Five geckos who were tasked with reproducing in zero gravity on a Russian research satellite did not survive the mission, Russia's space agency said.
The now-famous sex lizards, one male and four female, were found dead when the Foton M4 satellite returned to earth on Monday.
The sad news comes after a tumultuous trip for the research satellite, during which mission control lost control of the satellite for a week shortly after it was launched on July 19.
Russia again lost control of the satellite briefly last week, and the decision was made to prematurely abort the mission before the full 60 days were completed, according to Interfax.
The geckos are believed to have lost their lives within the last week and ITAR-TASS news agency reported that they were found "partly mummified."
“Hypothermia is not the main possible cause but only one of the options. Others include a possible malfunction of the on board equipment and life-support system,” a space industry source told ITAR-TASS.
But Sergei Savelyev, the lead researcher for the experiment said that the geckos died within hours of each other a few days before it landed back on earth, according to the Moscow Times. Savelyev added that the geckos were unlikely to have been mummified and deaths were more likely a result of the failure of life support systems.
An autopsy will be conducted by the end of Tuesday he added.
Russian officials initially said they believed that the experiments were still going as planned after the first loss of communication with the satellite. Several other organisms, including fruit flies, silkworm eggs, dried seeds and mushrooms were sent up into Earth's outer atmosphere to observe how they survived in the extraterrestrial environment.
There is some good news, however. The fruit flies are doing just fine, Russia's Federal Space Agency said. They grew and multiplied, as planned.
[This post has been updated.]