America's First Satellite
Better Late Than Never
After the launches of Sputnik and Sputnik II,
the first American satellite needed to demonstrate its significance in order to
compete with its Soviet rivals. That significance was scientific discovery.
I, while small, contained two key scientific instruments: A
micrometeoroid impact detector and a cosmic ray detector. These were installed
on top of the Juno I rocket in a
tub that rotated at 720 rotations per minute. The spinning kept the satellite
stable after it separated from the rest of the rocket. This was essential
because the satellite could not carry fuel or engines to stabilize itself. The
Explorer I satellite confirmed the existence of bands of radiation around the
Earth, now known as the Van Allen Radiation Belts, and recorded 145 impacts of
cosmic dust over 12 days.