We've yet to encounter any Martians on the dry, dusty world next door and it increasingly seems the dark, ice-covered seas of Saturn's moon Enceladus might be a better bet for finding life.
While a frozen shell hides the distant world, it hides a liquid water ocean below that appears to have all the basic requirements for life to survive. New research continues to bolster hopes that although there may be no one floating Martian canals, something might swim the subsurface sea of Enceladus.
Last decade, scientists were thrilled to learn. In the ensuing years, the evidence to support this assessment has continued to pile up.
Before ending its mission by crashing into Saturn, NASA flew its Cassini spacecraft through the frosty plumes of material that shoot out of cracks in Enceladus' shell like a literal space geyser. It picked up high amounts of methane, which is usually associated with life here on Earth.
Now, a new study uses computer modeling to suggest the ocean on Enceladus should also be filled with dissolved phosphorus, which is key to supporting life as we know it.
"What we have learned is that the plume contains almost all the basic requirements of life as we know it," Glein said. "While the bioessential element phosphorus has yet to be identified directly, our team discovered evidence for its availability in the ocean beneath the moon's icy crust," Southwest Research Institute's Christopher Glein, who has been studying Enceladus for years, said in a statement.
A study by Glein and an international team of researchers was published Monday in Proceedings of the National Academy of Sciences.
Running models with data on the ocean-seafloor system on Enceladus, Glein's team predicts there should be as much or more phosphorus than in seawater on Earth.
"What this means for astrobiology is that we can be more confident than before that the ocean of Enceladus is habitable," Glein added.
It was previously thought Enceladus might not have adequate levels of phosphorus to support life. Phosphates in various forms are instrumental in the formation of DNA, RNA, cell membranes and even teeth.
While scientists and astronomers continue to study ocean worlds like Enceladus and Jupiter's moon Europa from afar, Glein cites another important step that needs to be taken as soon as possible: "We need to get back to Enceladus to see if a habitable ocean is actually inhabited."