Saturn C-3

The Marshall Space Flight Center in Huntsville, Alabama developed an Earth orbit rendezvous proposal (EOR) for the Apollo program in 1960-1961. The proposal used a series of small rockets half the size of a Saturn V to launch different components of a spacecraft headed to the Moon. These components would be assembled in orbit around the Earth, then sent to the Moon via trans-lunar injection. In order to test and validate the feasibility of the EOR approach for the Apollo program, Project Gemini was founded with this objective: "To effect rendezvous and docking with another vehicle (Agena target vehicle), and to maneuver the combined spacecraft using the propulsion system of the target vehicle".

The Saturn C-3 was the primary launch vehicle for Earth orbit rendezvous. The booster consisted of a first stage containing two Saturn V F-1 engines, a second stage containing four powerful J-2 engines, and the S-IV stage from a Saturn I booster. Only the S-IV stage of the Saturn C-3 was developed and flown, but all of the specified engines were used on the Saturn V rocket which took men to the Moon.[4]

The concept of Lunar orbit rendezvous (LOR) was studied at Langley Research Center as early as 1960. John Houbolt's memorandum advocating LOR for lunar missions in November 1961 to Robert Seamans outlined the usage of the Saturn C-3 launch vehicle, and avoiding complex large boosters and lunar landers.[5]

After six months of further discussion at NASA, in the summer of 1962, Langley Research Center‘s Lunar orbit rendezvous (LOR) proposal was officially selected as the mission configuration for the Apollo program on November 7, 1962.[6] By the end of 1962, the Saturn C-3 design was deemed not necessary for Apollo program requirements as larger boosters (Saturn C-4, Saturn C-5) were then proposed, hence further work on the Saturn C-3 was cancelled.[7]

The Saturn C-3B revision (1961) increased the total thrust of the three stages to 17,200 kN. The diameter of the first stage (S-IB-2) was increased to 33 feet (10 meters). The eventual first stage for the Saturn V (S-IC) would use this same diameter, but add 8 meters to its length. A further consideration added a third F-1 engine to the first stage. The S-II, second stage diameter would be 8.3 meters (326 inches) and 21.3 meters (70 feet) in length.

The 3-stage version would use the S-IV stage, with a diameter of 5.5 meters and 12.2 meters in length.

The Saturn C-3BN revision (1961) would use the NERVA for the third stage in this launch vehicle. The NERVA technology has been studied and proposed since mid-1950s for future space exploration.

Saturn INT-20C, Boeing proposal (1966)

On 7 October 1966, Boeing submitted a Final Report to the NASA Marshall Space Flight Center, "Studies of Improved Saturn V Vehicles and Intermediate Payload Vehicles". That report outlined the Saturn INT-20, an intermediate two-stage launch vehicle with an S-1C first stage using three or four F-1 engines, and an S-IVB as the second stage with one J-2 engine. The vehicle's payload capacity for LEO would be 45,000 to 60,000 kg, comparable to the earlier Saturn C-3 design (1961). Boeing projected delivery and first flight in 1970, based on a decision by 1967.

After the Space Shuttle Challenger disaster, the United States Air Force (USAF) and National Aeronautics and Space Administration (NASA) conducted a joint Advanced Launch System study (1987-1990). Hughes Aircraft and Boeing dusted off the earlier Saturn C-3 design and submitted their proposal for the Jarvis launch vehicle.

The Jarvis would be a three-stage rocket, 58 m (190 ft) in height and 8.38 m (27.5 ft) in diameter. Designed to lift 38 tons to LEO, it would utilize F-1 and J-2 rocket engines and tooling in storage from the Saturn V rocket program along with more recent Shuttle-era technologies to provide lower launch costs.[8]

Pyrios is an advanced booster concept proposed in 2012 by Dynetics for use on NASA's Space Launch System heavy-lift launch vehicle. Pyrios was intended to use the RP-1/LOX F-1B, a modernized version of the F-1A engine built by Aerojet Rocketdyne. Developed during the later stages of the Apollo program, the F-1A was test-fired but never flew. Several were created and stored by Rocketdyne. The company has also maintained an F-1/F-1A knowledge retention program for its engineers for the entire period the engine has been mothballed. Dynetics is now performing tests on engine components pulled from storage. Pyrios was intended to use the same attachment points as the five-segment SRBs[9]

The Dynetics booster would attach at these points and apply thrust to an upper thrust beam in the SLS core, rather than at the bottom. Like Saturn C-3 first stage, the proposed Dynetics booster would employ two F-1(A) heritage engines.[10][11]

The manager of NASA's SLS advanced development office indicated that the Pyrios proposal was viable.[12]

The planned 2015 competition in support of SLS Block 1A, was cancelled after studies and testing determined that the advanced booster would have resulted in unsuitably high acceleration and poor abort scenarios (manned crew).[13]. Based on the conclusions of this study, NASA cancelled the SLS Block 1A configuration.[14]

The need for Advanced Booster with SLS Block 2 is not expected until late 2020s.

 This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.