You could - $$$$$.IIRC, the major problem w/Europa is that it is so deep in Jupiters' trapped radiation belts that you basically have around 30 days (+/- YMMV) from the time you enter orbit until your electronics are fried.Enter orbit, do a survey, pick a landing spot, de-orbit/land, surface ops - all in 30 days or less. Sounds just a bit dicey to me.Again IIRC, the cost of the rad-hardened electronics and radiation vault was killing JEO. Jupiter is a tough place.(Blackstar, pls feel free to correct me/kick me in the head if I'm wrong anywhere in there).
Just out of curiosity how does the vintage vacuum tube electronics fare in the radiation environment around Jupiter in comparison to modern IC electronics?
Well, yes, other than the fact Callisto's ice shell is modeled to be roughly an order of magnitude thicker and the existence of geothermal energy sources at the rock/liquid interface is questionable. People want to land on Europa not because it's super hard, but because of its astrobiological potential. In that light your suggestion reminds me of looking for your car keys where the light is good, not where you dropped them.
There are places on Callisto where eruptions/geysers/fumaroles take place.
A 375 km x 225 km region at 1°S, 6°W (Figure 17.18)shows a landscape with numerous pits, which often occurin clusters (Moore et al. 1999). They are sharply outlined,closed depressions with steep walls but no raised rims.
Callisto’s pits may have formed from initially unremarkable local depressions by differential sublimation of a volumetrically substantial volatile.
Along with the discovery of Callisto’s conducting layer, major Galileo discoveries about Callisto include the complete absence of cryovolcanic resurfacing, the relatively undifferentiated interior, and the presence of massive landform erosion likely from sublimation processes.
Callisto, once unknown and then disregardedafter Voyager, has emerged in the post-Galileo era worthyof the same intense scientific scrutiny that is lavished uponher siblings
I didn't say there was major cryovolcanic activity on Callisto.
I was thinking of the apparent morphological similarity between the pits described by Moore et al. and the pits in the Spudis article.
Sure, these hypotheses are not what Moore et al. invoke to explain the pits, but so what? They're as good an explanation as what Moore et al. offered, which was written a few years before the Mercury results came out.
We simply do not know enough about Callisto to infer that there is absolutely no communication between the salty see that underlies the icy crust and surface itself.
Since you skimmed the book chapter from the most important book on Jupiter, you may have missed the conclusion:
I agree that Callisto is treated a little like the ugly sister, unfairly to a certain extent.
It's easy to get a single concept, like "lots of radiation, impossible to do more than 30 days" and then stop thinking about it because the trade is too complex.
Not an exact substitute (nothing ever is), but we've never landed on any icy moons at all (unless you count Titan, but that seems like a stretch).
Quote from: Robotbeat on 01/10/2012 05:52 pmNot an exact substitute (nothing ever is), but we've never landed on any icy moons at all (unless you count Titan, but that seems like a stretch).Why is Titan a stretch?Yes, we've never landed on anything else in the outer solar system and the present and likely future funding constraints ensure we will land on very few additional places. Thus we can't really afford to visit the "less interesting" places, but need to prioritize. You can't just build a Discovery class mission and try it out on Callisto. It would be nice if you could.I'm all for landing on every single rock out there. If you look close enough each is unique and interesting in some way, but dreaming is one thing. Being realistic and practical is another.
Quote from: Warren Platts on 01/10/2012 05:28 pmI didn't say there was major cryovolcanic activity on Callisto.I never said you claimed major activity. You obviously did claim activity, for which there simply is no evidence.
QuoteI was thinking of the apparent morphological similarity between the pits described by Moore et al. and the pits in the Spudis article.Morphological similarity is not a very convincing argument, especially when observations from rocky bodies are applied to mostly icy bodies.
QuoteSure, these hypotheses are not what Moore et al. invoke to explain the pits, but so what? They're as good an explanation as what Moore et al. offered, which was written a few years before the Mercury results came out.Not every explanation is as good as any other. There are those which are better supported by evidence and those which aren't.
QuoteWe simply do not know enough about Callisto to infer that there is absolutely no communication between the salty see that underlies the icy crust and surface itself.We don't. Since everyone seems to agree that in terms of astrobiological potential Europa rates significantly higher than Callisto, what do you hope to figure out about Europa by exploring Callisto? Their composition and evolution histories are significantly different. At the end of the day you will have learned about Callisto, not Europa.
QuoteSince you skimmed the book chapter from the most important book on Jupiter, you may have missed the conclusion:I haven't missed that. I never said Callisto isn't worth exploring. I'm saying it's not a substitute for Europa. It's certainly off topic for this particular thread.
Of thetwo icy Galilean satellites, it would be more plausible for Ganymede to have a subsurfaceliquid water ocean. Ganymede is completely differentiated and extensive endogenicmodification of its surface and the existence of an intrinsic magnetic field’ imply adynamic interior in the past and even to the present28, Perhaps Ganymede also has aninternal liquid water ocean if Callisto has one, but Ganymede’s intrinsic magnetic fieldobscures any induction signal.
Quote from: Robotbeat on 01/10/2012 05:52 pmNot an exact substitute (nothing ever is), but we've never landed on any icy moons at all (unless you count Titan, but that seems like a stretch).Why is Titan a stretch?