Saturn's moon Titan may have ocean as salty as the Dead Sea
Sen—The Cassini spaceprobe’s repeated flybys of Saturn's largest moon, Titan, have revealed that the smoggy world may have an interior ocean that is as salty as the Dead Sea on Earth.
The NASA/ESA mission made regular measurements of the moon's gravity and terrain during those close encounters. (It finished its 100th flyby in May, and just completed another flyby a few days ago.)
Scientists tested what substances might give the results they were observing. The gravity measurements best made sense when researchers modelled a very salty combination of water replete with substances including potassium, sodium and sulphur.
"This is an extremely salty ocean by Earth standards," said research lead Giuseppe Mitri of the University of Nantes in France.
Artist's conception of the Cassini spacecraft. Image credit: NASA/JPL-Caltech
"Knowing this may change the way we view this ocean as a possible abode for present-day life, but conditions might have been very different there in the past."
Titan's dense mix of hydrocarbons display what some scientists say is similar to "prebiotic" chemistry on Earth, meaning what was around our planet before life arose. Titan is believed to be a swampy planet that has a hydrological (liquid) cycle that is also similar to our planet. While our planet is warmed by the sun, Titan receives its energy from repeated interactions with its massive gas giant planet.
The researchers additionally found information about the ice shell surrounding Titan's interior. Cassini discovered that its thickness is not consistent, which could be the case if the shell is freezing and crystallizing. NASA stated that the freezing could have "important implications" for any life present in the ocean, because the ice would serve as a barrier between the ocean and the surface.
Titan's atmosphere makes Saturn's largest moon look like a fuzzy orange ball in this natural-color view from the Cassini spacecraft. Image credit: NASA/JPL-Caltech/Space Science Institute
With that being the case, scientists are interested in how methane was detected in the moon's atmosphere. They believe that there must be "hot spots" that allow the methane to bleed through to the atmosphere, since there doesn't appear to be enough to be there through plate tectonics or convection (fluid movements) changing the ice. Methane is a short-lived element in the atmosphere, yet Titan is known to have at least five per cent methane.
"Our work suggests looking for signs of methane outgassing will be difficult with Cassini, and may require a future mission that can find localized methane sources," said co-author Jonathan Lunine, a scientist on the Cassini mission at Cornell University in New York. "As on Mars, this is a challenging task."
The research was published in the journal Icarus.