What was the approximate launch mass of Sputnik 1, the first artificial satellite?

Sputnik 1 had a launch mass of approximately 83.6 kilograms.

The Soviet Union launched Sputnik 1 on October 4, 1957, from Baikonur Cosmodrome aboard a modified R-7 rocket. The polished spherical satellite measured about 58 centimeters across and carried four external whip antennas for transmitting radio signals.

Its mass was modest compared with later spacecraft, but the satellite had enormous political and scientific importance. Its regular radio beeps could be detected around the world, demonstrating that the Soviet Union had successfully placed an artificial object in orbit and could build powerful rockets capable of reaching space.

Sputnik 1 orbited Earth for about three months before atmospheric drag caused it to reenter on January 4, 1958. It is often confused with Sputnik 2, which was larger and carried the dog Laika. Sputnik 1 carried no living passenger; its instruments measured temperature and pressure and monitored its power systems.