Other
Scientific paper
Jun 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008phdt........25c&link_type=abstract
Proquest Dissertations And Theses 2008. Section 0246, Part 0606 119 pages; [Ph.D. dissertation].United States -- Virginia: Univ
Other
Europa, Auroral Emissions, Planetary Atmospheres, Space Weathering
Scientific paper
Jupiter's icy moon Europa is bombarded by radiation that erodes the surface, launching molecules into a very thin "atmosphere." The atmosphere is dominated by atoms and molecules, such as H 2 O, O 2 and H 2 , produced from the mostly water ice surface. However, this atmosphere is also known to have species representative of interesting trace materials in its icy surface.
Previous observations of Europa found non-uniform auroral emissions from its atmosphere. UV emissions from O 2 were brightest above bright terrain, which consists of relatively pure water ice, while visible-light emissions seen in eclipse were brightest above relatively dark terrain. I attempted to explain these emissions using the assumption that the non-uniform brightnesses are due primarily to non-uniform atmospheric densities. That the O 2 atmosphere would
be spatially non-uniform was surprising because its long lifetime and volatility should result in its redistribution around the globe. I was able to create a non-uniform atmosphere by stipulating that the dark terrain is an O2 sink. I discuss reasons that such a sink might exist and conclude that the porous nature of Europa's regolith is critical to any loss process. Reproducing the Na observation required that the Na is concentrated in Europa's dark terrain and is sputtered (ejected) along with the H 2 O, a scenario consistent with the tentative identification of Na 2 SO 4 and other salts in dark terrain spectra. A molecular dynamics simulation of sputtering showed that trace species present in the surface, such as Na, would be carried off with the 10 to 10 4 H 2 O molecules ejected by each incident ion. These results have implications for future spacecraft exploration of Europa. The modeling of Europa's atmosphere depended on my earlier simulations of the effect on surface porosity on the lunar atmosphere. I also modeled, in detail, the atmospheres of two species that have been detected in Europa's icy surface: CO 2 and SO 2 . These molecules provide an interesting contrast in spatial distribution and volatility. Detecting such trace species with moderate time and space resolution would allow us to constrain important aspects of surface composition, chemistry and to study space weathering processes.
No associations
LandOfFree
Europa's tenuous atmosphere does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Europa's tenuous atmosphere, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Europa's tenuous atmosphere will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1250069