Its origins were as a man-tended free-flying space station consisting of a pressurized module based on Spacelab, payload carriers based on Eureca platform technologies, and a new Resource Module that would provide power, communications, guidance, navigation and control to the other modules.
The European Space Agency (ESA) became an increasingly important factor in space during the late 1970s and early 80s. Europe's 'Ariane' launch vehicle was a huge commercial success and ESA also built the 'Spacelab' pressurized laboratory module for the American Space Shuttle program. Spacelab contractors such as MBB and Alitalia started to examine possible follow-on manned projects, including independent ESA space stations. German and Italian companies had already proposed an integrated European manned spaceflight program named 'Columbus' when President Reagan invited other countries to join the US-led Space Station program.
The option initially favored by the Europeans would have been capable of undocking from the US Space Station complex to perform sensitive microgravity experiments in an unmanned mode. The total estimated cost was 1750 million European Currency Units and Germany was willing to fund up to 50% with Italy providing 25%. The Europeans were also looking at space transportation elements to complement the Eureca platform and Columbus space station. Candidates included a winged reusable booster rocket for the Ariane-5 and a multipurpose 'space tug' for servicing satellites as well as transporting cargo to Columbus.
Article by Marcus Lindroos