Sputnik 1

A polished aluminium sphere, 58 centimetres across and 83.6 kilograms, was what the Soviet Union placed into orbit on 4 October 1957 at 22:28 Moscow time.

It carried no instruments beyond internal temperature sensors and two radio transmitters broadcasting on 20.005 and 40.002 MHz — frequencies any shortwave receiver in the world could detect.

The vehicle was a modified R-7 intercontinental ballistic missile, launched from Pad 1/5 at Baikonur, and the orbit it achieved — perigee 215 km, apogee 939 km — was elliptical, inclined 65 degrees, and entirely unexpected by most of the world.

For twenty-two days, until the batteries expired, the sphere beeped. It completed approximately 1,440 orbits before re-entering the atmosphere on 4 January 1958.