Sputnik 1 before launch in October 1957

On 4 October 1957, Sputnik 1 was successfully launched and entered Earth's orbit. Thus, began the 'space age'. The launch shocked the world, giving the former Soviet Union the distinction of putting the first human-made object into space. The word 'Sputnik' originally meant 'fellow traveler,' but has become synonymous with 'satellite' in modern Russian.

This historic image shows a technician putting the finishing touches on Sputnik 1, the first artificial satellite. The pressurised sphere made of aluminium alloy had five primary scientific objectives: to test the method of placing an artificial satellite into Earth orbit; to provide information on the density of the atmosphere by calculating its lifetime in orbit; to test radio and optical methods of orbital tracking; determine the effects of radio wave propagation through the atmosphere; and to check principles of pressurisation used in satellites.