Sputnik 1: the first artificial signal from Earth orbit

Sputnik 1 was a satellite about 58 centimetres across and weighing 83.6 kilograms, with four long antennas. Radio transmitters and batteries were protected inside a sealed spherical shell. The mission placed this compact apparatus in Earth orbit.

The Soviet satellite programme was connected with research during the 1957–1958 International Geophysical Year. Its launcher had to accelerate the payload sufficiently for continued orbital motion.

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A Soviet launch vehicle placed Sputnik 1 in an elliptical Earth orbit on October 4, 1957. The satellite circled the planet in about 98 minutes and transmitted recurring radio pulses, detectable by receivers on the ground.

It was the first artificial satellite to reach Earth orbit. A manufactured object had acquired orbital velocity and repeatedly passed over the planet.

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TASS announced the flight, and Pravda published the communiqué on October 5. It described the sphere’s dimensions, mass, radio equipment and orbit, carrying news of the launch and flight to a wider public.

The transmitted signals supported tracking. Receivers in different locations and orbital calculations allowed its position to be checked, turning the announcement into a detectable and measurable phenomenon.

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The flight joined rocketry, radio and orbital measurement. Later satellites measured space, photographed Earth and relayed information, developing long-duration power, precise control and varied payloads.

Sputnik also intensified Soviet and American space programmes. Devices operating beyond Earth became part of human activity, with ground stations and orbiting payloads forming a new working system.

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