A Russian capsule carrying 45 mice and 15 newts has returned from a month's mission in orbit with data scientists hope will pave the way for a manned flight to Mars.
Russian Mission Control said the Bion-M craft landed softly on Sunday with the help of a special parachute system in the Orenburg Region about 1200 kilometres southeast of Moscow.
The capsule was also carrying snails and gerbils as well as some plants and microflora, AFP reports.
There was no immediate information about how many of the animals survived.
A field research lab has been deployed near where the capsule landed to quickly test the animals' response to their journey and return to Earth.
Scientists said the animals were needed because they were subject to the kinds of experiments not able to conducted on humans who are currently operating the International Space Station (ISS).
They added the small menagerie would have posed a health risk if simply placed on board the ISS for a month.
The experiment's designers said the tests primarily focused on how microgravity impacts the skeletal and nervous systems as well organisms' muscles and hearts.
The capsule spun 575 kilometres above Earth.
Russia has long set its sights on Mars and is now targeting 2030 as the year in which it could begin creating a base on the Moon for flights to the Red Planet.
But recent problems with its once-vaunted space programme - including the embarrassing failure of a research satellite Moscow tried sending up to one of Mars' moons last year - have threatened Russia's future exploration efforts.