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What will Juice tell us about Europa?

  1. Apr 19, 2012 #1
    Now that ESa have selected Juice as its next main mission it seems dissapointing that the main target is Ganymede rather than Europa.
    I guess this is due to the extra cost of extra radiation shielding for Europa and due to the fact that NASa were supposed to do Europa as part of the original Laplace mission.

    So given Juice plans only 2 fly bys of Europa what will we really learn?
    Will it definitley answer the ocean hypothesis and measure the depth fo the ice sheet?
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  3. Apr 19, 2012 #2


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    All in all, I've always considered Ganymede a lot more interesting moon to explore than Europa. So I hope the JUICE mission stays funded and goes ahead and stays focused on Ganymede. From what I can see they plan for the craft to ORBIT Ganymede for several months.

    I don't think Europa is likely to be unique in having a subsurface saltwater ocean. Do you think there is something special about Europa that makes it extra interesting?

    Details about Ganymede:

    Largest moon in solar system (bigger than the planet Mercury)
    surface gravity about 1/7 of Earth's
    has its own internal geomagnetic field
    density about twice that of water ( about 2 g/cc)
    assumed makeup about half water-ice and half rocky material etc.
    likely subsurface saltwater ocean.

    Not bathed in deadly radiation, at least not to the extent that Europa is.
    Correct me if you think I'm wrong, but it seems obvious that Ganymede is the J-moon best suited for colonization by Earth life.

    By comparison, Europa is small and bathed in radiation. Is there some reason to bother with it?
    http://en.wikipedia.org/wiki/Ganymede_(moon [Broken])
    Last edited by a moderator: May 5, 2017
  4. Apr 19, 2012 #3
    I think the reason why Europa tickles the fancy of many a person interested in space is because of Mr. Clarke's excellent novels and their depictions of life on that particular moon. As I am no exobiologist, I do not know how realistic his ideas were, and I also have never seen (nor gone looking to find) a person say exactly why it would be unlikely for those creatures to be possible.

    But of course you raise good points for why Ganymede would be a possible place to put people in the future.
  5. Apr 19, 2012 #4
    I think finding signs of life is the key issue rather than colonisation. As I understand it Europa gets more press due to the higher probability of interaction between the surface and the ocean this increases the odds for life and for us to find signs of that life. Also there's more energy available for life at Europa than Ganymede. Life should be protected from the radiation by the ice sheet. If we are every going to drill to the ocean , it's going to be easier at Europa as it's believed to be closer than Ganymede.
    Am I wrong?
  6. Apr 20, 2012 #5
    I am very interested in the Juice missions and I sincerely hope it goes ahead as planned and within budget.

    If we are ever going to find any non terrestrial life then I think the Jovian moons are the place to start - who knows: it may be that beneath the ice sheets of the J-moons are complex ecosystems. Assuming all the requirements for life!

    I am in no way talking about little green men but we shall see - there have been detections of organic compounds by Cassini so the possibilty is there!
  7. Apr 20, 2012 #6
    If I had to choose, I'd choose Europa. That's because Europa has gotten resurfaced much more recently than either Ganymede or Callisto. That's from counting craters. Hardly any on Europa, but lots of them on Ganymede and Callisto.
  8. Apr 28, 2012 #7
    Interesting comment. On what basis should we suspect that the temperature might be warm enough to melt ice? Is the orbit eccentric enough to develop a sub-surface tidal warming along the lines of Io?

    An alternate perspective in support of investigating Europa is that a life form that is not sensitive to the frigid temperatures likely to be prevalent on Europa may neither be sensitive to radiation.
  9. Apr 28, 2012 #8
    I'm with you there buddy! I recently discovered the Cassini-Huygens website. The photographs and descent animations for Titan are just spectacular! Way underbilled. The general public should experience them as they really are a dream to either a science or science fiction fan. It's almost like waking up on a planet not so very far away that is close enough to our own to start feeling at home in a strange way.
  10. Apr 29, 2012 #9
    High Tide on Europa - Astrobiology Magazine
    So from some of the modeling, Europa seems to have enough tidal heating to keep its interior ocean liquid.

    Surf's Up on Europa? - NASA Science
    It's unlikely to have any other kind, like a liquid-iron core. That's what the Earth has.

    But how thick is the surface ice?
    The great thickness debate: Ice shell thickness models for Europa and comparisons with estimates based on flexure at ridges
    The authors note that their colleagues had found a lot of different numbers for the ice-shell thickness, and they themselves think that it can be different at different places on Europa.
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