Editing Explorer 1 (section)

== Background ==
The U.S. Earth satellite program began in 1954 as a joint U.S. Army and U.S. Navy proposal, called Project Orbiter, to put a scientific satellite into orbit during the [[International Geophysical Year]]. The proposal, using a military Redstone missile, was rejected in 1955 by the Eisenhower administration in favor of the Navy's [[Project Vanguard]], using a booster advertised as more civilian in nature.<ref>Matt Bille and Erika Lishock, The First Space Race: Launching the World's First Satellites, Texas A&M University Press, 2004, Chapter 5.</ref><ref name="time">{{cite magazine |url=http://www.time.com/time/magazine/article/0,9171,937919-1,00.html |archive-url=https://web.archive.org/web/20080515162755/http://www.time.com/time/magazine/article/0,9171,937919-1,00.html |archive-date=15 May 2008 |title=Project Vanguard – Why It Failed to Live Up to Its Name |access-date=30 July 2024 |date=21 October 1957 |magazine=[[Time (magazine)|Time]]}}</ref> Following the launch of the Soviet satellite Sputnik 1 on 4 October 1957, the initial [[Project Orbiter]] program was revived as the Explorer program to catch up with the Soviet Union.<ref name="space age">{{cite web |url=https://history.nasa.gov/sputnik/ |title=Sputnik and the Dawn of the Space Age |work=NASA History |publisher=NASA |date=2 February 2005 |access-date=30 July 2024}} {{PD-notice}}</ref>

Explorer 1 was designed and built by the [[Jet Propulsion Laboratory]] (JPL), while a [[Jupiter-C]] rocket was modified by the [[Army Ballistic Missile Agency]] (ABMA) to accommodate a satellite payload; the resulting rocket known as the Juno I. The Jupiter-C design used for the launch had already been flight-tested in nose cone reentry tests for the [[PGM-19 Jupiter|Jupiter]] [[intermediate-range ballistic missile]] (IRBM) and was modified into Juno I. Working closely together, ABMA and JPL completed the job of modifying the Jupiter-C and building Explorer 1 in 84 days. However, before work was completed, the Soviet Union launched a second satellite, [[Sputnik 2]], on 3 November 1957. The [[U.S. Navy]] attempted to put the first U.S. satellite into orbit but failed with the launch of the [[Vanguard TV-3]] on 6 December 1957.<ref>{{cite web |url=http://www.hq.nasa.gov/office/pao/History/SP-4202/cover.htm |title=Chapter 11: from Sputnik I to TV-3 |access-date=7 October 2018 |last=McLaughlin Green |first=Constance |author2=Lomask, Milton |year=1970 |work=Vanguard, A History |publisher=NASA |archive-date=7 October 2018 |archive-url=https://web.archive.org/web/20181007015322/https://www.hq.nasa.gov/office/pao/History/SP-4202/cover.htm}} {{PD-notice}}</ref>