Enceladus is Saturn’s sixth largest moon, being a small frozen ball about 500 km in diameter. Despite this, the small moon came to attention when the Cassini spacecraft discovered evidence of a large ocean beneath the ice sheet that envelops the entire world.
The ocean there is very different from what we know here on Earth – here it is very shallow (average depth of 3.6 km) compared to the estimated depth of the ocean of Enceladus, about 30 km deep. The terrestrial ocean is hotter on the surface, as it is heated by the sun’s rays, while the Saturn satellite is cooler at its top and heated in its depths by its hot core.
Another point in common with the Earth is that the ocean in Enceladus is also salty. The new study suggests that salt levels may vary by region – which can directly contribute to water circulation patterns. If confirmed, this behavior would be similar to the waters around Antarctica. In gravitational measurements obtained by Cassini, it is observed that the ice layer tends to be thinner at the poles, which may indicate the melting of the ice in that region. Co-author of the article, Andrew Thompson, professor of Environmental Science and Engineering at the California Institute of Technology (Caltech), says: “understanding which regions of the subsurface ocean may be the most hospitable for life, as we know it, can one day inform efforts to search for signs of life “.
The defrost and freeze dynamics in the regions of the Enceladus poles would directly affect the dynamics of ocean currents. As the salt water freezes, the salt “leftovers”, which in turn makes the surrounding water heavier – which sinks. Meanwhile, the melting of the ice provides an opposite dynamic: diluting the salt and decreasing the density of the water. Thompson and Ana Lobo, a geophysics student at Caltech, found that, based on what we understand from the Antarctic oceans, the Enceladus freeze and thaw regions would be connected by ocean currents that would form a current pattern from the poles to the equator – which it could carry heat and nutrients across the moon.
Confirming these possible characteristics in Enceladus is also important for future missions in the small frozen world. While waiting for new probes to be sent to Encélado, the researchers follow their studies with data already collected by the Cassini spacecraft – with its mission ended in 2017 – and telescopic observations of the small moon. The full article can be accessed at Nature Geoscience.
Did you like this article?
Subscribe your email to Canaltech to receive daily updates with the latest news from the world of technology.
Get the latest news delivered to your inbox
Follow us on social media networks