In the last two decades, we have established that this solar system is awash in water, albeit mostly dirty ice. That’s good news for our 98%-water species, at least in the very long term. Whatever else, we shouldn’t die out of thirst.
Even more interesting are the “ocean worlds“, icy moons of Neptune and Saturn (and, who knows, outer planets such as Pluto and Uranus), which probably have a liquid ocean underneath a thick crust of ice.
As I have noted earlier, ESA and NASA are gearing up to explore these worlds, because we just have to. A prime target is the large moon Europa, which has a fissured icy crust and, most likely, a watery ocean below.
This week Waite, J. Hunter and colleagues report on yet another moon, Enceladus, which also has an icy crust ovre a liquid ocean. Enceladus also has active volcanoes !spewing water vapor. Whoa!
Enceladus is also notable because the Cassini spacecraft actually visited and swooped through one of the volcanic plumes to take a sample.
As Waite et al report, this sample contains water with traces of several other species, including H2. (See  for the details of this non-trivial measurement, a billion KM from home.) The researchers are particularly interest in H2, because they theorize that it is generated by “ongoing hydrothermal reactions of rock containing reduced minerals and organic materials.” They also calculate that this indicates “thermodynamic disequilibrium that favors the formation of methane from CO2 in Enceladus’ ocean “ (p. 155)
The thermodynamics and Hydrogen are both highly favorable for microbes, so these findings suggest that the ocean is “habitable”. This makes Enceladus a tempting target for a landing mission.
““We’re pretty darn sure that the internal ocean of Enceladus is habitable and we need to go back and investigate it further,” said Cassini scientist Dr Hunter Waite from the Southwest Research Institute in San Antonio, Texas.” (quoted in )
So now we have at least two high priority “ocean worlds” that we
should must visit.
The good news is that the gear being developed will work for missions to either or both Enceladus or Europa.
It is difficult to be optimistic about the prospects for government funding for such missions (unless someone’s family can make a bundle off the “deal”).
But, why aren’t the Silicon Valley hobbyists all over this stuff? This is way more interesting than sending rich tourists into low Earth orbit, and probably cheaper, too.
So let’s all raise a glass to my new favorite, “Robots on Enceladus!”
Suck on that, Europa.
- Jonathan Amos, Saturn moon ‘able to support life’. BBC News – Science & Environment.April 13 2017, http://www.bbc.co.uk/news/science-environment-39592059
- J. Hunter, Waite, Christopher R. Glein, Rebecca S. Perryman, Ben D. Teolis, Brian A. Magee, Greg Miller, Jacob Grimes, Mark E. Perry, Kelly E. Miller, Alexis Bouquet, Jonathan I. Lunine, Tim Brockwell, and Scott J. Bolton, Cassini finds molecular hydrogen in the Enceladus plume: Evidence for hydrothermal processes. Science, 356 (6334):155-159, 2017. http://science.sciencemag.org/content/356/6334/155