> This remarkable transformation in our understanding is the result of just three missions: Voyager, Galileo, and Cassini—along with some computer modeling and hard staring by the Hubble and Webb space telescopes.
Seems odd to neglect to mention New Horizons immediately after mentioning the probable existence of liquid oceans under Pluto's surface, a finding made possible thanks primarily to New Horizons.
idlewords 6 hours ago [-]
No shade on New Horizons intended, but I was talking about the early 2000's revolution in understanding of ice moons/ocean worlds, and that preceded the Pluto flyby by a lot.
It was a valuable piece of corroborating evidence, but not shocking and unexpected in the way results from those three missions were. We had good reason to believe Pluto would look a lot like Triton, and it does.
yellowapple 5 hours ago [-]
Fair enough, though how common was that belief that Pluto would look like Triton? Before the first photos from New Horizons pretty much every artistic rendition of Pluto I'd seen was a solid ball of rock and/or ice, more like Ceres than Triton.
idlewords 4 hours ago [-]
Both were known to be Kuiper Belt objects, so it was expected there would at least be a family resemblance. I don't think anyone expected Pluto to be more active than Triton; that was certainly a surprise.
If there are planetologists reading the thread, I'd love to hear a more authorative perspective than mine!
3eb7988a1663 3 hours ago [-]
I was born in a water moon.
exhilaration 1 days ago [-]
Great read, other than Europa I wasn't aware of these other candidate ocean moons.
miohtama 1 days ago [-]
TIL
> The radiation environment around Europa is punishing; an astronaut standing on the surface would get a fatal dose in about a day
kaseijin 1 days ago [-]
True for all the Galilean Moons more or less. Their orbits all lie within the Jovian equivalent of the Van Allen belts. And Jupiter's magnetic field is much stronger than earth's.
sennalen 1 days ago [-]
Not Callisto. Being within Jupiter's magnetosphere but out of reach of Io's shenanigans makes it one of the mildest radiation environments in the solar system.
stackghost 2 hours ago [-]
I'm interested in learning more about "Io's shenanigans". What are you referring to?
idlewords 1 days ago [-]
Not true at all, the daily dose on Ganymede (which has a magnetic field of its own) is ~70 mSv/day, and Callisto is 0.1 mSv/day.
Io, meanwhile, is 35 Sv/day. Location really matters among the four Galilean moons.
pvaldes 1 days ago [-]
Beautifully designed article. Very cool images and diagrams.
> We want rocks in contact with water,
But there is ice compressed between the water column and the xenoceanic bottom, ok. I see the problem.
What about rocks in the surface of the water?. Some volcanic rocks can float.
andrewflnr 10 hours ago [-]
> What about rocks in the surface of the water?. Some volcanic rocks can float.
This is... not something you lay plans on. Even on Earth, these rocks are formed at surface pressure, just barely float, and don't float for long (I've tried). If they form in the deep ocean, I'm guessing the pressure isn't going to let the bubbles be big enough to create bouyancy at all. Either way they would be super rare.
Gravityloss 11 hours ago [-]
I guess I'm now officially old and cranky, as planetoids receiving glow-ups was just a bit much as a term.
Europa Clipper, launched 2024, starts Europa flybys on March 2031
Dragonfly, hopefully launching July 2028, arriving on Titan 2034
https://en.wikipedia.org/wiki/Europa_Clipper
https://en.wikipedia.org/wiki/Dragonfly_(Titan_space_probe)
Seems odd to neglect to mention New Horizons immediately after mentioning the probable existence of liquid oceans under Pluto's surface, a finding made possible thanks primarily to New Horizons.
It was a valuable piece of corroborating evidence, but not shocking and unexpected in the way results from those three missions were. We had good reason to believe Pluto would look a lot like Triton, and it does.
If there are planetologists reading the thread, I'd love to hear a more authorative perspective than mine!
> The radiation environment around Europa is punishing; an astronaut standing on the surface would get a fatal dose in about a day
Io, meanwhile, is 35 Sv/day. Location really matters among the four Galilean moons.
> We want rocks in contact with water,
But there is ice compressed between the water column and the xenoceanic bottom, ok. I see the problem.
What about rocks in the surface of the water?. Some volcanic rocks can float.
This is... not something you lay plans on. Even on Earth, these rocks are formed at surface pressure, just barely float, and don't float for long (I've tried). If they form in the deep ocean, I'm guessing the pressure isn't going to let the bubbles be big enough to create bouyancy at all. Either way they would be super rare.