For anyone old enough to remember the 1980s, the Space Shuttle was an iconic symbol of spaceflight. For thirty years (1981-2011), this program flew 135 missions, which consisted of orbital science experiments, deploying satellites, launching interplanetary probes, participating in the Shuttle-Mir program, deploying the Hubble Space Telescope (HST), and constructing the International Space Station (ISS). There were also tragedies along the way, such as the Challenger (1986) and Columbia disasters (2003).
But here’s an interesting and little-known fact: the actual design of the Space Shuttle could have been entirely different. Rather than the reusable Space Transportation System (STS) and expendable external tank (E.T.) and solid rocket boosters (SRB) we all remember, there was also a concept for a fully-reusable two-stage-to-orbit spaceplane (DC-3). In a lovely video by spaceflight animator Haze Gray Art (YouTube handle Hazegrayart), viewers get a chance to see what a full take-off and landing would have looked like.
Before the Apollo Program had fulfilled its goal of sending astronauts to the Moon to conduct lunar science and “win the Space Race,” NASA was contemplating what its next steps would be. This included mission architectures that would complement the achievements of the Mercury, Gemini, and Apollo programs and possible spacecraft that would replace the Saturn V super-heavy launch system.
On the one hand, some advocated mounting crewed missions to Mars, which was seen as the next logical step. As the summer of 1969 came around and the Apollo 11 mission achieved the “Moon Landing,” these voices were amplified. Alternately, there were proposals that emphasized “preeminence in Earth orbital, lunar, and planetary activities” first, which would gradually lead to a human Mars landing.
These latter proposals stressed that reusability and cost-effectiveness were to be emphasized moving forward. In 1968, George Mueller, the head of NASA’s Office of Manned Space Flight (OMSF), issued a request for proposals for Integrated Launch and Re-entry Vehicle (ILRV) to meet these requirements. This led to the Space Task Group (STG) formation to determine the optimal design for a reusable spacecraft and issued contracts to commercial partners.
By September 1969, the STG issued a report titled “The Post-Apollo Space Program: Directions for the Future.”
“[D]evelop new systems and technology for space operations with emphasis upon the critical factors of: (1) commonality, (2) reusability, and (3) economy, through a program directed initially toward development of a new space transportation capability and space station modules which utilize this new capability promote a sense of world community through a program which provides opportunity for broad international participation and cooperation.”
The report also created three classes of a future reusable shuttle:
- Class I: a reusable orbiter mounted on expendable boosters
- Class II: multiple expendable rocket engines and a single propellant tank (stage-and-a-half)
- Class III: both a reusable orbiter and a reusable booster
Concurrently, NASA’s Mission Design Center (MDC) began considering possible spacecraft designs to fulfill these objectives in July 1969. By December, the MDC issued their final report, titled “Two Stage-Fixed Wing Space Transportation System.” As is stated in the report:
“The growth of future manned space expoloration is dependent upon the development of a reusable space transportation system with operational practices similar to present day air-craft procedures. Such a system could achieve a dramatic reduction of operational costs and allow a rapid expansion of space flight.
“A two stage configuration satisfying these requirements has been conceived by NASA-MSC. An important feature of this configuration is that both the orbiter and booster have fixed wings and tail and look similar to conventional aircraft. Tre fixed wing provides good subsonic cruise and horizontal landing characteristics which are very similar to present day high performance aircraft.”
In short order, two designs emerged as front-runners. One called for a fixed-winged orbiter with an expendable propellant tank and solid boosters. Advocates for this design emphasized that it would allow for a greater payload capability, though predicted costs would be higher. By January 1971, NASA and the U.S. Air Force opted for this design, which is how the Space Shuttle came to be.
The other proposal, which was passed over, was for a two-stage system designed by engineers at the NASA Manned Spaceflight Center (MSC) and championed by George Mueller. The design was later simplified by NASA engineer Maxime Faget, whose previous work included the design of the Mercury capsule. This became the DC-3, a two-stage fully recoverable system with a fixed-winged orbiter mounted on a larger straight-winged booster.
The details are beautifully rendered in the animation. It begins with the DC-3 STS launching atop a 10-engine booster, then relying on two rocket engines to reach LEO. A powered landing is also shown, and a final shot of the STS in orbit where it delivers a module to a growing space station. This gives viewers a chance to see what might have been had NASA gone with the DC-3 option instead.
Much like the Buran space shuttle developed by the Soviets before the collapse, the DC-3 is one of many concepts that emerged during the Space Age but never got its due. Such is life! The Space Shuttle Era officially ended in 2011 with the retirement of the remaining fleet. With the exception of the Challenger and Columbia disasters, it’s fair to say that NASA has no regrets about the path it chose.
In addition to the vital research conducted in orbit, the deployment of Hubble, the creation of the ISS, and many historic achievements, the Space Shuttle validated technologies that now inform next-generation missions like the Dreamchaser, X-37B, AstroClipper, and the Shenlong spacecraft (and maybe the Skylon!)
It also tested and validated spacecraft reusability, which has since been commercialized by companies like SpaceX, United Launch Alliance (ULA), Virgin Galactic, Blue Origin, Rocket Lab, and others. Thanks to the cooperative relationship between NASA and these contractors, crewed launch capability was restored to U.S. soil in 2020 with the launch of the Crew-1 mission.
Much of the leftover infrastructure and components of the Space Shuttle Program – like Solid Rocket Boosters (SRBs) – are now being used for the Space Launch System (SLS), the super-heavy launch system and successor to the Saturn V. As always, it’s impossible to appreciate the path forward without understanding the path behind us. But sometimes, it’s nice to contemplate the paths we didn’t take!