The Apollo program,also known as Project Apollo,was the 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 from 1968 to 1972. It was first conceived in 1960 during President Dwight D. Eisenhower's administration as a three-person spacecraft to follow the one-person Project Mercury,which put the first Americans 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.
The Apollo Lunar Module,originally designated the Lunar Excursion Module (LEM),was the lunar lander spacecraft that was flown between lunar orbit and the Moon's surface during the United States' Apollo program. It was the first crewed spacecraft to operate exclusively in the airless vacuum of space,and remains the only crewed vehicle to land anywhere beyond Earth.
The Saturn family of American rockets was developed by a team of former German rocket engineers and scientists led by Wernher von Braun to launch heavy payloads to Earth orbit and beyond. The Saturn family used liquid hydrogen as fuel in the upper stages. Originally proposed as a military satellite launcher,they were adopted as the launch vehicles for the Apollo Moon program. Three versions were built and flown:the medium-lift Saturn I,the heavy-lift Saturn IB,and the super heavy-lift Saturn V.
The Apollo spacecraft was composed of three parts designed to accomplish the American Apollo program's goal of landing astronauts on the Moon by the end of the 1960s and returning them safely to Earth. The expendable (single-use) spacecraft consisted of a combined command and service module (CSM) and an Apollo Lunar Module (LM). Two additional components complemented the spacecraft stack for space vehicle assembly:a spacecraft–LM adapter (SLA) designed to shield the LM from the aerodynamic stress of launch and to connect the CSM to the Saturn launch vehicle and a launch escape system (LES) to carry the crew in the command module safely away from the launch vehicle in the event of a launch emergency.
The Saturn IB was an American launch vehicle commissioned by the National Aeronautics and Space Administration (NASA) for the Apollo program. It uprated the Saturn I by replacing the S-IV second stage,with the S-IVB. The S-IB first stage also increased the S-I baseline's thrust from 1,500,000 pounds-force (6,700,000 N) to 1,600,000 pounds-force (7,100,000 N) and propellant load by 3.1%. This increased the Saturn I's low Earth orbit payload capability from 20,000 pounds (9,100 kg) to 46,000 pounds (21,000 kg),enough for early flight tests of a half-fueled Apollo command and service module (CSM) or a fully fueled Apollo Lunar Module (LM),before the larger Saturn V needed for lunar flight was ready.
The Saturn I was a rocket designed as the United States' first medium lift launch vehicle for up to 20,000-pound (9,100 kg) low Earth orbit payloads. The rocket's first stage was built as a cluster of propellant tanks engineered from older rocket tank designs,leading critics to jokingly refer to it as "Cluster's Last Stand". Its development was taken over from the Advanced Research Projects Agency in 1958 by the newly formed civilian NASA. Its design proved sound and flexible. It was successful in initiating the development of liquid hydrogen-fueled rocket propulsion,launching the Pegasus satellites,and flight verification of the Apollo command and service module launch phase aerodynamics. Ten Saturn I rockets were flown before it was replaced by the heavy lift derivative Saturn IB,which used a larger,higher total impulse second stage and an improved guidance and control system. It also led the way to development of the super-heavy lift Saturn V which carried the first men to landings on the Moon in the Apollo program.
Nova was a series of NASA rocket designs that were proposed both before and after the Saturn V rocket used in the Apollo program. Nova was NASA's first large launcher proposed in 1958,for missions similar to what Saturn V was subsequently used for. The Nova and Saturn V designs closely mirrored each other in basic concept,power,size,and function. Differences were minor but practical,and the Saturn was ultimately selected for the Apollo program,largely because it would reuse existing facilities to a greater extent and could make it to the pad somewhat earlier.
The Apollo Applications Program (AAP) was created as early as 1966 by NASA headquarters to develop science-based human spaceflight missions using hardware developed for the Apollo program. AAP was the ultimate development of a number of official and unofficial Apollo follow-on projects studied at various NASA labs. However,the AAP's ambitious initial plans became an early casualty when the Johnson Administration declined to support it adequately,partly in order to implement its Great Society set of domestic programs while remaining within a $100 billion budget. Thus,Fiscal Year 1967 ultimately allocated $80 million to the AAP,compared to NASA's preliminary estimates of $450 million necessary to fund a full-scale AAP program for that year,with over $1 billion being required for FY 1968. The AAP eventually led to Skylab,which absorbed much of what had been developed under Apollo Applications.
The Saturn Vehicle Evaluation Committee,better known as the Silverstein Committee,was a US government commission assembled in 1959 to recommend specific directions that NASA could take with the Saturn rocket program. The committee was chaired by Abe Silverstein,a long-time NASA engineer,with the express intent of selecting upper stages for the Saturn after a disagreement broke out between the Air Force and Army over its development. During the meetings the Committee members outlined a number of different potential designs,including the low-risk solution von Braun was developing with existing ICBM airframes,as well as versions using entirely new upper stages developed to take full advantage of the booster stage. The advantages of using new uppers were so great that the committee won over an initially skeptical von Braun,and the future of the Saturn program changed forever.
Earth orbit rendezvous (EOR) is a method for conducting round trip human flights to the Moon,involving the use of space rendezvous to assemble,and possibly fuel,components of a translunar vehicle in low Earth orbit. It was considered and ultimately rejected in favor of lunar orbit rendezvous (LOR) for NASA's Apollo program of the 1960s and 1970s,mainly because LOR does not require a spacecraft big enough to both make the return trip from Earth orbit to splashdown in the ocean,and a soft landing on the lunar surface. Three decades later,it was planned to be used for Project Constellation,until that program's cancellation in October 2010.
Direct ascent is a method of landing a spacecraft on the Moon or another planetary surface directly,without first assembling the vehicle in Earth orbit,or carrying a separate landing vehicle into orbit around the target body. It was proposed as the first method to achieve a crewed lunar landing in the United States Apollo program,but was rejected because it would have required developing a prohibitively large launch vehicle.
Lunar orbit rendezvous (LOR) is a process for landing humans on the Moon and returning them to Earth. It was utilized for the Apollo program missions in the 1960s and 1970s. In a LOR mission,a main spacecraft and a smaller lunar lander travel to lunar orbit. The lunar lander then independently descends to the surface of the Moon,while the main spacecraft remains in lunar orbit. After completion of the mission there,the lander returns to lunar orbit to rendezvous and re-dock with the main spacecraft,then is discarded after transfer of crew and payload. Only the main spacecraft returns to Earth.
The Exploration Systems Architecture Study (ESAS) is the official title of a large-scale,system level study released by the National Aeronautics and Space Administration (NASA) in November 2005 of his goal of returning astronauts to the Moon and eventually Mars—known as the Vision for Space Exploration. The Constellation Program was cancelled in 2010 by the Obama Administration and replaced with the Space Launch System,later renamed as the Artemis Program in 2017 under the Trump Administration.
The Ares V was the planned cargo launch component of the cancelled NASA Constellation program,which was to have replaced the Space Shuttle after its retirement in 2011. Ares V was also planned to carry supplies for a human presence on Mars. Ares V and the smaller Ares I were named after Ares,the Greek god of war.
The Saturn C-2 was the second rocket in the Saturn C series studied from 1959 to 1962. The design was for a four-stage launch vehicle that could launch 21,500 kg (47,300 lb) to low Earth orbit and send 6,800 kg (14,900 lb) to the Moon via Trans-Lunar Injection.
The C-2 design concept was for a proposed crewed circumlunar flight and the Earth orbit rendezvous (EOR) missions. It was initially considered for the Apollo lunar landing at the earliest possible date (1967).
The Saturn C-4 was the fourth rocket in the Saturn C series studied from 1959 to 1962. The C-4 design was proposed in 1960 for a three-stage launch vehicle that could launch 99,000 kg (218,000 lb) to low Earth orbit and send 32,000 kg (70,000 lb) to the Moon via trans-lunar injection. It met the initial requirements for a lunar orbit rendezvous and lunar landing mission.
The Saturn C-3 was the third rocket in the Saturn C series studied from 1959 to 1962. The design was for a three-stage launch vehicle that could launch 45,000 kilograms (99,000 lb) to low Earth orbit and send 18,000 kilograms (40,000 lb) to the Moon via trans-lunar injection.
Saturn V is a retired American super heavy-lift launch vehicle developed by NASA under the Apollo program for human exploration of the Moon. The rocket was human-rated,had three stages,and was powered with liquid fuel. Flown from 1967 to 1973,it was used for nine crewed flights to the Moon,and to launch Skylab,the first American space station.
Advanced Gemini is a number of proposals that would have extended the Gemini program by the addition of various missions,including crewed low Earth orbit,circumlunar and lunar landing missions. Gemini was the second crewed spaceflight program operated by NASA,and consisted of a two-seat spacecraft capable of maneuvering in orbit,docking with uncrewed spacecraft such as Agena Target Vehicles,and allowing the crew to perform tethered extra-vehicular activities.
DIRECT was a late-2000s proposed alternative super heavy lift launch vehicle architecture supporting NASA's Vision for Space Exploration that would replace the space agency's planned Ares I and Ares V rockets with a family of Shuttle-Derived Launch Vehicles named "Jupiter". It was intended to be the alternative to the Ares I and Ares V rockets which were under development for the Constellation program,intended to develop the Orion spacecraft for use in Earth orbit,the Moon,and Mars.
