You may think that Elon Musk’s BFR launch system is ridiculous, but there were even crazier spacecraft which we almost launched into orbit.
The history of space exploration is filled with adventurous designs and risky decisions, especially during the space race between the United States and Soviet Russia.
However, there were also a collection of spacecraft designs which were approved and under construction when governments lost interest in space travel and pulled the required funding.
These craft include a European space shuttle, a Japanese spaceplane, and a craft which used a solar sail for propulsion.
Hermes was set to be the space shuttle for the European Space Agency (ESA), conducting manned missions to a planned European space station.
The craft was initially approved for development in November 1987, but was later cancelled due to high costs.
The plan was for Hermes to be launched into space on an Ariane 5 rocket, replacing the upper stage of the launch system.
While it shares many characteristics with NASA’s space shuttle, Hermes is much smaller and could support three astronauts.
No Hermes spaceplanes were ever built.
Boeing X-20 Dyna-Soar
Boeing was one of the first to design a spaceplane-like craft which could return to Earth by gliding.
It’s X-20 Dyna-Soar (Dynamic Soarer) project was approved in October 1957, but was cancelled just after construction began on the vehicle in 1963.
Boeing pitched Dyna-Soar as a space interceptor aircraft, which could have been used to sabotage enemy satellites and perform reconnaissance missions.
The spaceplane was built to use a lifting re-entry method to blast into space and use its control surfaces to “skip” off the atmosphere and back into space.
Neil Armstrong was secretly chosen for the Dyna-Soar programme before it was scrapped.
Sunjammer is not a convential spacecraft.
The craft has the biggest solar sail ever built and was constructed by US company L’Garde in 2013.
NASA originally planned to launch the craft into orbit in January 2015 aboard a SpaceX Falcon 9 rocket, but cancelled the mission prior to flight testing.
Sunjammer has a total surface area of over 1,200 square metres and is only 5μm thick, weighing 32kg.
The craft would have been able to collect data and manoeuvre its trajectory through space by adjusting gimballed vanes located at the tips of its four booms.
HOPE-X (H-2 Orbiting Plane, Experimental) was a planned sub-orbital craft which was a scaled-down prototype of a larger HOPE orbiter.
Developed by Japan’s space agency, the craft evolved into an unmanned cargo vehicle with automated approach and docking systems.
The craft was being developed until budget constraints and a number of failures resulted in the project being cancelled.
HOPE-X was developed for around 20 years and was cancelled in 2003.
Lockheed Star Clipper
Lockheed’s Star Clipper was a proposed alternative to the NASA space shuttle.
The project had a great influence on the eventual design of the space shuttle, thanks to its dropped tank design.
The proposed vehicle was a spaceplane which could re-enter the atmosphere at hypersonic speeds, after which it would fold out stowed wings and fire jet engines to land safely.
Two fuel tanks an the sides of the craft would supply fuel to an engine and jettison when empty.