This satellite was identical to the previous one which crashed a couple weeks earlier, having been built beforehand as a backup. The Sputnik rocket was programmed to throttle back at T+85 seconds, right before the last anomaly occurred, in the hopes that it would reduce structural loads. It appeared to have worked as it made it successfully to orbit, but the vibrations still occurred to a lesser degree.

Sputnik 3 was an automatic scientific laboratory spacecraft. It was conically shaped and was 3.57 m long and 1.73 m wide at its base. It weighed 1,327 kg and carried twelve scientific instrumentation. After 692 days in orbit, Sputnik 3 reentered the atmosphere and burned up on 6 April 1960. It was powered by silver-zinc batteries and silicon solar cells which operated for approximately 6 weeks.