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Unmanned Spaceflight.com _ Jupiter _ Europa PR

Posted by: JRehling Dec 20 2007, 09:26 PM

Thick or Thin Ice Shell on Europa?
http://photojournal.jpl.nasa.gov/catalog/PIA10131

Europa Tide Movie
http://photojournal.jpl.nasa.gov/catalog/PIA10149

I'm not sure that there is any new science involved. Seems to me like some nice eye candy for the purpose of getting Europa into the collective consciousness before the next flagship is chosen.

Posted by: volcanopele Dec 20 2007, 09:58 PM

Bah, blatent Europan propaganda ph34r.gif mad.gif It's all rigged I tell ya.

laugh.gif

Posted by: Decepticon Dec 20 2007, 10:08 PM

Excellent!

Thin all the way baby!

Posted by: ugordan Dec 20 2007, 10:10 PM

QUOTE (Decepticon @ Dec 20 2007, 11:08 PM) *
Thin all the way baby!

So it's thin ice all the way down? biggrin.gif

Posted by: nprev Dec 20 2007, 10:17 PM

QUOTE (volcanopele @ Dec 20 2007, 01:58 PM) *
Bah, blatent Europan propaganda ph34r.gif mad.gif It's all rigged I tell ya.

laugh.gif


Clearly, the Europans have found themselves a very good agent...given the current Hollywood Writer's Guild strike, I'm sure that there's a few on the market! tongue.gif

Posted by: Mariner9 Dec 21 2007, 09:23 PM

QUOTE (volcanopele @ Dec 20 2007, 01:58 PM) *
Bah, blatent Europan propaganda



I feel your pain. It's been a mystery to me why Io gets so little attention It's the most geologically active world in our solar system for Pete's sake.

When NASA announced they were studying outer planets moon missions, the four names that keep coming up are Titan, Europa, Ganymede and Enceladus. First in the "what can you get with a billion dollar mission" studies, and then the "well, fine, what do you get for 3 billion?"


Turns out you couldn't do much of anything worthwile with a billion dollars for the listed targets, but I'd wager you could get a lot of bang for your buck if you asked the same question about Io missions.

Posted by: dvandorn Dec 21 2007, 09:46 PM

Io is just a whole order of magnitude more difficult to do, in-close. The radiation environment there is extraordinary. The surface conditions on most of the globe are straight from Dante's Inferno. Orbiters and landers would be fried extremely fast.

You almost have to do your Io science from something of a distance.

-the other Doug

Posted by: volcanopele Dec 21 2007, 09:55 PM

No you just have a Jupiter orbiter make repeated flybys, and I would imagine it could be done more cheaply than some of these flagship mission. In fact, the one good thing going for a Europa mission, IMHO, is that it could be used to test a lot of rad-hard technologies needed for an Io mission wink.gif

Posted by: nprev Dec 21 2007, 10:03 PM

laugh.gif ...VP, you stick to your guns no matter what!!! Attaboy; give 'em hell! smile.gif

Posted by: JRehling Dec 21 2007, 11:12 PM

Incidentally, I think on the first one, they got the apparent motion of Jupiter completely backwards while moreover depicting Jupiter as tidally locked WRT the Sun (or somehow otherwise rotating other than the way it actually does).

Posted by: Mariner9 Dec 22 2007, 02:45 AM

QUOTE (dvandorn @ Dec 21 2007, 01:46 PM) *
Io is just a whole order of magnitude more difficult to do, in-close. The radiation environment there is extraordinary. The surface conditions on most of the globe are straight from Dante's Inferno. Orbiters and landers would be fried extremely fast.
-the other Doug



I agree that doing an Io Orbiter or lander would be really expensive. And the science payload on something like JSO is also very heavy and very expensive.

I was specifially reffering to the Billion Dollar mission class.... essentially a bit of a beefed up New Frontiers budget. For that price you could reasonably do a three axis stabilzed, moderately instrumented probe. Put it into a highly elliptical orbit and make repeated encounters. A single such flyby would return more data than Galileo did over it's entire mission. Even if the probe's electronics can only handle 10-20 flybys (which is roughly what Juno is designed for, IIRC) that is a hell of a science return.

I keep hoping Europe would step up to that plate, see a chance to do some exciting science that the US wasn't interested in. Unfortunately they appear to have been hi-jacked by the Europa Mafia.
They are also looking for partners. If that results in us somehow managing to afford both Titan and a Europa mission in the next 20 years, horay.

Otherwise.... shame they didn't jump at Io while we were engaged elsewhere. Or at just about anything in the outer planets... there are so many lonely targets out there. Bare Bones Uranian Orbiter anyone? Anyone?

Posted by: vjkane Dec 22 2007, 04:54 PM

QUOTE (Mariner9 @ Dec 22 2007, 02:45 AM) *
I was specifially reffering to the Billion Dollar mission class.... essentially a bit of a beefed up New Frontiers budget. For that price you could reasonably do a three axis stabilzed, moderately instrumented probe. Put it into a highly elliptical orbit and make repeated encounters. A single such flyby would return more data than Galileo did over it's entire mission. Even if the probe's electronics can only handle 10-20 flybys (which is roughly what Juno is designed for, IIRC) that is a hell of a science return.


If if I remember the JSO report, they concluded that another Galileo-style orbiter would add enough understanding of the Galilean moons to be useful. An orbiter would be needed to get at the next level of questions. The EE report explicitly states that the key questions for Europa cannot be answered with flybys.

I personally disagree. Not only did Galileo have very limited data return, its instruments were vintage 1975ish. Flying modern instruments would tell us a lot more. What would be lost for Europa would be the ability, as I read the report, to really nail down where to send a lander. Since the first lander will be able to study only the surface and near sub-surface, its really important to know where the surface has most likely interacted recently with the deeper subsurface. Also, it's essential to understand the terrain at ~1m scales to characterize lander safety issues.

As for the cost of a Galileo repeat, I think that if it goes into the inner Jovian system, it may not fit within the budget of a New Frontiers. Juno fills the budget, doesn't have radioisotope power sources, and has modest radiation hardening. A Galileo repeat would have all those. A craft that stayed out near Ganymede with maybe a few Europa flybys might avoid the need for these budget busting features. It could also have even a larger camera than what JSO is proposed to carry for remote studies of Io (which I find fascinating).

My emerging view is that the Jovian system is important to understand -- it seems to be a common planetary type around other stars. I think that a modest Galieo- style orbiter combined with a much less capable Europa orbiter a la the ESA makes sense as the next step. Studying that system, though, is just too hard because of the radiation and landers on Europa in interesting places is likely to be really hard -- there's lots of rough terrain. So I'd keep my investments in Jovian craft modest. And then I'd put my big money into Titan where the moon is endlessly fascinating, there's no radiation, and a wonderful atmosphere to simplify landing or floating about.

Posted by: Mariner9 Dec 23 2007, 12:00 AM

vjkane - Well stated, and I don't disagree with any of your points.


Basically, I just wanted to let Volcanopele know he is not a lone voice in the wilderness. Others of us have wondered why Io never even gets a passing mention.

Posted by: vjkane Dec 23 2007, 03:23 AM

QUOTE (Mariner9 @ Dec 23 2007, 12:00 AM) *
Basically, I just wanted to let Volcanopele know he is not a lone voice in the wilderness. Others of us have wondered why Io never even gets a passing mention.

I find Io endlessly fascinating. Given the incredible difficulty of any intense study of any single moon, I'd put my money into a mission that studies the differences. Yes, it is a Galileo repeat, but MRO is a Viking orbiter repeat in the same sense.

In depth studies of any single moon, though, is just too hard. If we find a good location on Europa, can we afford a lander to follow up? Can we even technologically implement it?

Titan is as interesting as any Jovian moon and much easier to access.

But I really want that Galileo follow on, too!

Posted by: DrShank Jan 11 2008, 03:33 AM

sorry to disappoint you thin-skinned, er i mean thin-shelled people. europas shell is thick, at least 10 more likely 20 km.
the smoking gun is the topography. there are places with 1 kilometer of relief in very short distances. one such scarp has a slope of around 30 degrees. a shell only a few kilometers thick simply cant generate or support such a large topographic height.

"my pontification, which is mine"

Posted by: Greg Hullender Jan 11 2008, 04:09 AM

Any thoughts as to what the minimum thickness might be? After all, Earth's crust is pretty thick too, but it does have its thin spots.

--Greg

Posted by: rlorenz Jan 11 2008, 03:57 PM

QUOTE (Greg Hullender @ Jan 10 2008, 11:09 PM) *
Any thoughts as to what the minimum thickness might be? After all, Earth's crust is pretty thick too, but it does have its thin spots.

--Greg



Zibi Turtle's finite-element modeling of crater collapse said
the crust had to be '14km minimum' IIRC
(at the location and time of crater formation)

Dr Shank's depth/diameter analysis I think pointed in a similar direction (see also his earlier
post about scarps)

Posted by: JRehling Jan 12 2008, 07:57 AM

Ice will not sustain major deviations in thickness for long spans of time, but I think the critical issue is if it can sustain them for a short time. Either a rift or a hot spot (which could mean a plume of slushy ice, or actually water welling up to or near the surface). I think the whole ballgame with Europa is to see if there's a place like that. If so, a submarine is possible. If not, we're stuck with the top few meters to explore.

I think the dark lineation along the triple bands is an indication that water gushed out along a huge number of tremendously long faults. Given the surface age of Europa, that translates into a considerable amount of active fault per year. The trick is whether you get about that much fault all the time, or if you have none at a typical moment, then occasionally much more activity takes place.

But we don't need an actual gusher -- just a place where the 20 km depth has been considerably reduced.

Posted by: vexgizmo Feb 10 2008, 04:45 PM

QUOTE (JRehling @ Dec 21 2007, 05:12 PM) *
Incidentally, I think on the first one, they got the apparent motion of Jupiter completely backwards while moreover depicting Jupiter as tidally locked WRT the Sun (or somehow otherwise rotating other than the way it actually does).

The goal was for Jupiter's rotation not to distract from the message, so Jupiter was not rotating at all. Riding along with Europa but with Jupiter not rotating unfortunately gave the false impression that Jupiter was rotating backwards.

This graphic has now been revised showing Jupiter rotating, alleviating this problem, but rotating much slower than actual speed, as to not be overly distracting.
http://photojournal.jpl.nasa.gov/catalog/PIA10149?

Thanks for the feedback!

Posted by: JRehling Feb 11 2008, 06:34 PM

QUOTE (vexgizmo @ Feb 10 2008, 08:45 AM) *
The goal was for Jupiter's rotation not to distract from the message


Probably for most people it didn't. But I'm the kind of guy who whispers to the person next to me in the movie theatre if the sun appears too high in the sky for the latitude and season that a scene is set in, or if the sun is on the left of someone who is supposedly driving east in the northern hemisphere. I'm glad that for one, my pedantry had an impact!

Posted by: belleraphon1 Nov 15 2011, 09:45 PM

NASA Hosting Science Update about Jupiter's Icy Moon Europa
http://www.spaceref.com/news/viewpr.html?pid=35229

NASA will host a Science Update at 1 p.m. EST on Wednesday, Nov. 16, to discuss new theories concerning Jupiter's icy moon Europa. The event will be in NASA's James E. Webb Auditorium at 300 E St. SW in Washington.

NASA Television and the agency's website will broadcast the event live. Reporters may attend the event or ask questions from participating NASA centers or by phone. For dial-in information, reporters must contact Dwayne Brown at: dwayne.c.brown@nasa.gov with their name, media affiliation and telephone number by noon Wednesday.

Europa, which is slightly smaller than Earth's moon, is thought to have an iron core, a rocky mantle and an ocean of salty water beneath its frozen surface.

Briefing participants are:

- Britney Schmidt, postdoctoral fellow, Institute for Geophysics, University of Texas at Austin
- Tori Hoehler, astrobiologist and senior research scientist, NASA's Ames Research Center, Moffett Field, Calif.
- Louise Prockter, planetary scientist, Johns Hopkins University Applied Physics Laboratory, Laurel, Md.
- Tom Wagner, program scientist, cryospheric sciences, Earth Science Division, NASA Headquarters

For NASA TV streaming video, scheduling and downlink information, visit: http://www.nasa.gov/ntv

For more information about NASA and agency programs, visit: http://www.nasa.gov



Posted by: antipode Nov 16 2011, 03:51 AM

Lets see, no current assets in Jupiter space, so this either has to be something derived from old spacecraft data, or something derived from current telescopic studies (or a combination of both).

I'd love to see evidence of venting of volatiles from one of those long cycloid cracks a la Enceladus, but...

Any ideas?

P




Posted by: nprev Nov 16 2011, 05:06 AM

I'm not reading this as a brief on new results; seems more like a presentation of new theories on the subsurface.

Posted by: DrShank Nov 16 2011, 06:16 PM

Getting at the ice shell thickness has been a real problem. All our evidence is circumstantial. But there are mountains a kilometer
high and
basins a kilometer deep. the surface is warped and the craters need to get very large before they start to penetrate near the bottom.
all these things point to a thicker ice shell, likely a minimum of 10 km, possibly as much as 20 km.

Posted by: belleraphon1 Nov 16 2011, 06:37 PM

Really is a conundrum... to me. I just wonder how you get enough energy from warm (hot) water plumes in the underlying ocean to penetrate through kilometers of steel hard ice. Yet the topography demands a thick ice shell.

Cool problem smile.gif


Posted by: DrShank Nov 16 2011, 06:51 PM

agreed. the new model and even the diapir model rely on warm ice from the base of the shell rising upward in a dome, like porridge boiling on a stove. water plumes melting through this thick ice is very difficult indeed, but doing it within the shell, thats easy(ier)

Posted by: belleraphon1 Nov 16 2011, 06:58 PM

So we are still talking plumes of warm ice... even in this new model. Yet the matrix looks like it needs melted ice (water) to explain the chaos. I am probably missing something. Are we talking a mechanism that lets melt (water) migrate to the top? Guess I really need to read the paper!

Thanks Dr Shank!

Posted by: DrShank Nov 16 2011, 07:02 PM

its a difficult concept even for me, but the rising plume changes the conditions of the ice over it. melting is a function of pressure as well as Temp,
and this causes a zone of ice to melt over the plume. yes it all takes place within the shell itself

Posted by: belleraphon1 Nov 16 2011, 07:13 PM

Interesting. And I guess there are chemical condistons relating to the saltiness and other constiuents in the melt (sulpuric acid, etc). And in the top icy layer pelted with Io
breath (sulphur).

Nature sets up grand experiments...

Thanks again!

Posted by: Paolo Nov 16 2011, 07:14 PM

for the lucky few having access to Nature, the paper is here:
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature10608.html

Posted by: ngunn Nov 16 2011, 07:49 PM

QUOTE (Paolo @ Nov 16 2011, 07:14 PM) *
the lucky few


I'm not one of the few, but I have now just skimmed through the paper's (freely available) supplementary material and having a personal fascination with subglacial hydrology I found it most interesting and informative. Thanks for the link. smile.gif

Posted by: stevesliva Nov 16 2011, 08:31 PM

Again reminds me of sandstone over salt domes. The salt is deformable and causes some interesting chaos in the stone.

Posted by: stevesliva Nov 17 2011, 01:22 AM

Article at NASA here links to larger versions of the Nature figures at UT:
http://science.nasa.gov/science-news/science-at-nasa/2011/16nov_europa/

Posted by: antipode Nov 18 2011, 02:55 AM

Okay, I have a question (it may be dealt with in the paper, I don't know)

I assume this mechanism can explain the dark staining of the chaos regions, but what about the dark staining of many of the long cycloid cracks? Doesn't this assume that there HAS been a connection between the (presumably) deep ocean and the surface at some stage in the fairly recent geological past? One that doesn't need the upwelling mantle plume/subsurface lake mechanism to communicate with the surface?

Could there be regions of deep AND shallow ice? Can Jupiter's tides crack those errr cracks all the way to their ocean bases, or is there another mechanism that could bring those stains (are they tholins?) to the surface?

P

Posted by: elakdawalla Nov 18 2011, 02:57 AM

They don't mention cycloids at all in the paper -- it's a modeling paper that only deals with chaos. So the paper doesn't address that at all. I'm curious to know the answer too!

Posted by: Juramike Nov 18 2011, 02:58 AM

(Don't think they are tholins, more likely salts or other stains from water-soluble materials)

Posted by: antipode Nov 18 2011, 04:00 AM

QUOTE (Juramike @ Nov 18 2011, 01:28 PM) *
(Don't think they are tholins, more likely salts or other stains from water-soluble materials)


Ah yes thanks mike, that would make a lot more sense. Where would the tholins come from?

P

Posted by: Explorer1 Nov 18 2011, 07:05 AM

Just a quick related question; how much do we know about Europa's rocky core and whether it is uneven in depth? I.e could there be places that it makes direct contact with the ice shell, without intervening water? Would an orbiter have to map it or could there be surface signs of these areas?

Posted by: Juramike Nov 18 2011, 12:03 PM

QUOTE (antipode @ Nov 17 2011, 11:00 PM) *
Where would the tholins come from?


Tholins form from irradiation and zapping of mixes of methane and nitrogen. If tholins are forming on Europa, it would be from zapping of small organics encapsulated in the ices as clathrates. I'm not saying it's not possible that the stains are organic molecules, but my first suspect would be salts from below.

EDIT: yup, the dark stuff is consistent with hydrated sulfuric acid.

See:
Shirley et al. EPSC 2011, 6, (freely availalbe): http://meetingorganizer.copernicus.org/EPSC-DPS2011/EPSC-DPS2011-1201.pdf

and (pay for article, abstract here): Orlando et al., Icarus 177 (2005) 528-533. http://www.sciencedirect.com/science/article/pii/S0019103505001983

Posted by: Gsnorgathon Nov 18 2011, 03:26 PM

QUOTE (Explorer1 @ Nov 17 2011, 11:05 PM) *
Just a quick related question; how much do we know about Europa's rocky core and whether it is uneven in depth? I.e could there be places that it makes direct contact with the ice shell, without intervening water? Would an orbiter have to map it or could there be surface signs of these areas?

Short answer, no.

Given that the estimates for the depth of Europa's ocean are about 100km, it's extremely unlikely that the rocky crust would come anywhere near the ice shell. Total relief on the moon (Earth's moon, Luna) is about 22-23km IIRC, and the moon's got a much stiffer and thicker crust since it's so cold. Since Europa's geologically active, I'd expect it to have a warmer and softer crust that wouldn't be able to support as much relief. I'd guess the highest point on the crust is ~90km below the surface of the ice.

Posted by: eoincampbell Nov 18 2011, 03:38 PM

QUOTE (Gsnorgathon @ Nov 18 2011, 08:26 AM) *
... it's extremely unlikely that the rocky crust would come anywhere near the ice shell...


But how are the purported "shallow lakes" forming in the first place?

Posted by: Phil Stooke Nov 18 2011, 03:46 PM

"But how are the purported "shallow lakes" forming in the first place?"

Read this for an answer:

http://www.skyandtelescope.com/news/Subsurface-Lakes-Explain-Europas-Terrain-134059133.html


There have also been suggestions that the chaos areas form over deep hot water plumes in the ocean, which in turn form over ocean floor volcanic eruptions, but modelling might not allow that. I haven't seen it tested.

Phil


Posted by: Floyd Nov 29 2011, 10:16 PM

The Nature article is quite nice (I'm one of the lucky subscribers). Is there a chance that some of the chaos terrain on Enceladus results from the same mechanism?


floyd
contact fdewhirst at forsyth dot org

Posted by: Phil Stooke Nov 29 2011, 11:06 PM

There is nothing comparable on Enceladus. Totally different geology. There might be areas you could call chaotic if you wanted to but they are very different.

Phil

Posted by: MarcF Mar 9 2013, 04:02 PM

Some new stuff from Europa:
"Based on new data from the W. M. Keck Observatory about Jupiter's moon Europa, astronomers hypothesize that chloride salts bubble up from the icy moon's global liquid ocean and reach the frozen surface where they are bombarded with sulfur from volcanoes on Jupiter's largest moon, Io."

Read more at:
http://phys.org/news/2013-03-astronomers-window-europa-ocean.html#jCp

Posted by: stevesliva Mar 9 2013, 04:56 PM

http://www.mikebrownsplanets.com/2013/03/sea-salt-part-1.html
http://www.planetary.org/blogs/guest-blogs/2013/0305-brown-sea-salt.html

Posted by: MarcF Mar 9 2013, 06:54 PM

Really nice explanations from Mike Brown !
BTW, lets dream a little bit:
http://www.youtube.com/watch?feature=player_embedded&v=e6d9P7F5Px8

Posted by: MarcF Mar 13 2013, 09:52 PM

I just heard about the Europa Clipper mission:
http://www.guardian.co.uk/science/2013/feb/15/nasa-europa-clipper-mission-jupiter-moon
http://themeridianijournal.com/2013/01/new-clipper-mission-proposed-to-study-europas-ocean/
It's not funded yet and I'm probably very naive and too optimistic, but hope dies the last. So who knows, maybe a NASA mission to Europa in the ten coming years !
Marc.

Posted by: MarcF May 9 2013, 10:44 AM

Where are the Best Windows Into Europa's Interior?
http://www.jpl.nasa.gov/news/news.php?release=2013-134
Marc.

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