Water plumes over Europa |
Water plumes over Europa |
Sep 7 2018, 12:44 PM
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#121
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Senior Member Group: Members Posts: 1591 Joined: 14-October 05 From: Vermont Member No.: 530 |
vertical ice-pipes You mean like penitentes? Wikipedia calls them "almost a black body" https://en.wikipedia.org/wiki/Penitente_(snow_formation) |
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Sep 7 2018, 06:08 PM
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#122
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Member Group: Members Posts: 684 Joined: 24-July 15 Member No.: 7619 |
You mean like penitentes? Wikipedia calls them "almost a black body" Well, conceptually similar - ice structures grow due to "phase change" as water forms ice and accumulates in areas with higher heat loss. But penitenties are sublimation and radiative heat loss to the sky, while ice pipes are snowpack melting and conductive heat loss to the ground. So, practically, think "upside down penitentes". Found it- red aeolian dust changes how snowpacks melt- the variation in ice column morphology between red and clean snow gives insight into how dust deposition events may affect the energy balance, subsequent melt, and meltwater flowpaths in snow covered areas The movement of liquid water through the snowpack in “red” snow thus appears to be more uniform, decreasing the size of preferential flowpaths that give rise to ice columns. |
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Oct 9 2018, 12:41 PM
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#123
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Junior Member Group: Members Posts: 59 Joined: 25-December 05 From: Stevens Point, Wisconsin, USA Member No.: 619 |
Well, conceptually similar - ice structures grow due to "phase change" as water forms ice and accumulates in areas with higher heat loss. But penitenties are sublimation and radiative heat loss to the sky, while ice pipes are snowpack melting and conductive heat loss to the ground. So, practically, think "upside down penitentes". Found it- red aeolian dust changes how snowpacks melt- the variation in ice column morphology between red and clean snow gives insight into how dust deposition events may affect the energy balance, subsequent melt, and meltwater flowpaths in snow covered areas The movement of liquid water through the snowpack in “red” snow thus appears to be more uniform, decreasing the size of preferential flowpaths that give rise to ice columns. Penitentes up to 15 m high, spaced 7.5 m apart at the equator? Challenging for a lander... https://www.nature.com/articles/s41561-018-0235-0 |
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Jul 25 2019, 02:22 PM
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#124
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Senior Member Group: Members Posts: 1591 Joined: 14-October 05 From: Vermont Member No.: 530 |
First bright stellar occultation for Europa:
http://sci.esa.int/gaia/61491-astronomers-...thanks-to-gaia/ Relevant to this thread because the Hubble data was, I think, derived from Europa occulting Jupiter. Surprised it's the first! |
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Nov 18 2019, 07:31 PM
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#125
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Junior Member Group: Members Posts: 66 Joined: 3-August 12 Member No.: 6454 |
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Nov 19 2019, 05:45 AM
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#126
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
This is an exciting result. The intermittent nature of the plumes may create a challenge for Europa Clipper to sample them without some flexibility to alter the mission in response to unpredictable events.
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Jun 25 2020, 10:42 AM
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#127
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Member Group: Members Posts: 362 Joined: 13-April 06 From: Malta Member No.: 741 |
I still cannot come to terms with the idea that Europa has moved from tectonics (ridge formation) onto chaos as the ice crust has thickened over its 4 billion year history. I guess radar should tell us a lot about what is actually happening.
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Jun 27 2020, 05:27 AM
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#128
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
From Nimmo and Manga (2009):
"The manner in which Europa’s shell and interior evolved to their present-day states represents a major unsolved problem for at least three reasons. First, the present-day state, especially of the silicate interior, is poorly known. Second, Europa’s surface may only record the last 1% of its existence, so there are few constraints on its earlier history. Third, the thermal and orbital evolution of Europa are intimately coupled in a manner that is nontrivial to model." https://websites.pmc.ucsc.edu/~fnimmo/website/draft5.pdf One significant work since then was the melt-lens model of Schmidt, et al (2011): https://www.nature.com/articles/nature10608?proof=trueNov In a nut [ice] shell, the internal dynamics and certainly the history of Europa's ice shell are far from determined, although the tidal forces that create the most visible linea have probably been modeled well. Even after one or several more missions, I doubt if we will have good information about the history of Europa's ice shell pre-dating that "last 1%" but finding out what's going on there now is something I'm very much looking forward to. |
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Jul 12 2022, 05:58 PM
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#129
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Member Group: Members Posts: 251 Joined: 14-January 22 Member No.: 9140 |
This is just a teaser for now, but JWST will attempt to detect and characterize any Europa plumes, which were detected, but at low signal, by HST, and were detectible only sometimes. JWST has the capability to detect spectral features that HST is simply not capable of, those above 2.5 microns. That corresponds to CO2, among other possible components. Of course, what it actually detects will depend on what, if anything, is actually there when it observes.
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Oct 6 2022, 03:01 AM
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#130
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Senior Member Group: Members Posts: 1276 Joined: 25-November 04 Member No.: 114 |
^ I was unable to find observation dates on this.
Has this already occurred? |
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Oct 6 2022, 04:16 AM
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#131
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Member Group: Members Posts: 251 Joined: 14-January 22 Member No.: 9140 |
This indicates that the first observations are planned for November and December, 2022.
https://www.stsci.edu/jwst/science-executio...on.html?id=1250 Jupiter is just past opposition now, so it will be a bit farther than is optimal when the observations are made; I guess the competition for observing time led to the later dates. Also, there are constraints on the observations as they will want Europa to appear far from Jupiter's disk. Also note that this same observation program, 1250, includes observations of Enceladus. |
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Oct 6 2022, 06:58 PM
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#132
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Senior Member Group: Members Posts: 2106 Joined: 13-February 10 From: Ontario Member No.: 5221 |
I recall that JWST cannot be pointed directly away from the Sun, so it cannot never take opposition period images of any outer planet (though at such distances its not a major issue, I think).
See here: https://jwst-docs.stsci.edu/jwst-observator...ing-constraints |
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