On Ocober 4, 1957, the Soviet Union rocked the world, and rocketed out of the world, with the launch of the first Earth-orbiting satellite, Sputnik 1. From now on there would be two races, in arms and in space, which would be intimately linked. American pride and morale demanded a swift reply. It came on January 31, 1958, with the launch by a Jupiter-C booster of the Explorer 1 satellite. Suddenly, the possibility of traveling to the planets and, eventually, even to the stars seemed more real – as, too, did the possibility that other beings might have visited Earth.