Water plumes over Europa Options

[vjkane]

Just to enlarge on this, the Cassini Phase A report in 1988 clearly shows the degree of interest, declaring Iapetus and Enceladus the two icy satellites of particular interest, noting (section 3.4.2)
'The strange appearance of Enceladus surface and the location of the ephemeral E-ring may be a coincidence, but there is a strong probability that they are connected in some manner, possibly through current eruptive activity on Enceladus'

Yeah, I blew it on this one. I was focused on the contrast in level of activity of Enceladus (which I think (corrections welcome!) was not expected) with the possible level at Europa. I remember being at JPL for one of the Voyager flybys when I believe I first heard the idea that Enceladus might have some volcanic idea was discussed.

[nprev]

Nobody's keeping score, man.

If I could pick one theme for exploration of the Solar System to date it would be "expect the unexpected".

[TheAnt]

Not plumes, but another matter about Europa, signs of plate tectonics though the word that comes to my mind is ice shear. Regardless of what term to use, this explains surface features of Europa.

[Fran Ontanaya]

No confirmation for plumes yet:

http://www.scientificamerican.com/article/...rs-are-missing/

[Hungry4info]

NASA to Hold Media Call on Evidence of Surprising Activity on Europa
http://www.nasa.gov/press-release/nasa-to-...vity-on-europa/

NASA will host a teleconference at 2 p.m. EDT Monday, Sept. 26, to present new findings from images captured by the agency’s Hubble Space Telescope of Jupiter’s icy moon, Europa.

Astronomers will present results from a unique Europa observing campaign that resulted in surprising evidence of activity that may be related to the presence of a subsurface ocean on Europa.

[JRehling]

NASA to Hold Media Call on Evidence of Surprising Activity on Europa

The headline has intriguing hints. Watery plumes were seen in the past, but appeared to be intermittent. If they had another burst of activity comparable to those seen in the past, it would not be "surprising." So what is up?

It is also hinted that the observations were made during a unique observational opportunity. Europa doesn't have seasons, so the only kinds of unique opportunities that I can think of would be eclipses and transits (not that unusual) and stellar occultations (unusual). The latter would allow, probably, better observations of composition than could be made from reflected sunlight.

Jupiter and Ganymede were predicted to occult a 7th-magnitude star on April 12, but Europa was not. Perhaps the plume did? Europa was slightly north of the Jupiter-Ganymede line of sight on that date, so that's what I'm betting on: That the plume was detected at a significant distance from Europa, perhaps even several Europa radii away.

However the evidence was gained, what could be unusual? The plumes could perhaps have been much more active than in the previous observations, occurring in more places other than the south polar region, or be much larger, or perhaps the composition reveals something more than what was seen last time. If it was that April 12 occultation, then the size of the plume would be part of the answer: It would be monstrous compared to the previous observations.

That's all the detective work I can muster until Monday.

[B Bernatchez]

Water plumes detected by Hubble: http://www.nasa.gov/press-release/nasa-s-h...ers-moon-europa

[Phil Stooke]

Hot from Twitter:

" Emily Lakdawalla Retweeted


Tanya Harrison ‏@tanyaofmars · 26m26 minutes ago

Britney Schmidt notes that the idea of plumes from #Europa was proposed during Galileo, but none found at the time. (1/2)"


Actually the first suggestion was based on a Voyager image of Europa - not widely believed at the time, but it was suggested.

----------------
Title: Active Venting of Europa?: Analysis of a Transient Bright Surface Feature
Authors: Helfenstein, S.-P. & Cook, A. F.
Journal: LUNAR AND PLANETARY SCIENCE XV, P. 354-355. Abstract.

Phil
(Hi Tanya!)

[Brian Burns]

Actually the first suggestion was based on a Voyager image of Europa - not widely believed at the time, but it was suggested.
----------------
Title: Active Venting of Europa?: Analysis of a Transient Bright Surface Feature
Authors: Helfenstein, S.-P. & Cook, A. F.
Journal: LUNAR AND PLANETARY SCIENCE XV, P. 354-355. Abstract.

That's really interesting - from the paper here (from 1984) - http://adsabs.harvard.edu/full/1984LPI....15..354H - they talk about the Voyager 2 image 20767.37 -



I can sort of make out a diffuse plume, but not a bright spot - do I have the right image? If so, needs enhancing! (this is the crummy jpeg preview version, and North is downwards)



From http://pds-rings-tools.seti.org/opus/#/pla...2_ISS_2076737_N

[JohnVV]

grabbed the image "c2076737.imq"



false color image

BUT the maybe spot is also aligned with the BRIGHT spot
i would call that optic scatter

[Brian Burns]

Hmm, interesting. The paper also compared the same region with an image taken 6 days prior, and found that the bright spot might have been new...

Business Insider has a good view of the recent plumes -



Hubble/NASA/STScI/Business Insider

From http://www.businessinsider.my/europa-water...e-photos-2016-9

[Decepticon]

Has a area on europa been narrowed down to the possible activity? I saw no mention of exact area that is thought to be active.

[JohnVV]

also see post #75 in this thread
http://www.unmannedspaceflight.com/index.p...st&p=207918

and the other image mentioned in the old paper you linked to "c2058143.imq "
there is a little something there but it dose look like tracking motion
-- false color

[Paolo]

by the way, the full paper of Hubble's observations is here: 91 Mb pdf

[climber]

Has a area on europa been narrowed down to the possible activity? I saw no mention of exact area that is thought to be active.

They talk of Conemara region