Editing Giotto (spacecraft) (section)

==Mission==
===Development===
[[Image:Giotto Halley Grigg-Skjellerup orbit-multi-lang.svg|lang=en|thumb|left|''Giotto'' trajectory]]
Members of the ESA’s Solar System Working Group started investigating a mission to Halley’s comet in 1977 before rejecting it in August 1978 in favour of a lunar orbiter.<ref name=calder21 /> Shortly afterwards this was reversed by the Science Advisory Committee and the ESA started to study a joint mission with NASA.<ref name=calder21>{{cite book |last=Calder |first=Nigel |title=Giotto to the Comets |publisher=Presswork |publication-place=London |date=1992 |isbn=0-9520115-0-6 |pages=21-24}}</ref> This mission was to be the [[International Comet Mission]] consisting of a carrier NASA probe and smaller European probe based on the [[ISEE-2]].<ref name=calder25 /> The plan was for the American probe to release the European probe towards Halley for a close flyby before going on to explore Comet [[10P/Tempel]].<ref name=calder25>{{cite book |last=Calder |first=Nigel |title=Giotto to the Comets |publisher=Presswork |publication-place=London |date=1992 |isbn=0-9520115-0-6 |pages=25-28}}</ref> The NASA probe was cancelled November 1979.<ref name=Hughes>{{cite journal | last=Hughes | first=David W | title=The Giotto-Halley 20th anniversary | journal=Astronomy and Geophysics | volume=47 | issue=1 | date=2006 | issn=1366-8781 | doi=10.1111/j.1468-4004.2006.47127.x | pages=1.27–1.28}}</ref> 

Proposals then moved to an Ariane 1 launched mission with the first option considered being one suggested by [[Giuseppe Colombo]].<ref name=calder31 /> Named HAPPEN it involved using parts for a planned [[GEOS (satellite)|Geos-3]] satellite to first examine the earth's [[Magnetosphere#Magnetotail|Magnetotail]] before flying through the tail of Halley’s comet in march 1986.<ref name=calder31 />  This was rejected 24 January 1980 by the Solar System working group for not offering to return enough information on Halley.<ref name=calder31>{{cite book |last=Calder |first=Nigel |title=Giotto to the comets |publisher=Presswork |publication-place=London |date=1992 |isbn=0-9520115-0-6 |pages=31-32}}</ref> In February 1980 it was proposed that the Ariane 1 launch two Geos based probes.<ref name=calder33 /> One to examine the magnetotail and the other to target Halley’s comet.<ref name=calder33 /> It was at this point the name Giotto name started being used.<ref name=calder33>{{cite book |last=Calder |first=Nigel |title=Giotto to the comets |publisher=Presswork |publication-place=London |date=1992 |isbn=0-9520115-0-6 |pages=33-35}}</ref> The proposal was approved by the Science Advisory Committee and then moved onto the Science program committee.<ref name=calder33 /> The Science program committee initially rejected the mission in favour of the [[Hipparcos]] satellite while giving Giotto at chance for a second submission without the Magnetotail mission but with more extensive planning and a budget of 80 million accounting units.<ref name=calder35>{{cite book |last=Calder |first=Nigel |title=Giotto to the comets |publisher=Presswork |publication-place=London |date=1992 |isbn=0-9520115-0-6 |pages=35-36}}</ref> In July 1980 the committee approved the second proposal with a budget of 80 million accounting units.<ref name=calder38 /> The Hipparcos program, while delayed, also continued.<ref name=calder38>{{cite book |last=Calder |first=Nigel |title=Giotto to the comets |publisher=Presswork |publication-place=London |date=1992 |isbn=0-9520115-0-6 |page=38}}</ref>

During March 1981 British Aerospace submitted its Geos based design to the ESA.<ref name=calder54 /> This was rejected due to issues with power and temperature control.<ref name=calder54 /> In the same period it was found that the Geos design had become outdated to the point where it was no longer possible to obtain parts.<ref name=calder54 /> As a result a new and somewhat larger craft was designed although British Aerospace remained the primary contractor.<ref name=calder54>{{cite book |last=Calder |first=Nigel |title=Giotto to the comets |publisher=Presswork |publication-place=London |date=1992 |isbn=0-9520115-0-6 |pages=54-57}}</ref>

Originally it was planned to launch Giotto on an [[Ariane 2]] along with a commercial satellite.<ref name=calder65 /><ref name=calder33 /> This was then shifted to an [[Ariane 3]] before difficulties with finding a customer who wanted to fly during the launch window resulted in Giotto being assigned solo to an Ariane 1 which was available after [[EXOSAT]] was launched by a [[Thor-Delta]].<ref name=Dickson>{{cite journal |last=Dickson |first=David |title=Ariane Loses One to NASA |journal=Science |volume=219 |issue=4589 |date=11 March 1983 |issn=0036-8075 |doi=10.1126/science.219.4589.1202 |page=1202}}</ref><ref name=calder65>{{cite book |last=Calder |first=Nigel |title=Giotto to the Comets |publisher=Presswork |publication-place=London |date=1992 |isbn=0-9520115-0-6 |page=65}}</ref>

There were plans to have observation equipment on board a [[Space Shuttle]] in low-Earth orbit around the time of ''Giotto''{{'}}s fly-by, but they in turn fell through with the [[STS-51-L|''Challenger'' disaster]].

The plan then became a cooperative armada of five space probes including ''Giotto'', two from the [[Soviet Union]]'s [[Vega program]] and two from Japan: the ''[[Sakigake]]'' and [[Suisei (spacecraft)|''Suisei'']] probes. The idea was for Japanese probes and the pre-existing American probe [[International Cometary Explorer]] to make long distance measurements, followed by the Soviet Vegas which would locate the nucleus, and the resulting information sent back would allow ''Giotto'' to precisely target very close to the nucleus. Because ''Giotto'' would pass so very close to the nucleus ESA was mostly convinced it would not survive the encounter due to the spacecraft colliding at very high speed with the many dust particles from the comet. The coordinated group of probes became known as the [[Halley Armada]].