Ariane 1 was the first rocket in the Ariane family of expendable launch systems. It was developed and operated by the European Space Agency (ESA), which had been formed in 1973, the same year that development of the launcher had commenced.
Ariane 1 was the first launcher to be developed with the primary purpose of sending commercial satellites into geosynchronous orbit. Crucially, it was designed with the ability of sending a pair of satellites into orbit on a single launcher, thus reducing costs. As the size of satellites grew, Ariane 1 quickly gave way to the more powerful Ariane 2 and Ariane 3 launchers, which were heavily based upon the original rocket. The Ariane 4 was the last rocket to heavily draw upon the Ariane 1, as the successor rocket Ariane 5 uses a far greater proportion of all-new elements.
In 1975, eleven European countries decided to pursue joint collaboration in the field of space exploration and formed a new pan-national organisation to undertake this mission, the European Space Agency (ESA). For some time prior to the ESA's formation, France had been lobbying for the development of a new European expendable launch system to serve as a replacement for the Europa rocket; one proposed successor in the form of a refined Europa, referred to as the Europa IIIB, was studied but was found to be too ambitious and costly. As a result, the Europa IIIB proposal was scaled back and soon reemerged as the L3S. Multinational effort became a quick focus point for the L3S proposal; early on, emphasis was placed upon cooperation on the initiative between Germany and France, while increasing contribution from other countries also came into the picture over time.
In January 1973, Willy Brandt, the Chancellor of Germany, formally agreed to the L3S project following a series of personal approaches by Georges Pompidou, the President of France. On 21 September 1973, the legal agreement for the L3S, was signed. Under this agreement, the Europa III was formally cancelled, while the L3S would be developed as a multinational project.