Saturn IB

History

In 1959, NASA's Silverstein Committee issued recommendations to develop the Saturn class launch vehicles, growing from the C-1. When the Apollo program was started in 1961 with the goal of landing men on the Moon, NASA chose the Saturn I for Earth orbital test missions. However, the Saturn I's payload limit of 20000 lb to 162 km would allow testing of only the command module with a smaller propulsion module attached, as the command and service module would have a dry weight of at least 26300 lb, in addition to service propulsion and reaction control fuel. In July 1962, NASA announced selection of the C-5 for the lunar landing mission, and decided to develop another launch vehicle by upgrading the Saturn I, replacing its S-IV second stage with the S-IVB, which would also be modified for use as the Saturn V third stage. The S-I first stage would also be upgraded to the S-IB by improving the thrust of its engines and removing some weight. The new Saturn IB, with a payload capability of at least 16000 kg, would replace the Saturn I for Earth orbit testing, allowing the command and service module to be flown with a partial fuel load. It would also allow launching the 32000 lb lunar excursion module separately for uncrewed and crewed Earth orbital testing, before the Saturn V was ready to be flown. It would also give early development to the third stage.

On May 12, 1966, NASA announced the vehicle would be called the "uprated Saturn I", at the same time the "lunar excursion module" was renamed the lunar module. However, the "uprated Saturn I" terminology was reverted to Saturn IB on December 2, 1967.

By the time it was developed, the Saturn IB payload capability had increased to 41000 lb. By 1973, when it was used to launch three Skylab missions, the first-stage engine had been upgraded further, raising the payload capability to 46000 lb.

Specifications

Launch vehicle

Payload configurations

S-IB first stage

Main article: S-IB

The S-IB stage was built by the Chrysler corporation at the Michoud Assembly Facility, New Orleans. The four outboard engines were mounted on gimbals, allowing them to be steered to control the rocket. Eight fins surrounding the base thrust structure provided aerodynamic stability and control.

Data from:

S-IVB second stage

Main article: S-IVB

The S-IVB was built by the Douglas Aircraft Company at Huntington Beach, California. The S-IVB-200 model was similar to the S-IVB-500 third stage used on the Saturn V, with the exception of the interstage adapter, smaller auxiliary propulsion control modules, and lack of on-orbit engine restart capability. It was powered by a single Rocketdyne J-2 engine. The fuel and oxidizer tanks shared a common bulkhead, which saved about ten tons of weight and reduced vehicle length over ten feet.

Instrument unit

Main article: Saturn V instrument unit

IBM built the instrument unit at the Space Systems Center in Huntsville, Alabama. Located at the top of the S-IVB stage, it consisted of a Launch Vehicle Digital Computer (LVDC), an inertial platform, accelerometers, a tracking, telemetry and command system and associated environmental controls. It controlled the entire rocket from just before liftoff until battery depletion. Like other rocket guidance systems, it maintained its state vector (position and velocity estimates) by integrating accelerometer measurements, sent firing and steering commands to the main engines and auxiliary thrusters, and fired the appropriate ordnance and solid rocket motors during staging and payload separation events.

As with other rockets, a completely independent and redundant range safety system could be invoked by ground radio command to terminate thrust and to destroy the vehicle should it malfunction and threaten people or property on the ground. In the Saturn IB and V, the range safety system was permanently disabled by ground command after safely reaching orbit. This was done to ensure that the S-IVB stage would not inadvertently rupture and create a cloud of debris in orbit that could endanger the crew of the Apollo CSM.

Launch sequence events

Acceleration of the Saturn IB increased from 1.24 G at liftoff to a maximum of 4.35 G at the end of the S-IB stage burn, and increased again from 0 G to 2.85 G from stage separation to the end of the S-IVB burn.

AS-206, 207, and 208 inserted the Command and Service Module in a 150 by elliptical orbit which was co-planar with the Skylab one. The SPS engine of the Command and Service Module was used at orbit apogee to achieve a Hohmann transfer to the Skylab orbit at 431 km.

Saturn IB vehicles and launches

The first five Saturn IB launches for the Apollo program were made from LC-34 and LC-37, Cape Kennedy Air Force Station.

The Saturn IB was used between 1973 and 1975 for three crewed Skylab flights, and one Apollo–Soyuz Test Project flight. This final production run did not have alternating black and white S-IB stage tanks, or vertical stripes on the S-IVB aft tank skirt, which were present on the earlier vehicles. Since LC-34 and 37 were inactive by then, these launches utilized Kennedy Space Center's LC-39B. Mobile Launcher Platform No. 1 was modified, adding an elevated platform known as the "milkstool" to accommodate the height differential between the Saturn IB and the much larger Saturn V. This enabled alignment of the Launch Umbilical Tower's access arms to accommodate crew access, fueling, and ground electrical connections for the Apollo spacecraft and S-IVB upper stage. The tower's second stage access arms were modified to service the S-IB first stage.

For earlier launches of vehicles in the Saturn I series, see the list in the Saturn I article.

Saturn IB rockets on display

As of 2023 there are two locations where Saturn IB vehicles (or parts thereof) are on display:

• SA-209 is on display at the Kennedy Space Center Visitor Complex, with the Apollo Facilities Verification Vehicle. Due to severe corrosion, the first stage engines and service module were replaced with fabricated duplicates in 1993–1994.
• The SA-211 S-IVB stage was mated with the Skylab underwater training docking adapter and Apollo Telescope Mount and is on display in the Rocket Garden of the U.S. Space & Rocket Center in Huntsville, Alabama. The SA-211 first stage was on display with a mockup S-IVB stage stacked in a launch-ready condition at the Alabama Welcome Center on Interstate 65 in Ardmore, Alabama, since July 1979. The structural integrity of the display, after four decades of weathering, could not be repaired. Dismantling of the vehicle for disposal began by September 14, 2023.

Cost

In 1972, the cost of a Saturn IB including launch was .

Notes

References

References

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4. (May 1966). "Postlaunch report for mission AS-201 (Apollo spacecraft 009) -". NASA.
5. "Saturn I".
6. NASA Marshall Spaceflight Center, Skylab Saturn IB Flight Manual (MSFC-MAN-206), 30 September 1972
7. (September 30, 1972). "Skylab Saturn 1B Flight Manual -". NASA.
8. Reynolds, David West. (2006). "Kennedy Space Center: Gateway to Space". Firefly Books Ltd..
9. (14 September 2023). "Historic Alabama welcome center rocket dismantling begins".
10. "Saturn IB History".
11. Dooling, Dave. (May 6, 1979). "Space and Rocket Plans Summer Celebration". [[The Huntsville Times]].
12. Hughes, Bayne. (April 6, 2014). "Iconic rocket due for repair". [[The Decatur Daily]].
13. "SP-4221 The Space Shuttle Decision- Chapter 6: Economics and the Shuttle". NASA.