that all three vehicles would be crewed, however, when commenting during the mid-1980s, Smith observed that, due to technological advances, it would be possible for the booster units to be entirely automated using existing technology. See also List of space launch system designs HOTOL Space Shuttle Triamese References Citations Bibliography Hill, C.N. "A Vertical Empire: The History of the UK Rocket and Space Programme, 1950–1971." World Scientific, 2001. . Sharp, Dan. British Secret Projects 5: Britain's Space Shuttle. Crécy, 2016. External links Unreal Aircraft – Weird Wings – BAC MUSTARD MUSTARD scale model (white one in display case backside) ^ same as above ^ (See also Martin Marietta Spacemaster) Economist, 21 June 2013, Thunderbirds are gone: A British defence firm opens its archives to reveal flights of fancy that never flew MUSTARD at BAE Systems Mustard Cancelled space launch vehicles Tailless delta-wing aircraft Lifting bodies Crewed spacecraft Former proposed space launch system concepts Rocket-powered aircraft Space launch vehicles of the United Kingdom Spaceplanes