Saturn IB version
Saturn IB Saturn IB (final production run, 1973–1975)
The last Saturn IB production run — vehicles SA-206 to SA-210 — flew between 1973 and 1975. Another round of first-stage engine improvements lifted its low Earth orbit capability to 21,000 kg. It ferried all three Skylab crews and the American half of the joint mission with the Soviet Union, always from LC-39B and always perched on the raised platform nicknamed the milkstool. These rockets dropped the black-and-white paint scheme of the earlier vehicles.
- May 25, 1973
- First launch
- 21,000 kg
- LEO capacity
- 7,100 kN
- Thrust
- No
- Reusable
History
Surplus hardware, new job
With the lunar programme over, NASA had Saturn IBs left in inventory and a space station, Skylab, that needed crews delivered. The rocket was fit for the task; the ground infrastructure was not. LC-34 and LC-37 had been shut down, so the launches moved to LC-39B, built for a far larger vehicle. The fix earned its own nickname: Mobile Launcher Platform No. 1 received a raised pedestal, the milkstool, lifting the Saturn IB until the umbilical tower's access arms lined up with the spacecraft and the S-IVB, while the arms meant for the Saturn V's second stage were reworked to serve the S-IB.
The Skylab shuttle service
SA-206 lifted the first Skylab crew on 25 May 1973; SA-207 followed on 28 July and SA-208 on 16 November of the same year. The profile never varied: the launch vehicle placed the command and service module in a 150 by 222 km elliptical orbit coplanar with the station's, and the spacecraft's own SPS engine performed a Hohmann transfer at apogee up to Skylab's 431 km. A standby rescue vehicle, SA-209, was prepared for each stay and never needed.
Apollo–Soyuz and the last flight
On 15 July 1975 SA-210 launched the American element of the Apollo–Soyuz Test Project, an Apollo CSM fitted with a special docking module for the rendezvous with Soyuz 19. No Saturn IB flew again. The survivors were scrapped: no mission could be found for them, and the country's heavy-lift needs could be met more cheaply and flexibly by the Titan III family and the Space Shuttle. A Saturn IB with its launch had cost 55,000,000 dollars in 1972.
What survives
Pieces of the run are scattered across museums. SA-209 stands at the Kennedy Space Center Visitor Complex, its corroded first-stage engines and service module replaced by fabricated duplicates. The SA-211 S-IVB sits in Huntsville alongside Skylab underwater-training hardware, while that vehicle's first stage stood stacked with a mock-up at Ardmore, Alabama from July 1979 until 2023, when four decades of weather left it beyond repair and dismantling began. SA-212 left the most durable legacy of all: its S-IVB became Skylab itself.