars; in the INT-20 configuration, the S-ID stage uses an Atlas-style booster skirt that jettisons the outer four F-1A engines to control acceleration and g-forces) and Saturn INT-21 (which omits the S-IVB stage and was used to launch Skylab, Olympus, and the Space Station Freedom core). Other variants fall under the MLV (Modified Launch Vehicle) series, and are used for a wide variety of applications such as launching larger space station modules for Space Station Freedom and Space Station Discovery, the largest spy satellites such as KH-11, Misty, Lacrosse, Vortex etc, and 99% of all NASA probes and space telescopes.
== Astronauts ==
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 early Apollo crew assignments.
The early 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 Apollo 18. Schmitt participated in the lunar geology training of all of the Apollo landing crews.
Since 1972, all crew assignments have been made by the Chief of the Astronaut Office. All members of subsequent astronaut groups have flown aboard Apollo at least, and many astronauts from Entente Space Council members have also flown aboard Apollo; following the collapse of the German Empire in 1991, German astronauts and Russian cosmonauts have found their way aboard Apollo.
== Development history ==
=== Uncrewed flight tests ===
For a more comprehensive list, see List of Apollo missions.
Two Block I Apollo SRs were launched from LC-34 on suborbital flights in 1966 with the Saturn IB. The first, AS-201 launched on February 26, reached an altitude of 265.7 nautical miles (492.1 km) and splashed down 4,577 nautical miles (8,477 km) downrange in the Atlantic Ocean. The second, AS-202 on August 25, reached 617.1 nautical miles (1,142.9 km) altitude and was recovered 13,900 nautical miles (25,700 km) downrange in the Pacific Ocean. These flights validated the orbital service module engine and the command module heat shield. AS-203 was the first test flight of the Saturn IC, which also launched a Block I Apollo SR.
=== Preparation for crewed flight ===
Two crewed Block II Apollo SR missions were planned: AS-204 and AS-205. The Short-Range 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; starting with the Skylab program, the Short-Range crew position titles were changed to Commander, Pilot, and Flight Engineer. The astronauts would wear a modified version of the Gemini spacesuit.
After an uncrewed LM test flight AS-206, a crew would fly the first Block II Apollo LR and LM in a dual mission known as AS-207/208, or AS-278 (the LM would be launched on a Saturn IC, while the Apollo LR would be launched on the Saturn II; a prior test of the Saturn II would be conducted outside of the Apollo program, designated "Saturn II Test Article No. 1", as had been done for initial testing of the Saturn I and Saturn IB; the Saturn V's first test flight, AS-501, was expected to be with a Block I LR spacecraft). The Long-Range crew positions were titled Commander, Command Module Pilot, and Lunar Module Pilot. The astronauts would begin wearing a new Apollo A6L spacesuit, designed to accommodate lunar extravehicular activity (EVA). 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.
Deke Slayton, the grounded Mercury astronaut who became director of flight crew operations for the Gemini and Apollo programs, selected the first Apollo crew in January 1966, with Grissom as Command Pilot, White as Senior Pilot, and rookie Donn F. Eisele as Pilot. But Eisele dislocated his shoulder twice aboard the KC135 weightlessness training aircraft, and had to undergo surgery on January 27. Slayton replaced him with Chaffee. NASA announced the final crew selection for AS-204 on March 21, 1966, with the backup crew consisting of Gemini veterans James McDivitt and David Scott, with rookie Russell L. "Rusty" Schweickart. Mercury/Gemini veteran Wally Schirra, Eisele, and rookie Walter Cunningham were announced on September 29 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 IC 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.
==== Program delays ====
The spacecraft for the AS-202 and AS-204 missions were delivered by North American Aviation to the Kennedy Space Center 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 crewed 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.
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 uncrewed 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.)
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. Meanwhile, Grumman was also encountering problems with the Lunar Module, eliminating hopes it would be ready for crewed flight in 1967, not long after the first crewed CSM flights.
The issues with AS-204's spacecraft were so bad, that during an uncrewed test in the altitude chamber on December 30, 1966, a fire broke out in the spacecraft. It took technicians fifteen seconds to repressurize the chamber, and an additional four minutes before the complex two-piece plug hatch could be remove, by which point the spacecraft was damaged beyond repair. One technician later stated he witnessed "...a jet of flame, erupting from the side of the capsule like a flamethrower."
With the spacecraft destroyed, AS-204 was cancelled. The Apollo 204 Review Board's final report, issued in April of 1967 after extensive disassembly and inspection of the spacecraft and other Block I spacecraft like it, concluded that the cause of the fire was a combination of damaged wiring, a leaking coolant line, an excess of flammable materials in the capsule, and the pure oxygen atmosphere which the capsule was pressurized with (despite the fact that pure oxygen had not been used during Gemini). The report also concluded that the Block I Apollo Command Module was unfit for spaceflight, and that more changes would need to be implemented for the Block II spacecraft to be considered safe for crewed flight, including a quick-opening hatch, a new cabin atmosphere at launch, and the addition of new insulation on various plumbing and wiring. Revelations about the crew's concerns with the spacecraft, raised with (and dismissed by) Apollo Spacecraft Program Office Manager Joseph Francis Shea in the months preceding the fire, led to Shea's reassignment (and eventual resignation from NASA entirely) and replacement with George Low in April of 1967. Gus Grissom is alleged to have nearly gotten himself fired after a contentious phone call with Shea in the days following the fire, allegedly telling him "We need a man on the Moon before 1970, but a dead man on the Moon won't accomplish a damn thing."
==== Uncrewed Saturn V and LM tests ====
On November 12, 1966, Mueller published an official Apollo mission numbering scheme, using sequential numbers for all flights, crewed or uncrewed. The sequence would start with Apollo 1.
In March 1967, Mueller approved a sequence of mission types which had to be successfully accomplished in order to achieve the crewed 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 uncrewed LM validation using the Saturn IC; B was uncrewed Saturn V validation; C was crewed Apollo LR validation using the Saturn INT-20; D was the first crewed Lunar CSM/LM flight (this replaced AS-258, using a single Saturn V launch); E would be a higher Earth orbit Lunar 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 crewed landing. The list of types covered follow-on lunar exploration to include H lunar landings, I for lunar orbital survey missions, J for extended-stay lunar landings, and K for month-long lunar landings.
The delay in the CSM caused by the fire enabled NASA to catch up on human-rating the LM and Saturn V. AS-204 was remanifested with a Block II Apollo SR (CSM-102), and launched on June 5, 1967 with the same crew, accomplishing a mission designated as the "zero mission", not given a letter designation due to being a holdover from the old testing schedule. Apollo 1's goal, therefore, was to test the Block II Apollo SR for future space station operations, as well as to get a crew inside Apollo to prove that astronauts could operate in the command module. Apollo 2 (AS-205) was the first uncrewed test flight of the LM in Earth orbit, launched from Pad 39A on July 7, 1967. 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 uncrewed test, George Low decided the next LM flight would be crewed. Apollo 3 (AS-301), the first launch of the Block I Lunar Apollo, was launched on September 14, 1967, launched on a Saturn INT-20; this flight was designated as "C-Beta".
Apollo 4 (AS-501) was the first uncrewed flight of the Saturn V, carrying a Block I Apollo LR 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. While the command module survived reentry and the drogue parachutes deployed, the main parachutes failed to, and the command module suffered severe damage upon splashdown. It was determined that such a hard splashdown would be unsurviveable, and so Apollo 4 was deemed a failure.
Apollo 5 launched on January 22, 1968 as a repeat of Apollo 4. This time, the parachutes successfully deployed.
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. 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. 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 crew, canceling a third uncrewed test.
=== Crewed development missions ===
Apollo 7, launched from LC-34 on October 11, 1968, was the C mission, being the first flight of the Block II Apollo LR, launched atop the Saturn INT-20 (due to the Saturn IC not being powerful enough to launch the spacecraft); it was the first crewed Saturn INT-20 launch. In addition to testing the spacecraft in general, the SIM Bay was also tested, carrying numerous scientific instruments (it is alleged that on Flight Day 6, the crew also used cameras in the SIM Bay to carry out a classified spy mission for the Department of Defense). Schirra, Eisele, and Cunningham were the crew on this flight.
Apollo 8 was planned to be the D mission in December 1968, crewed by Cooper, Steadman, and Schweickart, launched on a Saturn V instead of two Saturn ICs. 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 orbit 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 Germans had sent two tortoises, mealworms, wine flies, and other lifeforms around the Moon on September 15, 1968, aboard Sonde 5, and it was believed they might soon repeat the feat with human astronauts. The decision was not announced publicly until successful completion of Apollo 7. Gemini veterans Frank Borman and Jim Lovell, and rookie William Anders captured the world's attention by making ten lunar orbits in 20 hours, transmitting television pictures of the lunar surface on Christmas Eve, and returning safely to Earth.
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 (PLSS) outside the LM. The F mission was successfully carried out on Apollo 10 in May 1969 by Gemini veterans Thomas P. 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, 31 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.
=== Production lunar landings ===
In November 1969, Charles “Pete” Conrad became the third person to step onto the Moon. Conrad and rookie Alan L. Bean made a precision landing of Apollo 12 within walking distance of the Surveyor 3 uncrewed 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.
The initial contracted batch of 15 Saturn Vs was enough for lunar landing missions through Apollo 20. Shortly after Apollo 11, NASA publicized a preliminary list of eight more planned landing sites after Apollo 12, 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 "lifeboat" 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. Apollo was grounded again, for the remainder of 1970 while the oxygen tank was redesigned and an extra one was added (NASA astronauts were not grounded, however, with Roger Chaffee and Vance Brand carrying out the first flight test of the British Arrow, a Gemini-derived spacecraft for future Entente joint space station operations).
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 33 hours and 31 minutes on the surface, and completed two EVAs totalling 9 hours 24 minutes, which was a record for the longest EVA by a lunar crew at the time.
==== Extended missions ====
Apollo 15 was launched on July 26, 1971, with David Scott, Alfred Worden and James Irwin. Scott and Irwin landed on July 30 near Hadley Rille, and spent just under two days, 19 hours on the surface. In over 18 hours of EVA, they collected about 77 kilograms (170 lb) of lunar material.
Apollo 16 landed in the Descartes Highlands on April 20, 1972. The crew was commanded by John Young, with Ken Mattingly and Charles Duke. Young and Duke spent just under three days on the surface, with a total of over 20 hours EVA.
Apollo 17 landed in the Taurus–Littrow region in December 1972. Eugene Cernan commanded Ronald E. Evans and Joe Engle. Cernan and Engle stayed on the surface for just over three days and spent just over 23 hours of total EVA.
Apollo 18 landed in the Marius Hills in February 1973. Richard F. Gordon commanded Vance D. Brand and NASA's first scientist-astronaut, geologist Dr. Harrison H. Schmitt. Gordon and Cernan spent three days on the surface, for 26 hours of total EVA.
Apollo 19 landed in Copernicus Crater in April 1973. Fred Haise, who had been the lunar module pilot on the ill-fated Apollo 13, commanded the crew with Jerry L. Carr and William R. Pogue. During their three-day stay on the lunar surface, Haise and Carr drilled into the wall of Copernicus Crater and discovered volcanic rock.
Apollo 20, the final mission of Phase I of the Apollo program, landed in Tycho Crater in June 1973. Commanded by Mercury veteran Wally Funk, with Jack R. Lousma and Paul J. Weitz, the mission saw Funk (who became the first woman on the Moon) and Lousma land near the Surveyor VII probe.
== Apollo Phase II ==
Initially, it was assumed that Apollo would end sometime in the early 1970s, the main factor being whether or not a New Whig president would be elected. In the 1968 and 1972 elections, however, Robert F. Kennedy, a Progressive, was elected by a landslide (as the Progressives had been since 1940), and made Apollo a national security matter. In 1971, the Germans had finally landed two astronauts on the Moon after Wernher von Braun, unburdened by the oversight of the late Sergei Korolev, nixed Korolev's troublesome N-1 rocket in favor of using the earth orbit rendezvouz mode, by launching the Mondfahrzeug lander on a Proton, then the Union and its crew on the Union rocket, and using the Block D upper stage to send the two spacecraft to the Moon. von Braun's new lander design was much larger than Korolev's, being able to carry two astronauts instead of one, and also being able to dock with the Union instead of the astronaut carrying out a hazardous EVA to transfer between craft. The Mondfahrzeug of Union 13 landed at the Apollo 12 landing site and allegedly stole equipment, which a follow-up visit in 1996 debunked.
Following this, there was widespread public support for keeping Apollo going. Not only was Apollo extended indefinitely, but several related programs were started. First was the Skylab program, aiming to launch the first space station. Germany had beaten the United States in this regard with the Gruß 1 space station, but it was never inhabited after Union 15 failed to dock and Union 16 had to abort during launch, thus making Skylab the first viable space station. Skylab launched on May 14, 1973, between Apollos 19 and 20. This was followed by four missions named Skylabs 1-4 throughout the rest of 1973 and into 1974; all four Skylab missions used the Apollo SR and were launched on the Saturn IC.
Skylab was never meant to be a permanent presence in space, instead being a short-term, proof-of-concept station. The first Autonomous Automated Rendezvous and Docking Vehicle (AARDV, commonly referred to as "Aardvark"), an unmanned variant of the Apollo SR, was launched shortly after Skylab 4 to test space station resupply. After the crew of Skylab 4 left, the AARDV moved to the main docking port and deorbited Skylab. The AARDV also has SR and LR variants, with the LR variant used for the later Space Station Artemis.
Meanwhile, the main Apollo program entered "Phase II" (known as the Apollo Applications Program, or AAP, in the 1960s), broadening its scope from lunar landings to a variety of applications. A clear distinction was made between the two CSM types: Apollo LR flights are designated as Apollo missions, while Orbital CSM flights are designated under whatever the current space station program is (for example, the four flights to Skylab were designated as Skylab flights), though Apollo SR still occasionally flies Apollo-designated missions. Applications Apollo was used for included Earth resources missions for observation (both for NOAA and the military), testing various methods of communication, satellite refurbishment, utilizing a modified lunar module as a lab, and continued lunar operations, including further landings, construction of a rudimentary lunar base, and the launching of a wet workshop space station into lunar orbit after the Germans did the same with the Gruß 7 station (the aforementioned Space Station Artemis). The largest achievement of Phase II, however, was the Manned Venus Flyby, a year-long mission in which an Apollo LR and modified S-IVB made a flyby of Venus.
Into the 1990s, the Apollo program entered "Phase III", and largely became centered around Altair Base, the second-phase lunar base; Space Station Artemis had always been intended for military use, and was sent into a heliocentric orbit after the Kalterkrieg ended with the collapse of the German Empire in 1991; a successor station known as the Lunar Gateway will commence construction in 2025. Further exploration of early Apollo landing sites with new technology was carried out throughout the 1990s, and in the early 2000s, manned exploration of the far side of the Moon commenced.
In 2011, President John Kerry announced plans for a manned Mars landing by 2030. While the Apollo LR spacecraft will be a major part of this undertaking, the program itself is known as Ares; the Apollo program will continue supporting Altair Base and forward development of Ares.
== See also ==
* Skylab program
* Olympus program
* Freedom program
* International Space Station program
* Soyuz programme
* Arrow programme
* Hermes programme
* HOPE programme
* Fuji programme
* Crew Transfer Vehicle
Category:Kaiserreich: Legacy of the Weltkrieg