The Saturn V (pronounced "Saturn Five") was a multistage liquid-fuel expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. In total NASA launched thirteen Saturn V rockets with no loss of payload. It remains the largest and most powerful launch vehicle ever brought to operational status from a height, weight and payload standpoint. The Soviet Energia, which flew two test missions in the late 1980s before being canceled, had slightly more takeoff thrust.

The largest production model of the Saturn family of rockets, the Saturn V was designed under the direction of Wernher von Braun at the Marshall Space Flight Center in Huntsville, Alabama, with Boeing, North American Aviation, Douglas Aircraft Company, and IBM as the lead contractors. Von Braun's design was based in part on his work on the "Aggregate" series of rockets, especially the A-10, A-11, and A12 in Germany during World War II. The three stages of the Saturn V were developed by various NASA contractors, but following a sequence of mergers and takeovers all of them are now owned by Boeing.

Background

In 1957, the Soviet Union launched Sputnik 1, the first artificial satellite. Lyndon B. Johnson—at the time Senate Majority Leader and later President—recalled feeling "the profound shock of realizing that it might be possible for another nation to achieve technological superiority over this great country of ours." The resulting Sputnik crisis continued, and by 1961, when Soviet cosmonaut Yuri Gagarin orbited the Earth aboard Vostok 1 during the first human spaceflight, many people in the United States felt the Soviets had developed a considerable lead in the Space Race.

On May 25, 1961, President Kennedy announced that America would attempt to land a man on the Moon by the end of the decade. At that time, the only experience the United States had with human spaceflight was the 15-minute suborbital flight of Alan Shepard aboard Freedom 7. No rocket then available was capable of propelling a manned spacecraft to the Moon in one piece. The Saturn I was in development, but would not fly for six months. Although larger than other contemporary rockets, it would require several launches to place all the components of a lunar spacecraft in orbit. The much larger Saturn V had not been designed, although its powerful F-1 engine had already been developed and test fired.

Mission configuration

Early in the planning process, NASA considered three leading ideas for the moon mission: Earth Orbit Rendezvous, Direct Ascent, and Lunar Orbit Rendezvous (LOR). A direct ascent configuration would launch a larger rocket which would land directly on the lunar surface, while an Earth orbit rendezvous would launch two smaller spacecraft which would combine in Earth orbit. A LOR mission would involve a single rocket launching a single spacecraft, but only a small part of that spacecraft would land on the moon. That smaller landing module would then rendezvous with the main spacecraft, and the crew would return home.

NASA at first dismissed LOR as a riskier option, given that an orbital rendezvous had yet to be performed in Earth orbit, much less in lunar orbit. Several NASA officials, including Langley Research Center engineer John Houbolt and NASA Administrator George Low, argued that a Lunar Orbit Rendezvous provided the simplest landing on the moon, the most cost–efficient launch vehicle and, perhaps most importantly, the best chance to accomplish a lunar landing within the decade. Other NASA officials were convinced, and LOR was officially selected as the mission configuration for the Apollo program on 7 November 1962.

Development

C-1 to C-4

Between 1960 and 1962, the Marshall Space Flight Center (MSFC) designed rockets that could be used for various missions.

The C-1 was developed into the Saturn I, and the C-2 rocket was dropped early in the design process in favor of the C-3, which was intended to use two F-1 engines on its first stage, four J-2 engines for its second stage, and an S-IV stage, using six RL-10 engines.

NASA planned to use the C-3 as part of the Earth Orbit Rendezvous concept, with at least four or five launches needed for a single mission, but MSFC was already planning an even bigger rocket, the C-4, which would use four F-1 engines on its first stage, an enlarged C-3 second stage, and the S-IVB, a stage with a single J-2 engine, as its third stage. The C-4 would need only two launches to carry out an Earth Orbit Rendezvous mission.

C-5

On January 10, 1962, NASA announced plans to build the C-5. The three-stage rocket would consist of five F-1 engines for the first stage, five J-2 engines for the second stage, and a single, additional J-2 engine for the third stage. The C-5 was designed for the higher payload capacity necessary for a lunar mission, and could carry up to 41,000 kg into lunar orbit.

The C-5 would undergo component testing even before the first model was constructed. The rocket's third stage would be utilized as the second stage for the C-IB, which would serve both to demonstrate proof of concept and feasibility for the C-5, but would also provide flight data critical to the continued development of the C-5. Rather than undergoing testing for each major component, the C-5 would be tested in an "all-up" fashion, meaning that the first test flight of the rocket would include complete versions of all three stages. By testing all components at once, far fewer test flights would be required before a manned launch.

The C-5 was confirmed as NASA's choice for the Apollo Program in early 1963, and was given a new name—the Saturn V.

Technology

The Saturn V's huge size and payload capacity dwarfed all other previous rockets which had successfully flown at that time. With the Apollo spacecraft on top it stood tall and without fins it was 33 feet (10 m) in diameter. Fully fueled it had a total mass of 6.5 million pounds (3,000 tonnes) and a payload capacity of 260,000 pounds (118,000 kg) to LEO. Comparatively, at , the Saturn V is just one foot shorter than St Paul's Cathedral in London, and only cleared the doors of the Vehicle Assembly Building (VAB) by 6 ft (1.82 m) when rolled out. In contrast, the Redstone used on Freedom 7, the first manned American spaceflight, was just under longer than the S-IVB stage, and less powerful than the Launch Escape System rockets mounted on the Apollo command module.

Saturn V was principally designed by the Marshall Space Flight Center in Huntsville, Alabama, although numerous major systems, including propulsion, were designed by subcontractors. It used the powerful new F-1 and J-2 rocket engines for propulsion. When tested, these engines shattered the windows of nearby houses. Designers decided early on to attempt to use as much technology from the Saturn I program as possible. Consequently, the S-IVB third stage of the Saturn V was based on the S-IV second stage of the Saturn I. The instrument unit that controlled the Saturn V shared characteristics with that carried by the Saturn I.

Stages

The Saturn V consisted of three stages– the S-IC first stage, S-II second stage and the S-IVB third stage– and the instrument unit. All three stages used liquid oxygen (LOX) as an oxidizer. The first stage used RP-1 for fuel, while the second and third stages used liquid hydrogen (LH2). The upper stages also used small solid-fueled ullage motors that helped to separate the stages during the launch, and to ensure that the liquid propellants were in a proper position to be drawn into the pumps.

S-IC first stage

The S-IC was built by The Boeing Company at the Michoud Assembly Facility, New Orleans, where the Space Shuttle External Tanks are now built. Most of its mass of over two thousand metric tonnes at launch was propellant, in this case RP-1 rocket fuel and liquid oxygen oxidizer. It was 138 feet (42 m) tall and 33 feet (10 m) in diameter, and provided over 34 MN (7.64 million pounds force) of thrust to get the rocket through the first 61 kilometers of ascent. The S-IC stage had a dry weight of about 288,000 pounds (131,000 kg) and fully fueled at launch had a total weight of 5.0 million pounds (2.3 million kg). The five F-1 engines were arranged in a cross pattern. The center engine was fixed, while the four outer engines could be hydraulically turned to control the rocket. In flight, the center engine was turned off about 26 seconds earlier than the outboard engines to limit acceleration. During launch, the S-IC fired its engines for 168 seconds (ignition occurred about 7 seconds before liftoff) and at engine cutoff, the vehicle was at an altitude of about 42 miles (68 km), was downrange about 58 miles (93 km), and was moving about 7,850 ft/sec (2,390 m/sec, or approximately 5,352 mph).

S-II second stage

The S-II was built by North American Aviation at Seal Beach, California. Using liquid hydrogen and liquid oxygen, it had five J-2 engines in a similar arrangement to the S-IC, also using the outer engines for control. The S-II was 81 feet and 7 inches (24.9 m) tall with a diameter of 33 feet (10 m), identical to the S-IC, and thus is the largest cryogenic stage ever built. The S-II had a dry weight of about 80,000 pounds (36,000 kg) and fully fueled, weighed 1.06 million pounds (480,000 kg). The second stage accelerated the Saturn V through the upper atmosphere with 5.1 MN of thrust (in vacuum). When loaded, significantly more than 90 percent of the mass of the stage was propellant; however, the ultra-lightweight design had led to two failures in structural testing. Instead of having an intertank structure to separate the two fuel tanks as was done in the S-IC, the S-II used a common bulkhead that was constructed from both the top of the LOX tank and bottom of the LH2 tank. It consisted of two aluminum sheets separated by a honeycomb structure made of phenolic resin. This bulkhead had to insulate against the 70 °C (125 °F) temperature difference between the two tanks. The use of a common bulkhead saved 3.6 metric tons in weight. Like the S-IC, the S-II was transported by sea.

S-IVB third stage

The S-IVB was built by the Douglas Aircraft Company at Huntington Beach, California. It had one J-2 engine and used the same fuel as the S-II. The S-IVB used a common bulkhead to insulate the two tanks. It was 58 feet and 7 inches (17.85 m) tall with a diameter of 21 feet and 8 inches (6.60 m) and was also designed with high mass efficiency, though not quite as aggressively as the S-II. The S-IVB had a dry weight of about 25,000 pounds (11,000 kg) and fully fueled, weighed about 262,000 pounds (119,000 kg). This stage was used twice during the mission: first in a 2.5 min burn for the orbit insertion after second stage cutoff, and later for the trans lunar injection (TLI) burn, lasting about 6 mins. Two liquid-fueled auxiliary propulsion system units mounted at the aft end of the stage were used for attitude control during the parking orbit and the trans-lunar phases of the mission. The two APSs were also used as ullage engines to help settle the fuel prior to the translunar injection burn.

The S-IVB was the only rocket stage of the Saturn V small enough to be transported by plane, in this case the Guppy. Apart from the interstage adapter and the stage restart capability, this stage is nearly identical to the second stage of the Saturn IB rocket.

Instrument unit

Instrument Unit was built by IBM and rode atop the third stage. It was constructed at the Space Systems Center in Huntsville. This computer controlled the operations of the rocket from just before liftoff until the S-IVB was discarded. It included guidance and telemetry systems for the rocket. By measuring the acceleration and vehicle attitude, it could calculate the position and velocity of the rocket and correct for any deviations.

Range safety

In the event of an abort requiring the destruction of the rocket, the range safety officer would remotely shut down the engines and after several seconds send another command for the shaped explosive charges attached to the outer surfaces of the rocket to detonate. These would make cuts in fuel and oxidizer tanks to disperse the fuel quickly and to minimize mixing. The pause between these actions would give time for the crew to escape using the Launch Escape Tower or (in the later stages of the flight) the propulsion system of the Service module. A third command, "safe", was used after the S-IVB stage reached orbit to irreversibly deactivate the self-destruct system. The system was also inactive as long as the rocket was still on the launch pad.

Comparisons

The Soviet counterpart of the Saturn V was the N-1 rocket. The Saturn V was taller, heavier and had greater payload capacity, but the N-1 had more liftoff thrust and a larger first stage diameter. The N1 had four test launches, each resulting in the vehicle catastrophically failing early in the flight, before the program was canceled. The first stage of Saturn V used five powerful engines rather than the 30 smaller engines of the N-1. During two launches, Apollo 6 and Apollo 13, the Saturn V was able to recover from engine loss incidents. The N-1 likewise was designed to compensate for engine failures, but the system never successfully saved a launch from failure.

The three-stage Saturn V had a peak thrust of at least 34.02 MN (SA-510 and subsequent) and a lift capacity of 118,000 kg to LEO. The SA-510 mission (Apollo 15) had a liftoff thrust of 7.823 million pounds (34.8 MN). The SA-513 mission (Skylab) had slightly greater liftoff thrust of 7.891 million pounds (35.1 MN). No other operational launch vehicle has ever surpassed the Saturn V in height, weight, or payload. If the two Soviet Energia test launches are counted as operational, it had the same liftoff thrust as SA-513, 35.1 MN. The N-1 had a sea-level liftoff thrust of about 9.9 million pounds (44.1 MN), but it never achieved orbit.

Hypothetical future versions of the Soviet Energia might have been significantly more powerful than the Saturn V, delivering 46 MN of thrust and able to deliver up to 175 metric tonnes to LEO in the "Vulkan" configuration. Planned uprated versions of the Saturn V using F-1A engines would have had about 18 percent more thrust and 137,250 kg (302,580 lb) payload. NASA contemplated building larger members of the Saturn family, such as the Saturn C-8, and also unrelated rockets, such as Nova, but these were never produced.

The Space Shuttle generates a peak thrust of 30.1 MN, and payload capacity to LEO (excl. Shuttle Orbiter itself) is 28,800 kg, which is about 25 percent of the Saturn V's payload. If the Shuttle Orbiter itself is counted as payload, this would be about 112,000 kg (248,000 lb). An equivalent comparison would be the Saturn V S-IVB third stage total orbital mass on Apollo 15, which was 140,976 kg (310,800 lb).

Some other recent launch vehicles have a small fraction of the Saturn V's payload capacity: the European Ariane 5 with the newest versions Ariane 5 ECA delivers up to 10,000 kg to geostationary transfer orbit (GTO). The US Delta 4 Heavy, which launched a dummy satellite on December 21, 2004, has a capacity of 13,100 kg to geosynchronous transfer orbit. The Atlas V (using engines based on a Russian design) delivers up to 25,000 kg to LEO and 13,605 kg to GTO.

S-IC thrust comparisons

Because of its large size, attention is often focused on the S-IC thrust and how this compares to other large rockets. However, several factors make such comparisons more complex than first appears:

• Commonly-referenced thrust numbers are a specification, not an actual measurement. Individual stages and engines may fall short or exceed the specification, sometimes significantly.
• The F-1 thrust specification was uprated beginning with Apollo 15 (SA-510) from 1.5 million lbf (6.67 MN) to 1.522 million lbf (6.77 MN), or 7.61 million lbf (33.85 MN) for the S-IC stage. The higher thrust was achieved via a redesign of the injector orifices and a slightly higher propellant mass flow rate. However, comparing the specified number to the actual measured thrust of 7.823 million lbf (34.8 MN) on Apollo 15 shows a significant difference.
• There is no "bathroom scale" way to directly measure thrust of a rocket in flight. Rather a mathematical calculation is made from combustion chamber pressure, turbopump speed, calculated propellant density and flow rate, nozzle design, and atmospheric conditions, in particular, external pressure.
• Thrust varies greatly with external pressure and thus, with altitude, even for a non-throttled engine. For example on Apollo 15, the calculated total liftoff thrust (based on actual measurements) was about 7.823 million lbf (34.8 MN), which increased to 9.18 million lbf (40.8 MN) at T+135 seconds, just before center engine cutoff (CECO), at which time the jet was heavily underexpanded.
• Thrust specifications are often given as vacuum thrust (for upper stages) or sea level thrust (for lower stages or boosters), sometimes without qualifying which one. This can lead to incorrect comparisons.
• Thrust specifications are often given as average thrust or peak thrust, sometimes without qualifying which one. Even for a non-throttled engine at a fixed altitude, thrust can often vary somewhat over the firing period due to several factors. These include intentional or unintentional mixture ratio changes, slight propellant density changes over the firing period, and variations in turbopump, nozzle and injector performance over the firing period.

Without knowing the exact measurement technique and mathematical method used to determine thrust for each different rocket, comparisons are often inexact. As the above shows, the specified thrust often differs significantly from actual flight thrust calculated from direct measurements. The thrust stated in various references is often not adequately qualified as to vacuum vs sea level, or peak vs average thrust.

Similarly, payload increases are often achieved in later missions independent of engine thrust. This is by weight reduction or trajectory reshaping.

The result is there is no single absolute figure for engine thrust, stage thrust or vehicle payload. There are specified values and actual flight values, and various ways of measuring and deriving those actual flight values.

The performance of each Saturn V launch was extensively analyzed and a Launch Evaluation Report produced for each mission, including a thrust/time graph for each vehicle stage on each mission.

Assembly

After the construction and ground testing of a stage was completed, it was then shipped to the Kennedy Space Center. The first two stages were so large that the only way to transport them was by barge. The S-IC, constructed in New Orleans, was transported down the Mississippi River to the Gulf of Mexico. After rounding Florida, it was then transported up the Intra-Coastal Waterway to the Vertical Assembly Building (now called the Vehicle Assembly Building). This is in essence the same route used by NASA today to ship Space Shuttle External Tanks. The S-II was constructed in California and so traveled via the Panama Canal. The third stage and Instrument Unit could be carried by the Aero Spacelines Pregnant Guppy and Super Guppy, but may also be carried by barge if warranted.

On arrival at the Vertical Assembly Building, each stage was checked out in a horizontal position before being moved to a vertical position. NASA also constructed large spool-shaped structures that could be used in place of stages if a particular stage was late. These spools had the same height and mass and contained the same electrical connections as the actual stages.

NASA assembled the Saturn V on a Mobile Launcher Platform (MLP), which consisted of a Launch Umbilical Tower (LUT) with nine swing arms (including the crew access arm), a "hammerhead" crane, and a water suppression system which was activated prior to launch. After assembly was completed, the entire stack was moved from the VAB to the launch complex using the Crawler Transporter (CT). Built by the Marion Power Shovel Company, and still in use today for transporting the smaller and lighter Space Shuttle, the CT runs on four double tracked treads, each with 57 'shoes'. Each shoe weighs 900 kg (2,000 lb). This transporter was required to keep the rocket level as it traveled the 3 miles (5 km) to the launch site, especially at the 3% grade encountered at the launch site itself. the CT also carried the Moveable Support Tower (MST), which allowed technicians access to the rocket until 8 hours before launch, when it was moved to the "halfway" point on the Crawlerway (the junction between the VAB and the two launch pads).

Lunar mission launch sequence

The Saturn V carried all Apollo lunar missions. All Saturn V missions launched from Launch Complex 39 at the John F. Kennedy Space Center. After the rocket cleared the launch tower, mission control transferred to the Johnson Space Center in Houston, Texas.

An average mission used the rocket for a total of just 20 minutes. Although Apollo 6 and Apollo 13 experienced engine failures, the onboard computers were able to compensate by burning the remaining engines longer, and none of the Apollo launches resulted in a payload loss.

S-IC sequence

The first stage burned for 2.5 minutes, lifting the rocket to an altitude of and a speed of and burning of propellant.

At 8.9 seconds before launch, the first stage ignition sequence started. The center engine ignited first, followed by opposing outboard pairs at 300-millisecond intervals to reduce the structural loads on the rocket. When thrust had been confirmed by the onboard computers, the rocket was "soft-released" in two stages: first, the hold-down arms released the rocket, and second, as the rocket began to accelerate upwards, it was slowed by tapered metal pins pulled through dies for half a second. Once the rocket had lifted off, it could not safely settle back down onto the pad if the engines failed.

It took about 12 seconds for the rocket to clear the tower. During this time, it yawed 1.25 degrees away from the tower to ensure adequate clearance despite adverse winds. (This yaw, although small, can be seen in launch photos taken from the east or west.) At an altitude of the rocket rolled to the correct flight azimuth and then gradually pitched down until 38 seconds after second stage ignition. This pitch program was set according to the prevailing winds during the launch month. The four outboard engines also tilted toward the outside so that in the event of a premature outboard engine shutdown the remaining engines would thrust through the rocket's center of gravity. The Saturn V quickly accelerated, reaching at over in altitude. Much of the early portion of the flight was spent gaining altitude, with the required velocity coming later.

At about 80 seconds, the rocket experienced maximum dynamic pressure (Max Q). The dynamic pressure on a rocket varies with air density and the square of relative velocity. Although velocity continues to increase, air density decreases so quickly with altitude that dynamic pressure falls below Max Q.

Acceleration increased during S-IC flight for two reasons: decreasing propellant mass; and increasing thrust as F-1 engine efficiency improved in the thinner air at altitude. At 135 seconds, the inboard (center) engine shut down to limit acceleration to 4 g. The other engines continued to burn until either oxidizer or fuel depletion as detected by sensors in the suction assemblies. First stage separation was a little less than one second after cutoff to allow for F-1 thrust tail-off. Eight small solid fuel separation motors backed the S-IC from the interstage at an altitude of about . The first stage continued ballistically to an altitude of about and then fell in the Atlantic Ocean about downrange.

S-II sequence

After S-IC separation, the S-II second stage burned for 6 minutes and propelled the craft to 109 miles (176 km) and 15,647 mph (25,182 km/h– 7.00 km/s), close to orbital velocity.

For the first two unmanned launches, eight solid-fuel ullage motors ignited for four seconds to give positive acceleration to the S-II stage, followed by start of the five J-2 engines. For the first seven manned Apollo missions only four ullage motors were used on the S-II, and they were eliminated completely for the final four launches. About 30 seconds after first stage separation, the interstage ring dropped from the second stage. This was done with an inertially fixed attitude so that the interstage, only 1 meter from the outboard J-2 engines, would fall cleanly without contacting them. Shortly after interstage separation the Launch Escape System was also jettisoned. See Apollo abort modes for more information about the various abort modes that could have been used during a launch.

About 38 seconds after the second stage ignition the Saturn V switched from a preprogrammed trajectory to a "closed loop" or Iterative Guidance Mode. The Instrument Unit now computed in real time the most fuel-efficient trajectory toward its target orbit. If the Instrument Unit failed, the crew could switch control of the Saturn to the Command Module's computer, take manual control, or abort the flight.

About 90 seconds before the second stage cutoff, the center engine shut down to reduce longitudinal pogo oscillations. A pogo suppressor, first flown on Apollo 14, stopped this motion but the center engine was still shut down early to limit acceleration G forces. At around this time, the LOX flow rate decreased, changing the mix ratio of the two propellants, ensuring that there would be as little propellant as possible left in the tanks at the end of second stage flight. This was done at a predetermined delta-v.

Five level sensors in the bottom of each S-II propellant tank were armed during S-II flight, allowing any two to trigger S-II cutoff and staging when they were uncovered. One second after the second stage cut off it separated and several seconds later the third stage ignited. Solid fuel retro-rockets mounted on the interstage at the top of the S-II fired to back it away from the S-IVB. The S-II impacted about 4200 km (2,300 miles) from the launch site.

S-IVB sequence

Unlike the two-phase separation of the S-IC and S-II, the S-II and S-IVB stages separated with a single step. Although it was constructed as part of the third stage, the interstage remained attached to the second stage.

During Apollo 11, a typical lunar mission, the third stage burned for about 2.5 minutes until first cutoff at 11 minutes 40 seconds. At this point it was 2640 km downrange and in a parking orbit at an altitude of 188 km and velocity of 7790 m/sec. The third stage remained attached to the spacecraft while it orbited the Earth two and a half times while astronauts and mission controllers prepared for translunar injection (TLI).



This parking orbit is quite low by Earth orbit standards, and it would have been short-lived due to aerodynamic drag. This was not a problem on a lunar mission because of the short stay in the parking orbit. The S-IVB also continued to thrust at a low level with hydrogen vents to settle the propellants in their tanks, and this thrust easily exceeded aerodynamic drag.

For the final three Apollo flights, the temporary parking orbit was even lower (approximately ), to increase payload for these missions. For the two Earth orbit missions of the Saturn V, Apollo 9 and Skylab, the orbits were much higher and more typical of manned orbital missions.

On Apollo 11, TLI came at 2 hours and 44 minutes after launch. The S-IVB burned for almost six minutes giving the spacecraft a velocity close to the Earth's escape velocity of 11.2 km/s (40,320 km/h; 25,053 mph). This gave an energy-efficient transfer to lunar orbit with the moon helping to capture the spacecraft with a minimum of CSM fuel consumption.

About 40 minutes after TLI the Apollo Command Service Module (CSM) separated from the third stage, turned 180 degrees and docked with the Lunar Module (LM) that rode below the CSM during launch. The CSM and LM separated from the spent third stage 50 minutes later.

If it were to remain on the same trajectory as the spacecraft, the S-IVB could have presented a collision hazard so its remaining propellants were vented and the auxiliary propulsion system fired to move it away. For lunar missions before Apollo 13, the S-IVB was directed toward the moon's trailing edge in its orbit so that the moon would slingshot it beyond earth escape velocity and into solar orbit. From Apollo 13 onwards, controllers directed the S-IVB to hit the Moon. Seismometers left behind by previous missions detected the impacts, and the information helped map the inside of the Moon.

Apollo 9 was a special case; although it was an earth orbital mission, after spacecraft separation its S-IVB was fired out of earth orbit into a solar orbit.

On September 3, 2002, Bill Yeung discovered a suspected asteroid, which was given the discovery designation J002E3. It appeared to be in orbit around the Earth, and was soon discovered from spectral analysis to be covered in white titanium dioxide paint, the same paint used for the Saturn V. Calculation of orbital parameters identified the apparent asteroid as being the Apollo 12 S-IVB stage. Mission controllers had planned to send Apollo 12's S-IVB into solar orbit, but the burn after separating from the Apollo spacecraft lasted too long, and hence it did not pass close enough to the Moon, remaining in a barely-stable orbit around the Earth and Moon. In 1971, through a series of gravitational perturbations, it is believed to have entered in a solar orbit and then returned into weakly-captured Earth orbit 31 years later. It left Earth orbit again in June 2003. Another near-earth object, discovered in 2006 and designated 6Q0B44E, may also be part of an Apollo spacecraft.

Skylab

In 1968, the Apollo Applications Program was created to look into science missions that could be performed with the surplus Apollo hardware. Much of the planning centered on the idea of a space station, which eventually spawned the Skylab program. Skylab was launched using a two-stage Saturn V, sometimes called a Saturn INT-21. It was the only launch not directly related to the Apollo lunar landing program.

Originally it was planned to use a 'wet workshop' concept, with a rocket stage being launched into orbit by a Saturn 1B and its spent S-IVB outfitted in space, but this was abandoned for the 'dry workshop' concept: An S-IVB stage from a Saturn IB was converted into a space station on the ground and launched on a Saturn V. A backup, constructed from a Saturn V third stage, is now on display at the National Air and Space Museum.

Three crews lived aboard Skylab from May 25, 1973 to February 8, 1974, with Skylab remaining in orbit until July 11, 1979.

Proposed post-Apollo developments

The (canceled) second production run of Saturn Vs would very likely have used the F-1A engine in its first stage, providing a substantial performance boost. Other likely changes would have been the removal of the fins (which turned out to provide little benefit when compared to their weight); a stretched S-IC first stage to support the more powerful F-1As; and uprated J-2s for the upper stages.

A number of alternate Saturn vehicles were proposed based on the Saturn V, ranging from the Saturn INT-20 with an S-IVB stage and interstage mounted directly onto an S-IC stage, through to the Saturn V-23 which would not only have five F-1 engines in the first stage, but also four strap-on boosters with two F-1 engines each: giving a total of thirteen F-1 engines firing at launch.

The Space Shuttle was initially conceived of as a cargo transport to be used in concert with the Saturn V, even to the point that a "Saturn-Shuttle," using the current orbiter and external tank, but with the tank mounted on a modified, fly-back version of the S-IC, would be used to power the Shuttle during the first two minutes of flight, after which the S-IC would be jettisoned (which would then fly back to KSC for refurbishment) and the Space Shuttle Main Engines would then fire and place the orbiter into orbit. The Shuttle would handle space station logistics, while Saturn V would launch components. Lack of a second Saturn V production run killed this plan and has left the United States without a heavy-lift booster. Some in the U.S. space community have come to lament this situation, as continued production would have allowed the International Space Station, using a Skylab or Mir configuration with both U.S. and Russian docking ports, to have been lifted with just a handful of launches, with the "Saturn Shuttle" concept possibly eliminating the conditions that caused the Challenger Disaster in 1986.

The Saturn V would have been the prime launch vehicle for the canceled Voyager Mars probes, and was to have been the launch vehicle for the nuclear rocket stage RIFT test program and the later NERVA.

Successors

U.S. proposals for a rocket larger than the Saturn V from the late 1950s through the early 1980s were generally called Nova. Over thirty different large rocket proposals carried the Nova name.

Wernher von Braun and others also had plans for a rocket that would have featured eight F-1 engines in its first stage allowing it to launch a manned spacecraft on a direct ascent flight to the Moon. Other plans for the Saturn V called for using a Centaur as an upper stage or adding strap-on boosters. These enhancements would have increased its ability to send large unmanned spacecraft to the outer planets or manned spacecraft to Mars.

In 2006, NASA, as part of the upcoming Constellation Program that would replace the Space Shuttle after 2010, unveiled plans to construct the heavy-lift Ares V rocket, a Shuttle Derived Launch Vehicle using some existing Space Shuttle and Saturn V infrastructure. Named in homage of the Saturn V, the original design, based on the Space Shuttle External Tank, was . tall, and powered by five Space Shuttle Main Engines (SSMEs) and two uprated five-segment Space Shuttle Solid Rocket Boosters, which a modified variation would be used for the crew-launched Ares I rocket. As the designed evolved, the Ares V was slightly modified, with the same diameter as that of the Saturn V's S-IC and S-II stages, and in place of the five SSMEs, five RS-68 rocket engines, the same engines used on the Delta IV EELV, would be used. The switch from the SSME to the RS-68 was due to the steep price of the cost of the SSME, as that it would be thrown away along with the Ares V core stage after each use, while the RS-68 engine, which is expendable, is cheaper, simpler to manufacture, and more powerful than the SSME. In 2008, NASA again redesigned the Ares V, lengthening and widening the core stage and added an extra RS-68 engine, giving the launch vehicle a total of six engines. The six RS-68B engines, during launch, will be augmented by two "5.5-segment" SRBs instead of the original five-segment designs, although no decision has yet been made on the number of segments NASA would be using on the final design. If the six RS-68B/5.5-segment SRB variant is used, the vehicle would have a total of approx. . of thrust at liftoff, making it more powerful than the Saturn V or the Soviet/Russian N-1 and Energia boosters. An upper stage, known as the Earth Departure Stage and based on the S-IVB, will utilize a more advanced version of the J-2 engine known as the "J-2X," and will place the Altair lunar landing vehicle into a low earth orbit. At . tall and with the capability of placing ~180 tons into low earth orbit, the Ares V will surpass the Saturn V and the two Soviet/Russian superboosters in both height, lift, and launch capability.

The RS-68B engines, based on the current RS-68 and RS-68A engines built by the Rocketdyne Division of Pratt and Whitney (formerly under the ownerships of Boeing and Rockwell International), produce less than half the thrust per engine as the Saturn V's F-1 engines, but are more efficient and can be throttled up or down, much like the SSMEs on the Shuttle. The J-2 engine used on the S-II and S-IVB will be modified into the improved J-2X engine for use both on the Earth Departure Stage (EDS) as well as on the second stage of the proposed Ares I. Both the EDS and the Ares I second stage would use a single J-2X motor, although the EDS was originally designed to use two motors until the redesign employing the five (later six) RS-68Bs in place of the five SSMEs.

Cost

From 1964 until 1973, a total of US$6.5 billion was appropriated for the Saturn V, with the maximum being in 1966 with US$1.2 billion. Allowing for inflation this is equivalent to roughly $32–45 billion in 2007 money. This works out at an amortized cost of $2.4-3.5 billion per launch.

One of the main reasons for the cancellation of the Apollo program was the cost. In 1966, NASA received its highest budget of US$4.5 billion, about 0.5 percent of the GDP of the United States at that time.

Saturn V vehicles and launches

Serial Number	Mission	Launch Date	Notes
SA-501	Apollo 4	November 9, 1967	First test flight, a complete success.
SA-502	Apollo 6	April 4, 1968	Second test flight, with some serious second and third stage problems occurring.
SA-503	Apollo 8	December 21, 1968	First manned flight of Saturn V and lunar orbit
SA-504	Apollo 9	March 3, 1969	Earth orbit LM test
SA-505	Apollo 10	May 18, 1969	Lunar orbit LM test
SA-506	Apollo 11	July 16, 1969	First manned lunar landing
SA-507	Apollo 12	November 14, 1969	Landed near Surveyor 3. Vehicle was struck twice by lightning after liftoff with no serious damage.
SA-508	Apollo 13	April 11, 1970	Severe, near catastrophic pogo oscillations in second stage caused early center engine shutdown. Service Module O2 tank rupture caused mission abort en route to moon, crew saved.
SA-509	Apollo 14	January 31, 1971	Landed near Fra Mauro
SA-510	Apollo 15	July 26, 1971	First Lunar Rover
SA-511	Apollo 16	April 16, 1972	Landed at Descartes
SA-512	Apollo 17	December 6, 1972	First and only night launch; Final Apollo lunar mission
SA-513	Skylab 1	May 14, 1973	Two-stage Skylab version (Saturn INT-21)
SA-514	Unused		Designated but never used for Apollo 18/19
SA-515	Unused		Designated but never used as a backup Skylab launch vehicle

Currently there are three locations where Saturn Vs are on display:

• One at the Johnson Space Center made up of first stage of SA-514, the second stage from SA-515 and the third stage from SA-513. With stages arriving between 1977 and 1979, this was displayed in the open until its 2005 restoration when a structure was built around it for protection.

• One at the Kennedy Space Center made up of S-IC-T (test stage) and the second and third stages from SA-514. The vehicle was known as 500F when it was rolled out at LC-39 on May 26, 1966. It was displayed outdoors for decades, then in recent years was enclosed for protection from the elements.

• Two at the U.S. Space & Rocket Center in Huntsville:

:One made up of S-IC-D, S-II-F/D and S-IVB-D. These were all test stages not meant for actual flight. This was displayed outdoors for decades (and there is a poignant photo of Wernher von Braun standing next to it) and in recent years was enclosed in the Davidson Center for Space Exploration.

:Also in 1999, a Saturn V mockup was built and is located adjacently in a prominent upright display.

Of these three locations, only the one at the Johnson Space Center consists entirely of stages that were intended to be launched. Additionally, the S-IC stage from SA-515 resides on display at the Michoud Assembly Facility in New Orleans, Louisiana. The S-IVB stage from SA-515 was converted for use as a backup for Skylab. The Skylab backup is now on display at the National Air and Space Museum in Washington, D.C..

The blueprints or other plans for the Saturn V still exist on microfilm at the Marshall Space Flight Center.

Media

See also

• Comparison of super heavy lift launch systems

References

Notes

External links

NASA sites

• Apollo Lunar Surface Journal
• Saturn launch vehicles (PDF)
• Launch complex 39 facility description (PDF)
• Saturn Vs on display

Other sites

• Apollo Saturn Reference Page
• Project Apollo Archive
• Apollo/Saturn V Development ApolloTV.net Video

Simulators

• 3D Saturn V Explorer and Launch Simulation Program
• 3D Apollo Simulator with Saturn V Simulation Program
• Saturn V/Saturn IB simulation for Orbiter spaceflight sim