A Russian capsule carrying mice and lizards has returned to Earth after spending a month in space.

Scientists say the experiment is intended to test the effects of weightlessness and other factors of space flight on cell structure.

Russian state television showed the capsule and some of its inhabitants after it landed safely Sunday in a planted field near Orenburg, about 1,200 kilometers (750 miles) southeast of Moscow. The report said not all of the animals survived the flight.

Vladimir Sychov, deputy director of the Institute of Medical and Biological Problems, said it was the first time that animals had spent so much time in space on their own.

The mice and lizards were to be flown back to Moscow to undergo a series of tests at the institute.