It has been hailed as one of the most likely places for extraterrestrials to exist in our solar system.
But unfortunately, a new study casts doubt that Europa, Jupiter’s fourth largest moon, has the right conditions for life.
Researchers at Princeton University have discovered that there is less oxygen on the moon’s surface than previously thought, which is crucial for cell functioning.
While not completely ruling out the possibility of life on Europa, the study says there is a “narrower range to support habitability” than we thought.
The news will be a blow to space fans who have hopes for Europa, which is one of the few places in our solar system with liquid water.
Europa is made up of an ice sheet, whose thickness is estimated at about 24 kilometers and a very thin atmosphere. Shown here, imaged by the Juno spacecraft, September 2022.
Scientists are almost certain that hidden beneath Europa’s icy surface is a saltwater ocean with about twice as much water as Earth’s global ocean. The illustration shows a possible model of Europe.
Dr. Jamey R. Szalay, who led the study, said: “Unless Europe’s oxygen production was significantly higher in the past, the O2 production rates found here…provide a narrower range to support habitability than previous model-based estimates.
Slightly smaller than Earth’s moon, Europa is composed of a shell of ice, estimated to be 10 to 15 miles thick, and a very thin atmosphere, composed primarily of oxygen.
Scientists are almost certain that hidden beneath Europa’s icy surface is a saltwater ocean with about twice as much water as Earth’s global ocean.
The surface of the moon is constantly bombarded by radiation that breaks down the icy crust into oxygen and hydrogen gas.
Most of this gas is released from the surface, escapes into space, or remains behind to form Europa’s atmosphere.
However, it has been thought that these gases could also migrate into the interior of the ocean.
That means oxygen produced at the surface could potentially be drawn into the ocean, where it could support life forms.
These life forms could be tiny, like “extremophile” microbes that would be invisible to the human eye.
Hopes were raised further last year when a study revealed that Europa has CO2 on its surface, which on Earth is a byproduct of cellular function.
This look at the complex, ice-covered surface of Jupiter’s moon Europa came from NASA’s Juno mission during a close pass on September 29, 2022.
The surface of the moon is constantly bombarded by radiation that breaks down the icy crust into oxygen and hydrogen gas.
For the new study, Dr. Szalay and his colleagues analyzed data from a flyby of Europa by the Juno spacecraft on September 29, 2022, in which the spacecraft flew 220 miles above Europa’s surface.
They studied data from Juno’s Jovian Auroral Distribution Experiment (JADE) instrument, which detects and measures ions and electrons around the spacecraft.
From this data, they calculated that approximately 12 kilograms of oxygen are produced on the surface of Europa every second.
This is at the lower end of the expectations derived from previous models, which ranged between 5 and 1,100 kilograms per second.
“Europe’s atmospheric composition has never been directly sampled and model-derived oxygen production estimates ranged over several orders of magnitude,” the authors say.
What’s more, there still needs to be more evidence of how exactly oxygen from the surface can reach the underground ocean.
Previous studies have speculated that pools of salt water inside the shell could act as conduits to transport oxygen downward as a possible source of metabolic energy for life.
Juno, a solar-powered rotating spacecraft, arrived at Jupiter in 2016 after a five-year journey (depicted here in an artist’s impression)
The researchers studied data from Juno’s Jovian Auroral Distribution Experiment (JADE) instrument, which detects and measures ions and electrons around the spacecraft.
Ultimately, it could be up to future space missions to discover for sure whether Europa is suitable for extraterrestrial life forms.
In October this year, NASA will send its Europa Clipper spacecraft to investigate whether Europa has the capacity to support even the most basic organisms.
It is scheduled to enter the orbit of the Moon and begin its search in 2030, while Juno remains active and will continue operating until September 2025.
The new study has been published today in the journal. Nature Astronomy.