The successful launches of Explorer and Vanguard boosted American morale, but not for long. In May 1958 the Soviet Union launched Sputnik 3, an instrument-packed satellite weighing a massive 1.3 tonnes (Explorer and Vanguard weighed 14 kg and 1.5 kg respectively).
It was clear that the Soviets had powerful launch vehicles, and were preparing to launch a man into orbit. In May 1960 they launched the 4.5 tonne Sputnik 4. This was a dress rehearsal for a manned space flight. Sputnik 4 went into orbit without a hitch, but when its retro-rockets were fired to slow it down so that it could return to Earth, it was facing the wrong way, and instead of coming down, the spacecraft went into a higher orbit. It remained in orbit for five months before eventually burning up in the atmosphere.
Sputnik 5, launched on 19 August, 1960 met with spectacular success. It carried two dogs, Belka (Squirrel) and Strelka (Little Arrow). The capsule was brought down the next day, and the dogs became celebrities as the first living things to return from orbit. However, the Soviets could not duplicate this success in Sputnik 6, which was launched on December 1, 1960. It re-entered the atmosphere at too steep an angle, after a day in orbit, and burned up. Unfortunately this spacecraft too carried two dogs, which, of course, perished.
The last Sputnik was launched on March 25, 1961. It carried the dog, Zvezdochka (Little Star) and a dummy cosmonaut on a one-orbit trip. Both the spacecraft and its passenger returned safely.
Man’s best friend had shown the way, now it only remained for the man to follow.