This historic image shows a technician putting the finishing touches on Sputnik 1, humanity's first artificial satellite.
Image Credit: NASA/Asif A. Siddiqi

On this day in 1957, (October 4th), Sputnik 1 successfully launched and entered orbit around Earth, beginning the famed “space race”. Sputnik’s lanuch by the former Soviet Union shocked the world by putting the first man-made object in space. Of note, in Russian, ‘Sputnik’ originally meant ‘fellow traveler,’ but in modern Russian is has become a synonym for ‘satellite’.

As shown in the image above, Sputnik was comprised of a pressurized sphere made of aluminum alloy. There were five primary scientific objectives for the Sputnik mission: Test the method of placing an artificial satellite into Earth orbit; provide information on the density of the atmosphere by calculating its lifetime in orbit; test radio and optical methods of orbital tracking; determine the effects of radio wave propagation though the atmosphere; and, check principles of pressurization used on the satellites.

Source:NASA Image of the Day Galley