Water plumes over Europa Options

[Paolo]

Has a area on europa been narrowed down to the possible activity?

the paper I linked above has tentative identifications of the areas of possible activity

[antipode]

On the arxiv:

Probing for Evidence of Plumes on Europa with HST/STIS
W. B. Sparks, K. P. Hand, M. A. McGrath, E. Bergeron, M. Cracraft, S. E. Deustua

http://arxiv.org/pdf/1609.08215

P

[briv1016]

Is there any chance of further study with JunoCam? How does JunoCam's untargeted flyby resolution compare with Hubble?

[ChrisC]

This NASA press conference was done as a telecon, with reporters calling in and looking at graphics online, and NASA does not archive those telecons. Sometimes they briefly mention a phone number at the end (not the same number ...) you can call to hear a replay of the telecon, but you have to ... listen to the telecon to hear that number! So infuriating.

However, in recent years I've found that SOMEONE will inevitably record the call and then put it online. I just have to keep searching for it, or monitoring the threads here at UMSF and at NSF and see if someone posts it. Lo and behold, yesterday I came across this upload. The guy has taken the audio and synced it to the graphics, so in one video you have everything you need to enjoy a full hour discussion. FAR more information than is covered in the print press releases, or any news story you'll find.

As public thanks to the guy who did this, I'll mention him here:
Matthew Travis / Zero-G News / http://www.zerognews.com / https://www.facebook.com/ZeroGnews

Thank you dude! Click below for the full press conference.

https://www.youtube.com/watch?v=DoUDxseG8xw

[Phil Stooke]

briv1016:

"How does JunoCam's untargeted flyby resolution compare with Hubble?" (for Europa)

This helps to answer your question:

http://www.planetary.org/blogs/guest-blogs...ters-moons.html


Phil

[JRehling]

This eluded me till now, but an interesting consequence of the methodology is that it's blind to plumes that might erupt near the sub-jovian or anti-jovian point – perhaps to far over half of the surface of Europa. So, if the distribution of plume sources is random, detection of plumes on three of ten observations may imply that the number of plumes active at any given instant is far in excess of unity. On the other hand, the distribution of plumes is, of course, unknown, so the number of active plumes may average closer to 30%. If plumes occurred only near the poles, then the lower number would be more accurate, but the observation of one non-polar plume dispels that restriction.

That is, overall, the best news out of all of this. It seems like a multiple mission can expect probably to have a chance to observe sample plumes during its operations, although we're still beholden to unknown variability on longer timescales. But I think we're getting closer to being able to gamble on a mission architecture that is counting on plumes to occur during its operations. The downside is, we don't know where the active plumes will be, so any such mission would need to have a flexible timeline.

[MarcF]

Some strong new evidences for water plumes on Europa:
http://iopscience.iop.org/article/10.3847/2041-8213/aa67f8


links to pictures;

Hubble Sees Recurring Plume Erupting From Europa:
https://photojournal.jpl.nasa.gov/catalog/PIA21443

Europa's Plumes Located near 'Warm Spot' on Europa:
https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA21444

[stevesliva]

Mike Brown with some words on searching for hot spots with terrestrial telescopes:
http://www.mikebrownsplanets.com/2017/04/europa-is-hot.html

[Julius]

Plume activity on Europa would indicate a link between an underlying ocean and the surface. That would perhaps favour the thin ice model versus the thick ice model for Europa which I believe has been an ongoing controversy in Europa science for the past 30 years or so.

[MarcF]

Could we imagin a relationship between this unusual warm region (and its potential plume activity) and the very close Pwyll crater (cracks or very thin ice due to the recent impact that formed Pwyll) ?

[JRehling]

Plume activity on Europa would indicate a link between an underlying ocean and the surface. That would perhaps favour the thin ice model versus the thick ice model for Europa which I believe has been an ongoing controversy in Europa science for the past 30 years or so.

Some more recent research suggests that neither thin-nor-thick models can explain what we've seen, and that the resolution may be lens-shaped lakes of liquid water that are, typically, surrounded by ice on all sides and are ~half-way down, in contact with neither the surface nor the underlying ocean.

http://adsabs.harvard.edu/abs/2014AGUFM.P53B4008J

So, plumes may indicate that a lens-melt lake is currently venting into space, and are agnostic as to whether or not such water is currently (or recently, or even ever) in contact with the ocean.

However, the dark staining of ice where melt-through / venting seem to have occurred provide evidence that whatever water does vent upwards contains a significant non-water component, which might mean that the lakes and ocean exchange water on some basis.

The lens-melt lake hypothesis as a bridge between the thin-thick Europa debate reminds me of the arguments over the nature of light, with it turning out, eventually, that proponents of the wave explanation and the corpuscle explanation were both somewhat right and somewhat wrong. With Europa, we need confirmatory evidence that Europa Clipper should provide.

[hendric]

I hope someone requested new auroral time-lapse images for Jupiter as well. Be interesting to see how quickly the Europa hot spot in the aurora varies vs potential plume activity.

https://www.newscientist.com/article/dn8994...as-light-touch/

[stevesliva]

The hot spot's *not* hot.
http://www.mikebrownsplanets.com/2017/08/europa-is-hot.html

It has higher thermal inertia.

[MarcF]

New thermal map of the surface of Jupiter's ocean moon Europa by ALMA highlights one spot on the moon that is inexplicably cold. The spot is localized at 90°W and 23°N, in the northern part of Europa’s leading hemisphere. These coordinates are close the Murias Chaos, the Mitten !

“We don’t yet have a good explanation of what the cold spot means,” Trumbo said. “But, since we see the same anomaly twice, at two different times of the Europa day, we think it must be a region that is distinct in its thermal properties, and that could be interesting.”
The team noted that the location does have Europa’s highest water ice concentration and is also almost directly opposite Pwyll. However, neither of those facts can explain that spot’s strange thermal properties, they say.
“We should be able to learn more about this spot with more ALMA [data] and perhaps spectroscopic observations,” Trumbo said, “but we will probably not know if it correlates with unique geology until the Europa Clipper mission.”

A second thermal anomaly seems to correspond to the warm spot localized at the Pwyll crater previously detected and discussed in this topic.

Regards
Marc.

[HSchirmer]

The team noted that the location does have Europa’s highest water ice concentration and is also almost directly opposite Pwyll. However, neither of those facts can explain that spot’s strange thermal properties, they say.

Hmm, IIRC, UC Boulder had a few papers on how depressions in melting snowpacks would develop vertical ice-pipes that resisted melting,
because counter intuitively, the melt water freezes solid and is BETTER at conducting away heat than the snow is.

I wonder if this might be a similar "lack of surface snow" sort of conduction effect.