Preventing the Forward Contamination of Europa (2000) / Chapter Skim
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2 Europa
2 Europa
Pages 7-12
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High-resolution images of the surface show features that are best or most easily explained as resulting from the presence of at least partially melted material at shallow depths.2 These features include plates of ice that appear to have rafted to new locations and then frozen in place (Figure 2. 1~3 4 and cycloidal cracks that can be interpreted as being due to the effects of diurnal tidal stresses on a surface ice shell decoupled from Europa's interior (Figure 2.2~.5 FIGURE 2.1 This view of the Conamara Chaos region of Europa shows an area where the icy surface has been broken into many separate plates that have moved laterally and rotated with respect to each other.
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From page 8... ...
This contrary view has, however, been challenged on the grounds that even if the ocean is reducing, abundant redox chemistry could still take place, providing an energy source for metabolism.8 Another possibility is that life exists not in the deep oceanic interior of Europa but near the surface. If this is the case, then the ultimate power source for a europan biosphere may be chemical species created by interactions between the surface ice and energetic particles in the Jovian radiation environment.9 While no evidence for life exists, it is the potential for life that makes Europa an exciting target for further exploration.
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From page 9... ...
The particular scientific goals of the first mission are expected to be determination of whether a global ocean of liquid water exists beneath the icy surface, determining, if possible, the spatial and geographical extent of liquid water, determining the bulk composition of the surface material, and characterizing the global geologic history and the nature of any ongoing surface and atmospheric processes. These science objectives can best be met by one or more near-polar-orbiting spacecraft.
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From page 10... ...
Galileo magnetic field and charged-particle data also imply that the radiation environment varies across the surface of Europa, being only one-fifth as high over the leading hemisphere as over the trailing hemisphere. This happens because the ice surface of Europa absorbs trapped particles as magnetic flux tubes drift across the moon from trailing side to leading side (owing to magnetospheric rotation)
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From page 11... ...
Paranicas of the Applied Physics Laboratory, Johns Hopkins University. REFERENCES ' Space Studies Board, National Research Council, A Science Strategyfor the Exploration of Europa, National Academy Press, Washington, D.C., 1999.
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From page 12... ...
'I Space Studies Board, National Research Council, A Science Strategy for the Exploration of Europa, National Academy Press, Washington, D.C., 1999.
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