Editing Galileo project (section)

===Nuclear concerns===
As the launch date of ''Galileo'' neared, [[Anti-nuclear movement in the United States|anti-nuclear groups]], concerned over what they perceived as an unacceptable risk to the public's safety from the [[plutonium]] in ''Galileo''{{'}}s GPHS-RTG modules, sought a court injunction prohibiting ''Galileo''{{'s}} launch.<ref name="Groups Protest Use of Plutonium">{{cite news |newspaper=[[The New York Times]] |title=Groups Protest Use of Plutonium on Galileo |first=William J. |last=Broad |author-link=William Broad |date=October 10, 1989 |url=https://www.nytimes.com/1989/10/10/science/groups-protest-use-of-plutonium-on-galileo.html |access-date=November 4, 2020 |archive-date=February 12, 2021 |archive-url=https://web.archive.org/web/20210212025607/http://www.nytimes.com/1989/10/10/science/groups-protest-use-of-plutonium-on-galileo.html |url-status=live }}</ref> RTGs were necessary for deep space probes because they had to fly distances from the Sun that made the use of solar energy impractical.<ref name="Sagan" /> They had been used for years in planetary exploration without mishap: the Department of Defense's [[Lincoln Experimental Satellite]]s 8/9 had 7 percent more plutonium on board than ''Galileo'', and the two [[Voyager program|''Voyager'' spacecraft]] each carried 80 percent of ''Galileo''{{'s}} load of plutonium.<ref name="RTG">{{cite web |title=What's in an RTG? |publisher=NASA/Jet Propulsion Laboratory |url=http://www2.jpl.nasa.gov/galileo/messenger/oldmess/RTG.html |access-date=May 15, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20100411024748/http://www2.jpl.nasa.gov/galileo/messenger/oldmess/RTG.html |archive-date=April 11, 2010 }}</ref> By 1989, plutonium had been used in 22 spacecraft.<ref>{{cite magazine |title=Plutonium gets a lift from Galileo |magazine=[[New Scientist]] |issn=0262-4079 |url=https://www.newscientist.com/article/mg12216683-100-plutonium-gets-a-lift-from-galileo/ |date=June 10, 1989 |access-date=November 4, 2020 |archive-date=October 28, 2020 |archive-url=https://web.archive.org/web/20201028151529/https://www.newscientist.com/article/mg12216683-100-plutonium-gets-a-lift-from-galileo/ |url-status=live }}</ref>

Activists remembered the crash of the [[Soviet Union]]'s nuclear-powered [[Kosmos 954]] satellite in Canada in 1978, and the ''Challenger'' disaster, while it did not involve nuclear fuel, raised public awareness about spacecraft failures. No RTGs had ever done a non-orbital swing past the Earth at close range and high speed, as ''Galileo''{{'s}} VEEGA trajectory required it to do. This created the possibility of a mission failure in which Galileo struck Earth's atmosphere and dispersed plutonium. [[Planetary scientist]] [[Carl Sagan]], a strong supporter of the ''Galileo'' mission, wrote that "there is nothing absurd about either side of this argument."<ref name="Sagan">{{cite web |last=Sagan |first=Carl |author-link=Carl Sagan |title=Galileo: To Launch or not to Launch? |date=October 9, 1989 |url=http://www.dartmouth.edu/~chance/course/Syllabi/97Dartmouth/day-6/sagan.html |access-date=November 4, 2020 |archive-date=January 26, 2021 |archive-url=https://web.archive.org/web/20210126152333/http://www.dartmouth.edu/~chance/course/Syllabi/97Dartmouth/day-6/sagan.html |url-status=dead }}</ref>

Before the ''Challenger'' disaster, JPL had conducted shock tests on the RTGs that indicated that they could withstand a pressure of {{convert|2,000|psi|order=flip}} without a failure, which would have been sufficient to withstand an explosion on the launch pad. The possibility of adding additional shielding was considered but rejected, mainly because it would add an unacceptable amount of extra weight.{{sfn|Meltzer|2007|p=77}} After the ''Challenger'' disaster, NASA commissioned a study on the possible effects if such an event occurred with ''Galileo'' on board. Angus McRonald, a JPL engineer, concluded that what would happen would depend on the altitude at which the Space Shuttle broke up. If the ''Galileo''/IUS combination fell free from the orbiter at {{convert|90000|ft|order=flip|sp=us}}, the RTGs would fall to Earth without melting, and drop into the Atlantic Ocean about {{convert|150|mi|order=flip|sp=us}} from the Florida coast. On the other hand, if the orbiter broke up at an altitude of {{convert|323,800|feet|order=flip|sp=us}} it would be traveling at {{convert|7957|ft/s|order=flip|sp=us}} and the RTG cases and GPHS modules would melt before falling into the Atlantic {{convert|400|mi|order=flip|sp=us}} off the Florida coast.<ref>{{cite magazine |last=Portree |first=David S. F. |title=If Galileo Had Fallen to Earth (1988) |date=December 18, 2012 |magazine=[[Wired (magazine)|Wired]] |issn=1059-1028 |url=https://www.wired.com/2012/12/galileo-and-an-uncontrolled-shuttle-orbiter-reentry-1988/ |access-date=November 4, 2020 |archive-date=October 27, 2020 |archive-url=https://web.archive.org/web/20201027072205/https://www.wired.com/2012/12/galileo-and-an-uncontrolled-shuttle-orbiter-reentry-1988/ |url-status=live }}</ref><ref>{{cite report |title=Galileo: Uncontrolled STS Orbiter Reentry |id=JPL D-4896 |first=Angus D. |last=McRonald |publisher=NASA |date=April 15, 1988 |url=https://www.nasa.gov/pdf/24889main_JPL_Report.pdf |access-date=November 4, 2020 |archive-url=https://web.archive.org/web/20221111183533/https://www.nasa.gov/pdf/24889main_JPL_Report.pdf |archive-date=11 November 2022 }}</ref>

NASA concluded that the chance of a disaster was 1 in 2,500, although anti-nuclear groups thought it might be as high as 1 in 430.<ref name="Groups Protest Use of Plutonium" />{{sfn|Office of Space Science and Applications|1989|p=2-23}} NASA assessed the risk to an individual at 1 in 100 million, about two orders of magnitude less than the danger of being killed by lightning.{{sfn|Office of Space Science and Applications|1989|p=2{{hyphen}}24}} The prospect of an inadvertent re-entry into the atmosphere during the VEEGA maneuvers was reckoned at less than 1 in 2 million,<ref name="RTG"/> but an accident might have released a maximum of {{convert|11,568|Ci|lk=on}}. This could result in up to 9 fatalities from cancer per 10 million exposed people.{{sfn|Office of Space Science and Applications|1989|pp=2{{hyphen}}21, 4{{hyphen}}18}}