The five geckos on the Foton-M4 - four female and one male - were launched into space for a 60-day flight to find out about the effects of weightlessness on the creatures' sex lives.

The five geckos on the Foton-M4 - four female and one male - were launched into space for a 60-day flight to find out about the effects of weightlessness on the creatures' sex lives. AP Photo - NASA, Bill Ingalls

RUSSIAN scientists have lost contact with an experimental satellite filled with geckos that was to be the focus of new research on animal sex in the weightlessness of orbit.

The Foton-M4 spacecraft was launched from Kazakhstan's Baikonur Cosmodrome on 19 July and made several orbits of the planet before it stopped responding to commands from Roscosmos, Russia's Federal Space Agency.

"So, there is only one-way communication," a spokesperson for mission control was quoted as saying by news agency ITAR-Tass, adding that engineers were looking to fix the problem in case life systems were disrupted, killing the creatures on board.

The five geckos on the Foton-M4 - four female and one male - were launched into space for a 60-day flight to find out about the effects of weightlessness on the creatures' sex lives.

A Madagascar day gecko sits on a perch. Image: Reuters

Oleg Voloshin, a spokesperson for the company running the experiment, confirmed that this part of the mission has already begun and that other experiments on board - including a project to grow pure crystals to be used in advanced semi-conductors - were also in working order.

The satellite is the latest in the Russian Foton-M series to be launched into space. The first launch in 2001 failed, tragically falling back to Earth and killing 20-year-old soldier Ivan Marchenko, while the second successfully proved in 2004 the lichen could survive in space for 14 days.

The third Foton-M craft was launched in 2007 and provided a temporary home to geckos, newts, snails and Mongolian gerbils. The satellite spent 12 days in orbit before safely returning to Earth, with a study of the creatures noting that the gerbils had "moved chaotically" in space.

Landing of the Foton-M4 was originally scheduled for September, although scientists will have to regain control of the craft if it is to be safely landed in southern Russia.