Europa, one of Jupiter’s moons believed to be home to a warm ocean of salt water, has long been considered one of the best places in the solar system to search for extraterrestrial life. Now, the United States space agency, NASA , has confirmed the existence of geysers more than 100 kilometers high in Europe that could harbor some kind of life.
Thanks to data collected by NASA’s Galileo probe more than two decades ago , scientists confirm the presence of these giant water jets that are quite rare to find (they require a combination of water and heat and casual plumbing) but whose presence it has also been discovered on Enceladus or on Earth itself.
The study, published in the journal Nature Astronomy , adds to growing evidence that Europa is dumping its materials into space. If these plumes are confirmed and linked to Europa’s ocean, they could provide an incredibly straightforward way to scan the moon for signs of life – you wouldn’t have to land on the surface and drill into it, just fly to through the pen and analyze its content.
Scientists are already working to do just that. The launch of NASA’s Clipper and the European Space Agency’s Jupiter Icy Moons Explorer (JUICE) are scheduled for the early to mid-2020s, both equipped with high-resolution cameras and a host of other sensitive instruments.
“The idea that Europa could have feathers seems to be more and more real, and that is very good news for future exploration,” said Xianzhe Jia, a space physicist at the University of Michigan and lead author of the study.
The results of the Clipper and JUICE missions “could have enormous implications,” bringing us closer to understanding the question of whether we are alone in the universe, he clarifies.
Scientists have suspected since 2012 that Europa might harbor plumes , after the Hubble Space Telescope observed water vapor rising above the moon’s icy south pole.
No spacecraft has come close to Europa since Galileo, which crashed 400 km over the moon’s “hot spot” in December 1997.
That mission had a serious shortcoming: The spacecraft’s most powerful antenna could not be deployed after launch, limiting the amount of data the spacecraft could send to Earth. However, experts thought that if a plume existed, Galileo could have perceived its signatures with his magnetometer and plasma wave instruments.
Margaret Kivelson, a space physicist at the University of California, Los Angeles, confirmed his hunch.
Galileo discovered that Europa’s magnetic field intensified and changed orientation just as the spacecraft got closer to the moon . Then the data from the plasma wave instrument showed unusual emissions that could be associated with a high density of charged particles. The results didn’t make sense at the time, but they ‘re exactly what scientists would expect to find near a jet of speeding salt water.
They then ran the data through a sophisticated modeling program that compared the observations with what scientists might expect from a plume of the dimensions extracted by Hubble. The results confirmed what was expected.
Europe, the frozen moon
Europe is mainly made up of silicates. It has a crust of water ice and a probable nucleus of iron and nickel and also has a thin atmosphere composed of oxygen, among other gases.
According to experts, the source of the pen is not yet clear. The prevailing theory is that the water comes directly from the subsurface ocean of Europa and is being propelled upward by hydrothermal activity much like that which feeds geysers on Earth. But the water could originate elsewhere. Some have suggested that there may be a subsurface lake hidden between the thick ice sheets of Europa.
Considering that feather behavior is also unpredictable, the researchers hope this paper will inspire other scientists to keep looking at Europa’s feathers. Maybe someone else will find new clues by mining data from years ago.
Reference: Evidence of a plume on Europa from Galileo magnetic and plasma wave signatures, Nature Astronomy (2018). nature.com/articles/doi:10.1038/s41550-018-0450-z
Image credit: NASA / JPL-Caltech / DLR
