Thor-Able Star with the Transit IV satellite.
Fifty years ago, the US Air Force launched yet another Thor rocket, but this one had a different second stage, Ablestar. The new stage allowed a heavier payload, which in this case included three different satellites! Transit IV-A was the predecessor of today's navigation satellites, and was powered by nuclear elements, making it the first satellite to be nuclear-powered. The second and third satellites were the Injun (gathering data on radiation belts around the Earth) and Greb III (gathering data on X-rays from the Sun). The satellites were successfully launched from the LC-17 pad at the Atlantic Missile Range at Cape Canaveral, Florida.