Space Shuttle design process
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Before the
Two designs emerged as front-runners. One was designed by engineers at the
All of this was taking place in the midst of other NASA teams proposing a wide variety of post-Apollo missions, a number of which would cost as much as Apollo or more[
When funding for the program came into question, there were concerns that the project might be canceled. This became especially pressing as it became clear that the
Decision-making process
In 1969, United States
- A human mission to Mars
- Follow-on lunar program
- A low Earth orbital infrastructure program
- Discontinuing human space activities
Based on the advice of the Space Council,
Shuttle design debate
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During the early shuttle studies, there was a debate over the optimal shuttle design that best-balanced capability, development cost, and operational cost. Initially, a fully reusable design was preferred. This involved a very large winged crewed
However, further studies showed a huge booster was needed to lift an orbiter with the desired payload capability. In space and aviation systems, the cost is closely related to mass, so this meant the overall vehicle cost would be very high. Both booster and orbiter would have rocket engines plus jet engines for use within the atmosphere, plus separate fuel and control systems for each propulsion mode. In addition, there were concurrent discussions about how much funding would be available to develop the program.
Another competing approach was maintaining the Saturn V production line and using its large payload capacity to launch a space station in a few payloads rather than many smaller shuttle payloads. A related concept was servicing the space station using the Air Force Titan III-M to launch a larger Gemini capsule, called "Big Gemini", or a smaller "glider" version of the shuttle with no main engines and a 15 ft × 30 ft (4.6 m × 9.1 m) payload bay.
The shuttle supporters answered that given enough launches, a reusable system would have lower overall costs than disposable rockets. If dividing total program costs over a given number of launches, a high shuttle launch rate would result in lower pre-launch costs. This in turn would make the shuttle cost-competitive with or superior to expendable launchers. Some theoretical studies mentioned 55 shuttle launches per year; however, the final design chosen did not support that launch rate. In particular, the maximum external tank production rate was limited to 24 tanks per year at NASA's Michoud Assembly Facility.
The combined space station and Air Force payload requirements were not sufficient to reach desired shuttle launch rates. Therefore, the plan was for all future U.S. space launches—space stations, Air Force, commercial satellites, and scientific research—to use only the Space Shuttle. Most other expendable boosters would be phased out.
The reusable booster was eventually abandoned due to several factors: high price (combined with limited funding), technical complexity, and development risk. Instead, a partially (not fully) reusable design was selected, where an external propellant tank was discarded for each launch, and the booster rockets and shuttle orbiter were refurbished for reuse.
Initially, the orbiter was to carry its own liquid propellant. However, studies showed carrying the propellant in an external tank allowed a larger payload bay in an otherwise much smaller craft. It also meant throwing away the tank after each launch, but this was a relatively small portion of operating costs.
Earlier designs assumed the winged orbiter would also have jet engines to assist maneuvering in the atmosphere after re-entering. However NASA ultimately chose a gliding orbiter, based partially on experience from previous rocket-then-glide vehicles such as the
Another decision was the size of the crew. Some said that the shuttle should not carry more than four, the most that could use
The last remaining debate was over the nature of the boosters. NASA examined four solutions to this problem: development of the existing Saturn lower stage, simple pressure-fed liquid-fuel engines of a new design, a large single solid rocket, or two (or more) smaller ones. Engineers at NASA's
Air Force involvement
During the mid-1960s the
NASA sought Air Force support for the shuttle. After the
Despite the potential benefits for the Air Force, the military was satisfied with its expendable boosters and did not need or want the shuttle as much as NASA did. Because the space agency needed outside support, the Defense Department (DoD) and the National Reconnaissance Office (NRO) gained primary control over the design process. For example, NASA planned a 40-by-15-foot (12.2 by 4.6 m) cargo bay, but NRO specified a 60-by-15-foot (18.3 by 4.6 m) bay because it expected future intelligence satellites to become larger. When Faget again proposed a 12 ft (3.7 m) wide payload bay, the military almost immediately insisted on retaining the 15 ft (4.6 m) width.[citation needed] The Air Force also gained the equivalent of the use of one of the shuttles for free despite not paying for the shuttle's development or construction. In exchange for the NASA concessions, the Air Force testified to the Senate Space Committee on the shuttle's behalf in March 1971.[3]: 216, 232–234 [6]
As another incentive for the military to use the shuttle, Congress reportedly told DoD that it would not pay for any satellites not designed to fit into the shuttle cargo bay.
Potential military use of the shuttle—including the possibility of using it to verify Soviet compliance with the
Final design
While NASA would likely have chosen liquid boosters had it complete control over the design, the
In the spring of 1972
The Space Shuttle program used the
Retrospection
![](http://upload.wikimedia.org/wikipedia/commons/thumb/4/42/SpaceShuttleGroundProcessingVision.jpg/220px-SpaceShuttleGroundProcessingVision.jpg)
Opinions differ on the lessons of the Shuttle. It was developed with the original development cost and time estimates given to President Richard M. Nixon in 1971,[12] at a cost of $6.744 billion in 1971 dollars (equivalent to $38.9 billion in 2023)[13] versus an original $5.15 billion estimate.[14] The operational costs, flight rate, payload capacity, and reliability have been different than anticipated, however.[12]
See also
- Buran (spacecraft)
- Single-stage-to-orbit
- Space Shuttle abort modes
- Space Shuttle program
- SpaceX Starship design process
- Studied Space Shuttle designs
References
- ^ "Report of the Space Task Group, 1969". NASA. Archived from the original on December 24, 2018. Retrieved August 6, 2009.
- from the original on August 2, 2017. Retrieved July 14, 2020.
- ^ a b c d Heppenheimer, T. A. (1998). The Space Shuttle Decision. NASA. Archived from the original on November 7, 2019. Retrieved July 12, 2017.
- ^ Day, Dwayne A. (January 11, 2010). "Big Black and the new bird: the NRO and the early Space Shuttle". The Space Review. Archived from the original on September 29, 2018.
- ^ "Columbia Accident Investigation Board Report: Volume 6, page 224". October 2003.
- ^ Day, Dwayne A. (November 20, 2006). "The spooks and the turkey". The Space Review. Archived from the original on March 15, 2019.
- ^ Aldridge, Edward. C. "Pete" Jr. (c. 1989). Assured Access: 'The Bureaucratic Space War' (PDF) (Technical report). Archived (PDF) from the original on October 28, 2022. Retrieved September 17, 2012.
- ^ Day, Dwayne (February 13, 2017). "Black ops and the shuttle (part 1)". The Space Review. Archived from the original on March 10, 2019. Retrieved February 27, 2017.
- ^ Berger, Eric (July 14, 2016). "A Cold War mystery: Why did Jimmy Carter save the space shuttle?". Ars Technica. Archived from the original on May 19, 2022. Retrieved February 2, 2023.
- hdl:2060/19740022195. NASA-CR-134338. Archived(PDF) from the original on April 5, 2023.
- hdl:2060/19810022557. NASA-CR-164695. Archived(PDF) from the original on August 1, 2023. Retrieved August 1, 2023.
- ^ a b "Columbia Accident Investigation Board Public Hearing". Columbia Accident Investigaion Board Report (PDF) (Technical report). Vol. VI. Houston, Texas (published October 2003). April 23, 2003. pp. 219–245. Archived (PDF) from the original on May 11, 2023.
- Gross Domestic Product deflatorfigures follow the MeasuringWorth series.
- Astronautix.com. Archived from the originalon July 12, 2016. Retrieved November 12, 2017.
Further reading
External links
- Astronautix Space Shuttle article
- NASA: The Space Shuttle Decision
- INTRODUCTION TO FUTURE LAUNCH VEHICLE PLANS [1963–2001], M. Lindroos
- 10 Space Shuttles which never flew (Lockheed Starclipper, Chrysler SERV, Phase B Shuttles, Rockwell C-1057, Shuttle C, Air Launched Sortie Vehicle (ALSV), Hermes, Buran, Shuttle II, Lockheed Martin VentureStar)