One of the prime locations to search for life beyond Earth in our solar system is Saturn’s moon Enceladus, which is thought to have an ocean of liquid water beneath its icy crust. Now, a new map of the moon made using both visible light and infrared shows where regions of geological activity have deposited fresh ice onto its surface.
As Enceladus is covered in ice, it is one of the most reflective bodies in our solar system and normally looks like a bright white snowball. So to understand more about this intriguing moon, NASA analyzed data from its Cassini mission to Saturn which ended in 2017.
Cassini had an instrument called the Visible and Infrared Mapping Spectrometer (VIMS) which recorded the way light bounced off Enceladus, separating the light into different wavelengths and allowing scientists to infer what materials make up the moon.
You can also view an interactive map of Enceladus which allows you to zoom around the moon.
The region shown in bright red is especially interesting, as it sits right on Enceladus’s south pole in a region with tectonic faults called the Tiger Stripes. The red color indicates that this region is spewing plumes of ice grains and vapor out onto the surface, correlated with this area of geological activity. That provides strong evidence that there is an ocean beneath the ice.
Importantly, the northern pole of the moon shows similar infrared features. This suggests similar geological activity has occurred at both poles, and that the northern pole was covered in fresh ice at some point in recent history. Both poles have been “resurfaced” by water coming up from the subsurface ocean, either as icy jets or as ice moving up through fractures in the crust.
“The infrared shows us that the surface of the south pole is young, which is not a surprise because we knew about the jets that blast icy material there,” Gabriel Tobie, VIMS scientist with the University of Nantes in France and co-author of the new paper, said in a statement. “Now, thanks to these infrared eyes, you can go back in time and say that one large region in the northern hemisphere appears also young and was probably active not that long ago, in geologic timelines.”
The next step is for scientists to see if this technique could reveal information about other icy moons, to compare them with Enceladus.
The research is published in the journal Icarus.