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Saturn INT-21
Size
Function	Launch vehicle
Manufacturer	Boeing (S-IC) North American (S-II)
Country of origin	United States
Height	98.5 m (323 ft) (without payload)
Diameter	10.06 m (33.0 ft)
Mass	2,916,080 kg (6,428,860 lb)
Stages	2
Capacity
Payload to LEO
Mass	115,900 kg (255,500 lb)^[1]

Launch history
Status	Study
Launch sites	LC-39A, Kennedy Space Center
Total launches	0

First stage – S-IC
Powered by	5 Rocketdyne F-1
Maximum thrust	34.02 MN (7,650,000 lb_f)
Burn time	150 seconds
Propellant	RP-1 / LOX
Second stage – S-II
Powered by	5 Rocketdyne J-2
Maximum thrust	5 MN (1,100,000 lb_f)
Burn time	360 seconds
Propellant	LH₂ / LOX

[edit on Wikidata]

The Saturn INT-21 was a study for an American orbital launch vehicle of the 1970s. It was derived from the Saturn V rocket used for the Apollo program, using its first and second stages, but lacking the third stage. The guidance unit would be moved from the top of the third stage to the top of the second stage. The INT-21 was never flown.

A related variant was launched once, from the Kennedy Space Center, Florida carrying the Skylab space station into orbit, at 17:30 UTC, on May 14, 1973.^[2] As Skylab was built from an S-IVB stage, there was no need to move the guidance unit. This version was intended to be used for other flights in the Apollo Applications Program, and would have also been used to launch other American space stations, including Skylab B.

Orbital launch systems

Orbital launch systems
List of orbital launch systems Comparison of orbital launch systems
Current	Angara 1.2 A5 Atlas V Ceres 1 1S Chollima-1 Delta IV Heavy Electron Epsilon Falcon 9 Block 5 Falcon Heavy Firefly Alpha GSLV H-IIA H3^† Hyperbola-1 Jielong 1 3 Kaituozhe 2 Kinetica-1 Kuaizhou 1 1A 11 Long March 2C 2D 2F 3A 3B/E 3C 4B 4C 5 5B 6 6A 7 7A 8 11 11H LVM3 Minotaur I IV V C Nuri OS-M1^† Pegasus XL Proton-M PSLV Qaem 100^† Qased RS1^† Shavit 2 Simorgh^† SLS Block 1 Soyuz-2 2.1a / STA 2.1b / STB 2-1v SSLV Starship^† Tianlong-2 Unha Vega original C Zenit 3SL 3SLB 3F Zhuque 1^† 2
In development	Amur Antares 330 Ariane 6 Bloostar Cyclone-4M Eris Hyperbola-2 Irtysh Kuaizhou 21 31 Long March 9 10 Miura 5 MLV Neutron New Glenn New Line 1 OS-M 2 4 Orbex Prime Pallas-1 Qaem-100 Red Dwarf SLS Block 1B Block 2 Soyuz-7 Terran R VLM Vega E Vulcan Zero Zuljanah
Retired	Antares 110 120 130^† 230 230+ Ariane 1 2 3 4 5 ASLV Athena I II Atlas B D E/F G H I II III LV-3B SLV-3 Able^† Agena Centaur Black Arrow Conestoga^† Delta A B C D E G J L M N 0100 1000 2000 3000 4000 5000 II III IV Diamant Dnepr Energia Europa I^† II^† Falcon 1 Falcon 9 v1.0 v1.1 v1.2 "Full Thrust" Feng Bao 1 GSLV Mk I H-I H-II H-IIB Juno I Juno II Kaituozhe-1 Kosmos original 1 2/2I 3 3M Lambda 4S LauncherOne Long March 1 1D^† 2A 2E 3 3B 4A Mu 4S 3C 3H 3S 3SII V N1^† N-I N-II Naro-1 Paektusan^† Pilot-2^† R-7 Luna Molniya M L Polyot Soyuz original FG L M U U2 Soyuz/Vostok Sputnik Voskhod Vostok L K 2 2M R-29 Shtil' Volna^† Rocket 3 Safir 1 1A 1B Saturn I IB V Scout X-1 Blue Scout II^† X-2^† X-2M X-3 X-3M X-4 X-2B^† B A B-1 D-1 A-1 E-1 F-1 G-1 Shavit original 1 SLV Space Shuttle SPARK^† Sparta SS-520 Start-1 Terran 1^† Thor Able Ablestar 1 2 Agena A B D Burner 1 2 Delta DSV-2U Thorad-Agena SLV-2G SLV-2H Titan II GLV IIIA IIIB IIIC IIID IIIE 34D 23G CT-3 IV Tsyklon R-36-O original 2 3 Universal Rocket UR-500 Proton Proton-K Rokot Strela Vanguard VLS-1^† Zenit 2 2M 2FG
Classes	Sounding rocket Small-lift launch vehicle Medium-lift launch vehicle Heavy-lift launch vehicle Super heavy-lift launch vehicle
This Template lists historical, current, and future space rockets that at least once attempted (but not necessarily succeeded in) an orbital launch or that are planned to attempt such a launch in the future Symbol ^† indicates past or current rockets that attempted orbital launches but never succeeded (never did or has yet to perform a successful orbital launch)

Orbital launch systems developed in the United States

Orbital launch systems developed in the United States
Active	Atlas V**^†† Delta IV Heavy^†† Electron Falcon 9 Block 5 Falcon Heavy Firefly Alpha Minotaur I IV V C Pegasus XL RS1^† SLS Block 1 Starship^†
In development	Antares 330 Daytona Firefly Beta New Glenn Neutron Red Dwarf SLS Block 1B Block 2 Terran R Vulcan
Retired	Antares 110/120/130/230/230+^††† Athena I II Atlas B D E/F G H I II III LV-3B SLV-3 Able Agena Centaur Conestoga Delta A B C D E G J L M N 0100 1000 2000 3000 4000 5000 II III IV Falcon 1 Falcon 9 v1.0 v1.1 v1.2 "Full Thrust" H-I* Juno I Juno II LauncherOne N-I* N-II* Pilot Rocket 3 Saturn I IB V Scout Space Shuttle SPARK Sparta Terran 1 Thor Able Ablestar Agena Burner Delta DSV-2U Thorad-Agena Titan II GLV IIIA IIIB IIIC IIID IIIE 34D 23G CT-3 IV Vanguard
* - Japanese projects using US rockets or stages ** - uses Russian engines ^† - never succeeded ^†† - no new orders accepted ^††† - used Ukrainian first stage

Saturn launch vehicle family

Saturn launch vehicle family
Early proposals	Juno V Saturn A-1 A-2 B-1
"C" series	Saturn C-1 C-2 C-3 C-4 C-5 C-5N C-8
Saturn I series	Saturn I IB IB-CE IB-A IB-B IB-C IB-D INT-05 INT-11 INT-12 INT-13 INT-14 INT-15 INT-16 INT-27 LCB
Saturn II series	Saturn II INT-17 INT-18 INT-19
Saturn V series	Saturn V MLV V ELV INT-20 INT-21 INT-23 INT-24 INT-25 Saturn-Shuttle Saturn V-3 V-A V-B V-C V-D V-Centaur Jarvis

See also

References

External links