I have some thoughts about space anniversaries, over at Pajamas Media.
[Update a few minutes later]
Alan Boyle has a more detailed and humanized history of the Explorer 1 mission. Though I should add, as I say in my own piece, that the belts weren't "discovered" by the satellite--their theoretical existence had previously been proposed by Christofilos, so finding them was confirmation, rather than a complete surprise.
And of course, let's not forget that the US satellite would have been first, were it not for bureaucratic turf wars between the US Army and the US Navy.
Were it not for that; no panic when the Russians were first, no injured American pride, no headlong race for the Moon; and space would have been explored as it should have been and everyone before the Space Age assumed it would be - by small and careful steps, with the building of infrastructure and methods of actually working in space.
And by now we'd have had a working Moonbase, and probably space colonisation at a reasonable scale, and SPS, and less dependence on unstable 8th century theocracies for essential goods; and maybe there would be a few people who didn't call Earth home.
But it didn't happen that way - because of bureaucratic empire building; and because of all that, perhaps a billion people will die after an American city goes up in smoke.
I hope those generals and admirals are proud of themselves, wherever they are now.