We know little about Laika, the first space explorer; most likely she was a stray dog grabbed from a Moscow street and hurriedly trained at the Institute of Aviation and Space Medicine for her historic mission.

She was called Kudryavka when she barked on Radio Moscow on October 25, 1957, just after Soviet leader Nikita Khrushchev announced news of her upcoming launch. Once she was launched into space on November 3, the Soviets renamed her "Laika," Russian for "barker" - while the Americans added the nickname "Muttnik." She was also known as Limonchik (little lemon) and Zhuchka (little bug).

We know Laika was female; the Soviets used only females dogs in early space missions (they needed less room to relieve themselves). She has been (mis)identified as Samoyed husky, beagle, and terrier - but was most likely a mongrel. She was small, only 13 lbs. (6 kg.) and about three years old when she was launched into sudden global prominence aboard Sputnik 2, where she lasted from a few hours to a week and a half, depending on which account you read.

Laika was the only animal or human ever sent into space without a recovery plan. Many years later, Laika's trainer Oleg Gazenko, expressed his remorse: "the more time passes, the more sorry I've become…we did not learn enough from the mission to justify the death of the dog."