Editing Europa (rocket) (section)

===Collaboration===
As early as 1961, [[Peter Thorneycroft, Baron Thorneycroft|Peter Thorneycroft]], the Minister of Aviation, had been thinking about a joint European project, in order not to waste the advanced development of the Blue Streak, and not to leave space exploration to the Americans and Russians. Britain made diplomatic approaches to various European nations: the most significant of these was to France.<ref name="hill 14"/> Overtures between the [[British government]] and the [[French government]] on potential cooperation on missile research, and specifically on the potential use of the Blue Streak as early as 1957.<ref name="hill 135"/> Britain and France agreed to serve as the lead nations on the envisioned programme, but recognised that other partner nations would be necessary.<ref name="hill 136">Hill 2001, p. 136.</ref>

Both France and Britain approached various other nations to join on the collaborative programme, however negotiations with interested nations were often protracted, in part due to scepticism; author C.N. Hill stated that "many countries thought that the U.K. was seeking to foist an obsolescent launch vehicle on them, and making them pay the costs".<ref name="hill 136 137">Hill 2001, pp. 136-137.</ref> The participation of many nations hinged upon gaining the endorsement of Germany, which was eventually won over and chose to participate.<ref name="hill 137 139">Hill 2001, pp. 137-139.</ref> As a result of this diplomacy, it was decided to proceed with the formation of the [[European Launcher Development Organisation]] (ELDO) group.<ref name="hill 137 140">Hill 2001, pp. 130, 139-140.</ref>

The headquarters of ELDO were in [[Paris]]. The founding members were Belgium, France, the United Kingdom, Italy, the Netherlands and West Germany: Australia, Spain, Switzerland, Norway, and Sweden had chosen not to participate.<ref name="hill 239 140">Hill 2001, pp. 139-140.</ref> ELDO not only served the purpose of harnessing Blue Streak, but also fulfilled ambitions to produce a European rival to the American and Soviet launchers being developed and deployed at that time.<ref name="hill 135"/> In response to the rise of the ELDO initiative, work on the competing Black Prince launcher gradually came to a halt as attention from the British government drifted towards European collaboration.<ref name="hill 130">Hill 2001, p. 130.</ref>

After studying various designs and concepts, ELDO arrived at a three-stage approach which was given the designation ''Eldo A''; this was later formally named as ''Europa''.<ref name="hill 141">Hill 2001, p. 141.</ref> According to Hill, Black Prince and Europa were comparable launchers, capable of delivering similar performance and roughly the same payloads; the overlap left little room for both programmes. However, there was criticisms that Europa would take longer to deliver than the Black Prince launcher for no significant improvement, while suffering from the same core economic problem of being too expensive for scientific satellites while too small for commercial communications satellites.<ref name="hill 141 143">Hill 2001, pp. 141-143.</ref>

In January 1965, the French thought the initial three-stage rocket design would not be sufficiently advanced to carry the size of payloads required, while another rocket – referred to as ''Eldo B'' – which featured liquid [[hydrogen]]-fuelled second and third stages, came to be viewed as a superior design, partly due to reduce the cost of the project by eliminating transition test launchers. It would still use the Blue Streak as the first stage. The ELDO later disagreed, but the French would ultimately get their way when Eldo B became the foundation for the later [[Ariane 1|Ariane]] launcher, which first launched in 1979.