A Russian space capsule carrying mice, gerbils and other animals returned from a month in space Sunday — most of them dead.
Less than half of the 45 mice, eight gerbils and 15 newts survived the flight in the Baikonur Cosmodrome, which was designed to test how extended periods of time in space might affect astronauts, Russian news agencies reported.
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Still, scientists hope the data gathered will help pave the way to a manned flight to Mars.
According to Russian scientists, the animals on board the Bion-M craft died because of equipment failure or from the stresses of space.
The craft itself landed softly early on Sunday with the help of a special parachute system in the Orenburg region about 750 miles southeast of Moscow.
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Snails, some plants and microflora were also on board.
A space pioneer, Russia is no newbie to animal-centered space expeditions.
The Soviets sent dogs into space in the early 1950s, but this latest endeavor was one of the longest of its kind.
The last research craft to carry animals into space spent 12 days in orbit in 2007.
AFP contributed to this report.