Editing Ariane 4 (section)

=== Origins ===
In 1973, eleven nations 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).<ref name="harvey-2003">{{cite book |first=Brian |last=Harvey |title=Europe's Space Programme: To Ariane and Beyond |year=2003 |publisher=Springer Science & Business Media |isbn=1-8523-3722-2 }}</ref>{{rp|pages=161-162}} Six years later, in December 1979, the arrival of a capable European [[expendable launch system]] was marked when the first [[Ariane 1]] launcher was successfully launched from the [[Guiana Space Centre|Centre Spatial Guyanais]] (CSG) at [[Kourou]], [[French Guiana]].<ref name="harvey-2003" />{{rp|page=169}} The Ariane 1 soon became considered to be a capable and competitive launcher in comparison to rival platforms offered by the [[Soviet Union]] and the [[United States|United States of America]], and it was quickly followed by improved derivatives in the form of the [[Ariane 2]] and [[Ariane 3]]. By early 1986, the Ariane 1, along with the Ariane 2 and Ariane 3, had become the dominant launcher on the world market.<ref name="harvey-2003" />{{rp|page=172}}

In January 1982, the ESA issued its authorisation for the development and construction of the Ariane 4; the development programme had the stated objective of increasing the usable payload by 90%.<ref name= "encyc aria"/> The Ariane 4 would be a considerably larger and more flexible launcher that the earlier members of its family, being intended to compete with the upper end of launchers worldwide. In comparison, while the Ariane 1 had a typical weight of {{convert|207|t|lb}} and could launch payloads of up to {{convert|1.7|t|lb}} into orbit; the larger Ariane 4 had a typical weight of {{convert|470|t|lb}} and could orbit payloads of up to {{convert|4.2|t|lb}}.<ref name="harvey-2003" />{{rp|page=178}} Work on the Ariane 4 was substantially eased via drawing heavily on both the technology and experiences gained from producing and operating the earlier members of the [[Ariane (rocket family)|Ariane rocket]]. The total development cost for the Ariane 4 was valued at 476 million [[European Currency Unit]]s (ECU) in 1986.<ref name="encyc aria">{{Cite web |editor-last=Wade |editor-first=Mark |title=Ariane |url=http://www.astronautix.com/a/ariane.html |url-status=live |archive-url=https://web.archive.org/web/20240207065823/http://www.astronautix.com/a/ariane.html |archive-date=7 February 2024 |access-date=13 June 2015 |website=Encyclopedia Astronautica }}</ref>

Posed with the requirement to produce a rocket with substantially greater thrust, the design team considered various approaches to achieve this.<ref name="harvey-2003" />{{rp|page=179}} One concept studied had involved the addition of a fifth engine to an enlarged first stage of the Ariane 3, but was found to involve a very high level of redesign work to achieve this; instead, the first stage was elongated to hold {{convert|210|t|lb}} of propellant instead of the {{convert|145|t|lb}} present on the Ariane 3. While the second and third stages remained identical to the Ariane 3, a range of [[Booster (rocketry)|strap-on booster]]s were developed to be applied to the type, designed to gradually increase the rocket's payload capacity.<ref name="harvey-2003" />{{rp|page=179}} Overall, the Ariane 4 was 15% smaller than the Ariane 3.<ref name="harvey-2003" />{{rp|page=180}}

In effect, the Ariane 4 was an improved and developed derivative of the earlier Ariane 3, primarily differing through the application of various [[Solid rocket booster|solid]]-fuelled and [[liquid rocket booster|liquid]]-fuelled boosters, the latter being the only all-new design feature of the Ariane 4; at this point, the practice of using liquid boosters was uncommon, having only previously been used in the [[Chinese space program]].<ref name="harvey-2003" />{{rp|page=179}} Another innovation of the Ariane 4 was the dual-launch SPELDA (Structure Porteuse Externe de Lancement Double Ariane) fairing.<ref name="harvey-2003" />{{rp|page=180}} This had the function of allowing a pair of satellites, one placed on top of the other; several different SPELDA nose fairings could be installed, including normal and extended models. The SPELDA was considerably lighter than its predecessor; the guidance system also used much more accurate [[ring laser gyroscope]]s.<ref name="harvey-2003" />{{rp|page=180}} According to aviation author Brian Harvey, the advances present in the design of the Ariane 4 represented a conservative and evolutionary, rather than revolutionary, philosophy.<ref name="harvey-2003" />{{rp|page=180}}