There are several hundred moons in our solar system, and they are very different. Some have smooth, icy surfaces like Jupiter’s moon Europa, while others, like sulfur-colored Io, can be described as volcanic vents.
But one of the most interesting moons in the solar system is Enceladus. It is much smaller than our Moon and under its relatively smooth surface may be hiding a salty liquid ocean.
This exciting discovery originated from the Cassini space probe in 2005. The probe found geysers pumping water from the surface. These geysers extend several thousand kilometers into the space around Enceladus, which was recently imaged by the James Webb Space Telescope.
But if there is an ocean beneath the surface, is there any chance that the ocean could support life as we know it? A research group has now reported that it has found large amounts of phosphates in dust samples from the Cassini mission.
Researchers believe that the dust originates from the inner ocean on Enceladus. In this case, it would be the first time that vital phosphorus has been found in an ocean on another planet.
The dust was captured by the Cosmic Dust Analyzer instrument on the Cassini space probe. The space probe deliberately crashed into Saturn’s atmosphere in 2017, and now researchers have analyzed measurements from some of those samples.
Phosphorus is a very important element for life as we know it.
The dust comes from Saturn’s so-called E ring, one of the giant planet’s many distinctive rings.
The ghostly ring comes from geysers and icy volcanoes on Enceladus. The ring forms when the ice comes off Enceladus.
But phosphorous isn’t the only element needed to form life as we know it. It is often abbreviated CHNOPS, according to Stephanie Werner. She is a planetary scientist at the University of Oslo and looked at the new research in the journal Nature.
The acronym stands for the elements carbon (C), hydrogen (H), nitrogen (N), oxygen (O), phosphorus (P), and sulfur (S).
Here, phosphorus is absolutely essential, among other things because it is an important part of the energy system that keeps cells alive and because it helps build the structure of DNA itself.
But scientists don’t know if life on other planets necessarily follows the same rules as here on Earth.
In a new research article, the researchers write that they have measured sodium phosphate variables in dust from geysers on Enceladus.
Phosphates are compounds containing phosphorus, hydrogen and oxygen.
Sodium phosphate salts are completely unknown here on Earth, and they have many uses. Among other things, it is used to treat constipation and empty the intestines, According to the Health Directorate.
But that has nothing to do with Enceladus.
Phosphate is the most important source of phosphorus for life as we know it, but not all phosphate is easily absorbed, Werner tells forskning.no.
Phosphorus can come from geological processes that dissolve phosphates in seawater either from the sea floor or from areas around underwater volcanic areas, called hydrothermal stacks. This can be found on the sea floor of Enceladus.
The researchers point to previously published research models of the Moon which state that there may be very little available phosphorous in the sea on Enceladus. They call it the “bottleneck” of these very important elements to life.
Overall, it was previously assumed that phosphorus is probably the least available element of extraterrestrial CHNOPS material, according to the article.
In the new article, the researchers show that there are much higher phosphorus concentrations than previous models of the Moon showed. There are actually concentrations much higher than those in the ocean on land.
So it wasn’t a lack of phosphorus that stopped potential life from developing in the ocean on Enceladus. Stephanie Werner notes that life forms on Earth have evolved ways to extract phosphorus from these available phosphates.
But on Enceladus, this might not be a problem for potential life, because it might already be available and dissolved in ocean waters.
Stephanie Werner points out that Enceladus is a very exciting target for exploration. But it was interesting before phosphorus was discovered in the ocean, too, because of earlier findings from Cassini.
There are still many unanswered questions about the icy moon. Researchers from the University of Berlin, among others, have stated that Enceladus has an ocean that extends around the entire moon under its ice surface.
Werner points out that it is currently uncertain whether this sea extends across the globe and that scientists have worked for many years to interpret the measurements from Cassini. The probe has shown that parts of Enceladus’ surface are quite fresh, which could mean that there is an ocean forming new ice on the underside.
But it does indicate that volcanic ice or the newly formed surface are not evenly distributed around the tiny globe.
It’s been a long time coming for NASA to reach, say, Enceladus. A proposed mission called the Enceladus Orplander, and it could become a priority mission for the space agency, According to Forbes magazine. But that won’t happen until 2050.
Postberg et al: Detection of phosphates originating from the ocean of Enceladus. Nature, 2023. DOI: 10.1038/s41586-023-05987-9. summary
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