Search for life beyond Earth might only need go as far as Saturn's rings
CAPE CANAVERAL, Florida — Scientists might have found signs of life buried in the rings of Saturn.
The candidate: A tiny, ice-encrusted ocean world orbiting Saturn's moon called Enceladus.
NASA's Cassini spacecraft has found hydrogen molecules in the geysers shooting off Enceladus, scientists announced last week. They think these molecules could be coming from chemical reactions deep in the ocean. These reactions between water and rock could spark life for microbes—that is, microscopic living creatures.
We should hold our expectations, though, NASA and others say. The latest discovery does not mean there is life on Enceladus. It just means that the moon of Saturn has conditions that could sustain life as we know it.
Where There's Hydrogen
A liquid ocean exists beneath the icy surface of Enceladus, which is barely 300 miles across. Clouds of water vapor spray from the cracks on the south pole of the moon. Scientists have long known about this, thanks to closer study by the Cassini spacecraft.
When scientists find a lot of hydrogen, it is a good sign for life. It means there could be chemical reactions happening between the warm water and ocean-floor rock that could support life.
Cassini uncovered the hydrogen during its final close flyby of Enceladus in 2015. It searched deeper through the moon's clouds of vapor and particles. The researchers reported finding hydrogen and carbon dioxide. This combination could mean that undersea microbes are producing methane gas. This is what microbes do deep below Earth's oceans and waterways.
Science Fans Worldwide Were Excited
It is a very special finding for the mission, said Cassini's project scientist, Linda Spilker. The spacecraft has been circling Saturn for more than a decade.
"We now know that Enceladus has almost all of the ingredients that you would need to support life as we know it on Earth," she said at a NASA news conference.
Science fans around the world watched the press conference online and asked the scientists questions via Twitter. One viewer asked NASA about the type of life Enceladus might have. Could it be a bacteria or slimy green algae — or even giant squids?
"Most of us would be excited with any life," said Mary Voytek, an astrobiology senior scientist for NASA. "We're going to start with bacteria and, if we get lucky, maybe there's something that's larger."
Spacecraft Is Nearing Its Demise
The findings were reported in the journal Science by a team of scientists from Southwest Research Institute in San Antonio, Texas.
Launched in 1997 and now finally running low on fuel, Cassini is drawing ever closer to its final days. The spacecraft will duck through the gap between Saturn and its rings 22 more times. Then, this September, it will start spiraling out of control and fall apart in the sky above Saturn.
Cassini has no instruments that can detect life on new worlds. It will be up to future robotic visitors to seek out possible life on Enceladus, the scientists said.
Future Missions Will Gather More Information
Europa, an ice-covered moon of Jupiter also believed to have a subsurface ocean, might have water vapor jets spewing into space as well, similar to Enceladus. The Hubble Space Telescope has seen what looks to be vapor jets bubbling on Europa.
A spacecraft under development called the Europa Clipper, set to launch sometime in the 2020s, could give more details on this moon's landscape.
Voytek said her bet is still on Europa for potential life, versus Enceladus. Europa is much older and any potential life there has had more time to emerge.
While questions remain, the news represents "an important advance" in determining if humans or other creatures could live on Enceladus, Jeffrey Seewald said in a different article. He is an ocean scientist working for the Woods Hole Oceanographic Institution.
"We still have a long way to go in our understanding," said Seewald, who was not involved in the study. "Future missions to explore oceans beyond Earth will answer many of these questions."