Today is the 50th anniversary of the launch of Sputnik, the Soviet satellite which was the first man-made object to be sent into an Earth orbit.
The successful launch was announced obliquely in a small news item on the front page of Pravda, but immediately became front page news around the world.
Sputnik was a small silver-coloured ball 58cm (2 feet) in diameter, with four frond-like antennae and two radio transmitters.
Radio stations rushed to record and re-broadcast the crackly 'beep-beep' signal emitted by the satellite, and it became an iconic sound for a new era – the space generation.
Transmission continued for three weeks until the batteries failed, and Sputnik itself completed 1,400 orbits in three months before it was seen to begin to fall back to earth.
The US was highly embarrassed by the technological superiority of the Soviet Union indicated by the launch, and that of Sputnik 2 a month later, with a dog named Laika on board.
To add to the humiliation, the launches were announced as part of the Soviet Union's contribution to the International Geophysical Year (1957-1958).
NASA hastily scheduled a launch for the following December.
It was to be the third test firing of the Vanguard rocket, to launch a Vanguard-1 satellite similar to but less than one-third the size of Sputnik, but it failed dramatically, rising only just over a metre before falling back and exploding.
