Explorer 1 atop a Jupiter-C in gantry. Jupiter-C carrying the first American satellite, Explorer 1, was successfully launched on January 31, 1958. The Jupiter-C launch vehicle consisted of a modified version of the Redstone rocket's first stage and two upper stages of clustered Baby Sergeant rockets developed by the Jet Propulsion Laboratory and later designated as Juno boosters for space launches
1958-01-31
NASA: <a rel="nofollow" class="external text" href="http://mix.msfc.nasa.gov/abstracts.php?p=876">Jupiter C/Explorer 1 in Gantry</a> – MSFC Negative Number: 6414025 – Reference Number: MSFC-75-SA-4105-2C