A year ago today, the Space Shuttle Orbiter Atlantis was docked with the International Space Station (ISS). On 21 July 2011, it deorbited and landed back on Earth, ending 30 years of Space Shuttle flights. The decision to end the Shuttle Program after ISS completion was taken by President George W. Bush in 2004. The Space Shuttles successor, the Orion capsule, was not ready when Atlantis returned to Earth. Fortunately, the 20-year cooperative relationship with the Russian space program ensured that American astronauts could continue to live and work on board the ISS.

Although the fact is mostly forgotten today, NASA launched plans to replace the Space Shuttle even before the first Space Shuttle mission in April 1981. In 1985,President Ronald Reagan formalized these by signing a directive ordering the U.S. civilian space agency to develop a Space Shuttle successor. Notably, this occurred before the January 1986 Challenger accident laid bare the Space Shuttles frailties. NASA has attempted to develop a Space Shuttle successor ever since, but for a wide range of reasons it has not succeeded.

One of the early proposed Shuttle successors was called Shuttle II. The lions-share of Shuttle II design work took place at NASAs Langley Research Center (LaRC) in Hampton, Virginia. Shuttle II first achieved prominence in 1986in the high-level National Commission On Space report. LaRCs Shuttle II design evolved for a time it was to have been a single-stage-to-orbit vehicle although typically it included a winged manned Orbiter and awinged unmanned Booster, both of which would have landed on runways and been entirely reusable. The Shuttle II Orbiters fuselage would have been crammed full of propellant tanks, so it would have toted cargo in a sizable hump on its back.

NASA LaRCs Shuttle II. Image: NASA.

Shuttle II was intended mainly as a crew transport complementing a mixed fleet of launchers that would have included unmanned heavy-lift rockets capable of placing from 50 to 100 tons into space. It would have transported a small amount of cargo perhaps 10 tons and a large number of astronauts between 10 and as many as 25 to an established, mature Space Station. Only a handful of astronauts perhaps three would have been Shuttle II crewmembers; the remainder would have been considered passengers. Upon reaching space on board Shuttle II, they would have eitherserved aboard the Space Station or transferred to spacecraft bound for the moon or Mars.

Although a good case can be made for calling LaRCs Shuttle II theShuttle II, it was in fact notthe only proposed Shuttle II design. The Advanced Programs Office at NASA Johnson Space Center (JSC) in Houston, Texas, put forward the sleek Shuttle II design depicted in the images that follow. The LaRC design was favored by NASA Headquarters and is relatively well documented. Neither can be said for JSCs design. These images NASA photos of a model constitute a rare glimpse at a spaceship that never was.

NASA JSCs Evolved Shuttle. Image: NASA.

Engineers in Houston envisioned that their Shuttle II might develop from an Evolved Space Shuttle. In the Evolved Shuttle, Liquid Replacement Boosters would have stood in for the Space Shuttles Solid Rocket Boosters, though the Evolved Shuttle would have retained the Space Shuttles expendable External Tank and, with minor modifications, the Space Shuttle Main Engines (SSMEs). Winglets on the tips of the Evolved Shuttles modified delta wings would have replaced the Space Shuttles single vertical tail fin. Redesigned Orbital Maneuvering System (OMS) engines based on the venerable RL-10 engine would have drawn liquid hydrogen/liquid oxygen propellants from tanks in the wings.

The most dramatic change, however, wasreserved for the crew compartment. It would have been completely redesigned so that it could separate from the rest of the Evolved Shuttle in the event of a catastrophic failure and operate as an independent small piloted spacecraft. This feature, along with the wing configuration, would carry over to JSCs Shuttle II design.

NASA JSC engineers gave no indication of when they expected the transition from Space Shuttle to Evolved Shuttle would occur. If one assumes, however, that JSCs Shuttle II would have become operational in the first years of the 21st century like LaRCs Shuttle II then the Evolved Shuttle would probably have flown during the 1990s.

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NASA Johnson Space Center's Shuttle II (1988)