The Russian space agency announced that all five of the geckos sent into space for the purposes of sexual experiments have died. The scientific casualties were discovered when the Foton-M4 satellite carrying the geckos returned to Earth on Monday. The geckos were part of a study to evaluate the effect of weightlessness on sex lives and development. An expert working on the mission told Interfax that the geckos appeared to have frozen to death after a heating-system malfunction. However, the Russian space agency has yet to state an official cause of death. “We can say with confidence that they died at least a week before the landing because their bodies were partly mummified,” said an official from Russia’s Institute of Medical and Biological Problems.