Phosphorus, although rare on Earth’s surface, may be abundant on other worlds
The last key component of life has been discovered on Saturn’s icy moon Enceladus.
Phosphorus is a vital building block of life, used to build DNA and RNA. Now, analysis of data from NASA’s Cassini spacecraft shows that Enceladus’ subsurface ocean contains an important nutrient . Moreover, its concentration there can be thousands of times greater than in the Earth’s ocean, planetary scientist Yasuhito Sekine reported on December 14 at the fall meeting of the American Geophysical Union.
According to Sekine of the Tokyo Institute of Technology, the important element may also be abundant on many other icy worlds, promising the search for alien life.
“We knew that Enceladus contains most of the elements necessary for life as we know it — carbon, hydrogen, nitrogen, oxygen and sulfur,” says Morgan Cable, an astrobiologist at the Jet Propulsion Laboratory in Pasadena, California. does not participate in the study. “Now that [фосфор] has been confirmed … Enceladus now appears to meet all the criteria for a habitable ocean.”
Many researchers consider Enceladus to be one of the most likely places to find extraterrestrial life. It is a world covered in ice, hidden beneath an ocean of salt water. Moreover, in 2005 the Cassini spacecraft watched the geysers eject steam and grains of ice from the icy shell of Enceladus. And in this space spray, scientists discovered organic molecules .
But until now, researchers weren’t sure if phosphorus existed on Enceladus. The element is relatively rare on the Earth’s surface. Most phosphorus is concentrated in minerals, and its presence often determines the rate at which life reproduces.
So Sekine and his colleagues analyzed chemical data collected by the now-defunct Cassini spacecraft on particles in Saturn’s E ring, a halo of material ejected from the jets of Enceladus that orbits Saturn.
The researchers found that some of the ice grains in ring E are enriched with a phosphorus compound called sodium phosphate. They estimate that a kilogram of water from Enceladus’ ocean contains about 1 to 20 millimoles of phosphate, a concentration thousands of times greater than in Earth’s great blue ocean.
At the bottom of Enceladus’ subsurface ocean, phosphate may form from a reaction between seawater and a phosphate-containing mineral called apatite, Sekin said, before being ejected by geysers into space. Apatite is often found in carbonaceous chondrites primitive material for building a planet.
The past is prologue
But that’s not all. Many other icy ocean worlds may also contain apatite, Sekin said. Similarly, they can also carry high levels of phosphates in their oceans. This wealth could be a boon to any potential alien organisms.
While the results are promising, they raise a glaring conundrum, Sekin said. “If [на] Enceladus has life, why [залишається] like that [] large amounts of chemical energy and nutrients?’ After all, here on Earth, any available phosphorus is quickly absorbed by life.
It is possible that there is simply no life on the moon, Sekin said. But there is another more hopeful explanation. According to him, life on cold Enceladus may simply consume nutrients slowly.
