The Sputnik 5 reference article from the English Wikipedia on 24-Jul-2004
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Sputnik 5

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Sputnik 5 (also sometimes called Korabl-Sputnik 2) was the first satellite to return animals from orbit. It was launched on August 19 1960, and was in fact the second test flight of the Vostok spacecraft. The two dogs Strelka and Belka returned safely to earth after 18 orbits.

See also: Sputnik program