Rev 61 Enceladus (March 12 2008) Options

[Holder of the Tw...]

The mission description PDF is now online.

Enceladus 3 Flyby

[scalbers]

Yes, nice to see the imaging footprint details. The basemap has kind of a familiar look to it

Should be interesting to see some new areas being imaged at higher resolution than in previous encounters (both northern and southern).

[Adam]

I'm a bit confused about the what the highest resolution of the images will be. This description claims that the ISS will take images up to meter-scale, but I can swear on that I saw another description somewhere that said that the images taken will at most be 200 meters/pixel. While I guess that's technically meter scale I'd like confirmation on that.

[jasedm]

Adam, there's a more detailed mission description here that details the resolution of the NAC whether it's 'prime' or 'ride-along' throughout the encounter.

[john_s]

There's now a multi-person blog about the Enceladus encounter on the Cassini web site. Just three posts so far (including one from me ), but more will be posted soon.

John.

[Holder of the Tw...]

One of you guys on the Cassini team needs to please get ahold of the webmaster for the official Cassini site, and tell them that the date on the simulator (Where is Cassini now?) is out of whack.

Tried sending a discreet email this afternoon, but ...

[Guest_Sunspot_*]

Tried sending a discreet email this afternoon, but ...

Although there is a Contact Us/Feedback link on pretty much every NASA page, I've never had any feedback from any message/email i've ever sent.

[ugordan]

I kind of lost track of when the C/A distance was set to 50 km as opposed to the 38 km figure stated earlier. What were the reasons the altitude was raised?

Great idea on a blog, too. Looking forward to new entries!

[centsworth_II]

Great idea on a blog, too. Looking forward to new entries!

Although this one: Enceladus Approach Maneuver canceled
scared the heck out of me until I realized it referred to a correction
maneuver on the way to the Enceladus encounter.

[john_s]

Thanks for pointing out the problem with the "Where is Cassini Now?" page- I just sent in a note about it.

The close approach distance on Rev. 61 was raised due to a desire to be a little more cautious about the plume hazard, I believe. We'll review the plume data from this flyby in order to decide whether to maintain the planned 21 km approach distance on Rev. 88.

John.

[ugordan]

Whoa! 21 km? Talk about threading the needle there...

You've really got to admire the accuracy with which the navigation team's flying a spacecraft some 1.5 billion km away.

[Greg Hullender]

Technically speaking, we should admire it *after* the flyby. BEFORE the flyby, we can still admire their bravery though. :-)

--Greg

[ugordan]

Well, in all honesty, they've proven this time and time again. The most recent cancellation of the final targeting maneuver just shows how good a hold of the trajectory they really have.

[djellison]

I've never had any feedback from any message/email i've ever sent.

Well, I know for a fact that Alice Wessen (head of Cassini outreach) has personally attended to that very task until very recently, and it's now in someone elses hands. If you've got a specific case in point, let me know and I'll pass it on.

Dave 'the navigator' Seal is working on the simulator to get it sorted. There's server shifts and recompiles involved.

Doug

[ilbasso]

I always pray that they're remembering to aim 21 km above the SURFACE, not from the center!

[Holder of the Tw...]

Simulator is fixed!

Also got back a nice reply from the Cassini Team.

I assumed that it was something easy to fix, and therefore they were simply unaware. Turns out they were really dealing with some issues on it, and several people had emailed them.

Just in time for the flyby, too.

LINK

[Holder of the Tw...]

The first of many ...

March 9

March 10

[ugordan]

Turns out they were really dealing with some issues on it

I noticed that Cassini's cumulative trajectory plot is now significantly smoother. Looks like they decreased the time tick interval (at periapsis only?) by which they draw the trajectory using linear segments. It looked ugly at periapsis before because that's when the S/C covered the greatest distance per time unit. Also, I don't remember seeing anything else than Titan in the lower right view before. Neat.

[Holder of the Tw...]

According to the official blog on the JPL Cassini Huygens web site, the spacecraft has begun it's data download to the Deep Space Network. The download will take about nine hours.

[nprev]

Some flyby raws are up. Check this shot in particular. Those 'central mounds' in the larger craters are most intruiging!

[remcook]

beauty!
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=146107

[David]

beauty!
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=146107

Is all the snow just randomly "hot" pixels?

[ugordan]

beauty!
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=146107

Am I correct in assuming the illumination from the "bottom" is actually saturnshine primarily from the planet's southern nightside which, in turn is softly illuminated by reflected ringshine? See this image for an illustration, only in this case the rings would be nearly perfectly edge-on (not sure how much they contribute to lighting) and the sunlit crescent wouldn't be visible.

Also, the two additional illumination sources on the "top" side of the moon (seen in other, even longer exposure shots) would be two of the neighboring satellites?

David, the majority of those dots (actually short streaks) are stars.

[volcanopele]

The illumination from "below" is Saturn-shine (possibly ring shine...). The illuminator to the right is Tethys with some light from Dione (both are pretty much in the same direction). The illuminator to the lower left is Rhea.

[um3k]

Here's a mosaic (click for full size):

[ugordan]

The illumination from "below" is Saturn-shine (possibly ring shine...).

This would have to be a sort of ring-saturn-shine if that's what you meant, doubly reflected and dim light off of the cloud tops. Enceladus is in such a low inclination orbit, 0.019 deg (compared to Mimas' 1.51 deg) that the main rings are effectively invisible. I wonder how much light the broader F ring would diffuse and if it would be comparable in brightness to the light flux from the night side?

[ustrax]

CDA bad news...

[jasedm]

Nice work um3k, I was waiting to see which of the resident image wizards would come up trumps first on this north pole mosaic

[djellison]

CDA bad news...

End of : http://youtube.com/watch?v=7P2NMem2llQ





Doug

[elakdawalla]

The JPL website must be getting hammered...I'm having a hard time getting in to the raw images. Wish I could grab them and set up a mirror somehow...

--Emily

[ugordan]

The flyby blog appears to be down as well...

[brellis]

The JPL website must be getting hammered...I'm having a hard time getting in to the raw images. Wish I could grab them and set up a mirror somehow...

--Emily

I've decided to keep away from the NASA site, and just wait until somebody smart from UMSF has had a look at them.

[Stu]

I haven't been able to get a look at the raws since I came home from work, 3 hours ago...

Still, shouldn't complain, I guess; it's a sign that this fly-by has got a LOT of people out there intetrested in space exploration. We can't have it both ways!

Thanks to everyone who's posted images here. I'd have seen NOTHING otherwise!

[Stu]

Some quick "Hmmmm...."s... looking at um3k's excellent image...

1. What happened to the rest of these craters?
2. Ooh look, a "chevron" like on Miranda...!
3. Weird... re-frozen cryo-volcanoes..?

[Bjorn Jonsson]

The JPL website must be getting hammered...I'm having a hard time getting in to the raw images. Wish I could grab them and set up a mirror somehow...

I've seen only a single image so far. It's extremely slow with frequent errors. UMSF is extremely slow today as well (even slower than yesterday). I'm not sure I'll be able to post this message without errors ;-).

[stevesliva]

I find the TryAgain firefox plugin helps when sites are getting bombed:
https://addons.mozilla.org/en-US/firefox/addon/2462

Of course, that means I'm exacerbating the issue more than my share. But I'm selfish.

[marsbug]

Weird... re-frozen cryo-volcanoes..?

The crater to the upper left of the two marked seems to have something similar. It'll be interesting to see how many craters have this effect, and if its in anyway related to size.The image that pops into my head is a large impact producing a temporary lake of liquid water underneath it, which powers cryovolcanism.

[ugordan]

If I'm not mistaken, those two craters were apparent back in the Voyager imagery and led to various explanations like viscous relaxation of ice which (unlike other icy sats) seemed to be warmer and thus less rigid. Very few, if any of the craters on Enceladus have your typical crater-bowl-look seen on other worlds.

[Juramike]

The crater to the upper left of the two marked seems to have something similar. It'll be interesting to see how many craters have this effect, and if its in anyway related to size.The image that pops into my head is a large impact producing a temporary lake of liquid water underneath it, which powers cryovolcanism.

Or it punches through to a liquid layer and the open throat is the source for upwelling.

Just like the Evil eye of W Quivira or Coats Facula on Titan?

I can't wait to measure the ratio of inner diameter vs. rim diameter. It looks pretty similar.

-Mike

[mgrodzki]

wow… everything is real tied up. i guess nobody here has anything else from other sources?

[mgrodzki]

anyone find out if these dots are all “hot pixels” or otherwise?

Attached thumbnail(s)

 

[elakdawalla]

Gordan is right. Those distinctive Enceladan craters with up-domed floors, where the domes are heavily fractured, are very easy to explain through the process of "viscous relaxation," where the crater looked normal (bowl shaped or whatever) when it formed, but over time, and with help from heat conducting from the interior, gravity causes the ice in the crater to flow (in the solid state -- no volcanism or anything required here) to equalize the gravitational potential. Short-wavelength features take longer to relax because the strength of the ice comes in to play, so you get the most deformation acting on the longest wavelength, which is the up-down-up of the crater rim-floor-rim. As the floor domes upward, there are extensional stresses along the top of the dome, so it fractures. This is basically the same kind of stress regime that is being proposed to explain the "spider" feature in the center of Caloris as seen by MESSENGER on Mercury.

I looked around for some papers on viscous relaxation on Enceladus and this is what I came up with that's in the public domain.
http://www.lpi.usra.edu/meetings/icysat2007/pdf/6051.pdf
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/2237.pdf

Mgrodzki, as ugordan pointed out here, those are stars. It's a long exposure becuase of the eclipse.

--Emily

[mgrodzki]

anyone find out if these dots are all “hot pixels” or otherwise?

ah… i just saw emily’s post. its super-exposed from rings shine, saturn shine… etc. so those could very well be stars picked up by the sensitive exposure.

[Juramike]

I took um3k's image (Stu's annotation added) and zoomed in on "3":





Side by side comparison with the T25 RADAR image of the "Evil eye" W Quivira feature on Titan (annotated and unannotated versions). The ratio of inner bulge and outer rim diameter are real close, even though "Evil eye" feature on Titan is ca. 5x bigger.

The central domes look larger and a little bit rougher ("bulgier?") than normal. Topography would help illuminate this (that's a stretch for a "shape from shading" pun). Maybe these are central dome craters where the rebound just didn't know when to stop?

-Mike

[EDIT: Just saw Emily's post. Fracturing would make the central domes look rougher. Might also explain the Evil eye of Titan if it is indeed a fractured-up central dome crater.]

[elakdawalla]

Since these places have names, we might as well be using them. Stu's "3" is Aladdin. The adjacent, more angular-outlined one is Ali Baba. Here's the Voyager view:



--Emily

[Stu]

Still can't get on the raw images site... has anyone ever known a lock-out like this before? I can't remember having this much trouble getting at the Iapetus close fly-by images...

MAybe we just have to wait for every space enthusiast in the US with a computer to go to bed!

[elakdawalla]

It's unusual. I've exchanged emails with folks at JPL and they are working on the problem. They say that although it seems as though it's traffic-related, they've tested with much higher demand and not had problems, so it's a bit of a stumper.

FWIW, I do get pages to appear as long as I wait long enough.

--Emily

[Astro0]

A short animated version of the Enceladus approach from the raw images.

Enjoy
Astro0

[volcanopele]

Post-encounter press release
http://saturn.jpl.nasa.gov/news/press-rele....cfm?newsID=824

Three-image mosaic
http://ciclops.org/view.php?id=4865

[mgrodzki]

I thought some of the rough images would make a cool animation… especially (oddly enough) because of the motion blurry frames.

check it out: Plume Diving: The Approach

[mgrodzki]

actually… i should just upload it here. will animated gifs work here?

Attached thumbnail(s)

 

[Astro0]

mgrodzki, I think you need to run that backwards, I'm pretty sure this is the south polar departure view.
Cool website BTW.

Astro0

[mgrodzki]

mgrodzki, I think you need to run that backwards, I'm pretty sure this is the south polar departure view.
Cool website BTW.

Astro0

argh! 50-50 wrong everytime!

[mgrodzki]

mgrodzki, I think you need to run that backwards, I'm pretty sure this is the south polar departure view.
Cool website BTW.

weird. i revised, but in edit mode only one image embed is there yet 2 show up? anyway... the top one if corrected now.

[Spin0]

Hi all,

New member here - fist post :)
I made some colour composites of Cassini's raw images. You can see a hint of blue inside some the northern craters. It becomes more obvious when the image is oversaturated in a imageviewing/manipulation program.

Enceladus' north pole seen from ~91000 km.

Filters IR3, GRN, UV3 mapped to R, G and B.
Distance about 91000 km.
Raw-images: N00103753 - 55

The north pole closer - from about 65000 km.

Filters IR3, GRN, UV3, CL mapped to R, G, B and luminosity.
Distance about 65000 km.
Raw-images: N00103763 - 66

South pole area and some tiger stripes seen from about 130000 km.

Filters IR3, GRN, UV3, CL -> RGB+lum.
Distance about 130000 km
Raw-images: N00103775 - 78


I also compiled a flyby-video using the raw images, it's in Youtube: http://www.youtube.com/watch?v=l5PqLPU2VA4

Yay, first post!
Spin0

[jasedm]

Thanks for those spin0, and welcome.
It's useful to see the colour composites as they show the fresher ice more clearly in various features.
I liked your Iapetus flyby composite on youtube too - shows very well the frenetic activity of the cameras during that relatively slow flyby.

[dilo]

Welcome, spin0!
Great color images (I tried to make something similar with UV+Clean+IR of South Pole view, but your results are better!).
I suspect that blue/green features are actually SHADOWs of the plume, based on their position respect to tiger stripes fractures.
Any opinion on this?

PS: mgrodzki, your animations are stunning, bravo!

[ugordan]

I suspect that blue/green features are actually SHADOWs of the plume, based on their position respect to tiger stripes fractures.
Any opinion on this?

I have to disagree. It's the coarse ice within the fractures that has a different spectra (notably it's dark in the IR3 deep infrared filter, not particularly so in the IR1 filter) making them blue-green. The plumes are far too dilute to produce any shadowing, in fact they pretty much only scatter light, not block it. Notice there are blue-green fractures to the left as well, far from the pole where the outgassing happens.

BTW, nice work on color registration, Spin0! I think it's funny how the raw contrast stretch algorithm makes it appear Enceladus was illuminated with the usual "white" light from the Sun when in fact the light coming through was pretty yellow/brownish, depending on how much of the illumination is directly due to reflected ringshine. In particular, both the rings and Saturn are dark in the UV3 filter indicating the exposure required was long. And yet, no obvious blur can be seen in the narrow angle. Amazing.

[JRehling]

I like the departure/arrival movies! Reminds me of a Fritz Lang movie. German Expressionism meets space exploration.

[Guest_Sunspot_*]

Hmm I knew the CDA glitch would be focus of any post flyby news coverage.

Cassini probe failed to taste moons geysers in flyby

[centsworth_II]

"Cassini probe failed to 'taste' moon's geysers in flyby"

Sometimes I am disappointed in New Scientist's sensationalist headlines.
I guess they deserve to be compared to the Sun tabloid.

[vexgizmo]

And Slashdot has a similar wrong-headed take on this, based on the New Scientist article.

http://science.slashdot.org/science/08/03/14/1535236.shtml

Can someone with a Slashdot account go set them straight?

[volcanopele]

One of the CICLOPS folks did in the last comment. I'll probably respond to him.

[mgrodzki]

I like the departure/arrival movies! Reminds me of a Fritz Lang movie. German Expressionism meets space exploration.

totally. i did one with ted stryk’s mariner images to mars a while back too. same weird nickelodeon old tyme effect on space travel. i did “add” a few things to make it smooth. noted on my blog what those items were. essentially 3 frames added to a 10 frame animation.

[scalbers]

These are fun images to work on with my map, particularly the north polar ones. First though I see I'll want to retool some of the limb fitting routines to work better with triaxial ellipsoids in this type of polar view.

[tallbear]

CIRS should have the real PRIZE data from this flyby ....

mapping of the S Polar region while Enceladus was in eclipse ( no sunlight
to compete with the heat from the vents... )

Should be really interesting ..... but it's going to take them awhile
to get the reconstructed pointing info ....

T

[Bill Harris]

This flyby produced a real gem of science by "imaging" the vents with the CIRS when the room lights were off (eclipse). And the south polar region being illuminated by faint "saturn light" gives a secondary verification of the topography of the vents imaged.

I'd call the flyby planning brilliant.

--Bill

[Spin0]

Thank you all for the kind words of the images and the video I posted - and yes, it does bring Fritz Lang and Murnau to my mind too! :)

During the flyby Cassini took about ten color images of Enceladus (10? 11?). I composited nine of them using the raw images. Some of the following images I already posted earlier, these are new a little bit better versions done with some more care, I even bothered to erase most of the cosmic rays.
In all images filters IR3, GRN, UV3, CL -> RGB+luminance

Approach.
Dist.612000km, raw images:N00103726-29 Dist.316000km, raw images:N00103730-33

Dist.307000km, raw images:N00103734-37 Dist.225000km, raw images:N00103738-41

North pole.
Dist.91000km, raw images:N00103752-55 Upper and lower parts B&W. Dist.65000km, raw images:N00103763-66

Outbound. In these images reflected lights give a different tint on each side of the moon.
BTW: there's a bright blue-green spot near south pole. What is it? A mountain?
Dist.131000km, raw images:N00103775-78 Dist.144000km, raw images:N00103779-82

Dist.213000km, raw images:N00103793-96

[jasedm]

I'd call the flyby planning brilliant.

--Bill

I agree wholeheartedly - talk about maximising opportunities!
Many plaudits to those involved in the flyby design.

[tedstryk]

Since these places have names, we might as well be using them. Stu's "3" is Aladdin. The adjacent, more angular-outlined one is Ali Baba. Here's the Voyager view:

Here is the complete Voyager view (Emily's post contained one frame of a mosaic).

Ted

[belleraphon1]

All... NASA To Release New Details from Close Flyby of Saturn Moon

http://www.spaceref.com/news/viewpr.html?pid=25007

Wednesday the 26th press conference at 2:00pm EDT. On NASA TV http://www.nasa.gov/ntv

Craig

[Floyd]

Did anyone catch the The von Kármán Series Lecture webcast last night? Did Dr. Hendrix give hints of what will be in the press conference?
-Floyd

[scalbers]

Here's a first cut with some Rev 61 images now in the map (both northern and southern hemisphere).



The full resolution version is here:

http://laps.noaa.gov/albers/sos/sos.html#ENCELADUS

Enjoy,

Steve

[jasedm]

Thank you Steve - still the Web's best source for mapping information of this kind.

[Juramike]

News release of the Enceladus flyby. The plume is slightly warmer than expected and has organics!

Whoo-hoo!

Anyone have the list of the organics detected and the relative amounts?

http://saturn.jpl.nasa.gov/news/press-rele....cfm?newsID=827

-Mike

[EDIT: This would be the most expensive sparkling water ever tasted - and worth every penny!]

[Stu]

Anyone else here for the media briefing? Bring popcorn?

[ugordan]

I hate to break it to you, Stu, but it's already over

[Stu]

I hate to break it to you, Stu, but it's already over

Ah, got my times mixed up. Never mind. I'll look forward to reading up the results.

[Juramike]

The Tiger Stripes were found to be hot along most of their entire length. ("Hot" meaning ca. 100 K above the surface temperature)

NASA image release: http://photojournal.jpl.nasa.gov/catalog/PIA10361


And Chris McKay weighs in on the possibility of life on Enceladus: http://saturn.jpl.nasa.gov/news/features/feature20080326.cfm
(Spoiler alert: might coulda happened)

-Mike

[stewjack]

News release of the Enceladus flyby.

Anyone have the list of types of organics and their relative amounts?


-Mike

I saw about five minutes of what must have been a very short news conference. No audience questions. The only thing I remember was that all particles were very small which will allow the next Cassini pass through the plume to be at a lower altitude.

Jack

[ynyralmaen]

Ah, got my times mixed up ...

Yeah - one hour less time difference between the US and Europe for a few weeks, until we're on summer time too.

Anyone know if the conference will be posted online? I missed most of it - didn't realize there was a separate media channel until it was too late ;can't see any repeats listed.

[elakdawalla]

I hate that whole media channel thing. Stupid NASA. I missed most of the press conference myself, but fortunately I was able to catch up with John Spencer and Hunter Waite by phone, so I've got good stuff for an article later today -- stay tuned. Carolina Martinez told me that she was working on getting the press conference (maybe audio only, I am not sure) posted on the Enceladus flyby blog later today for the benefit of everyone who missed it. So check there and post here when it shows up!

I think the biggest news is that, compositionally, Enceladus looks like a comet, which is totally, completely baffling.

--Emily

[Juramike]

CICLOPS article on Enceladus' plume: http://ciclops.org

Composition of plumes compared to comets: http://photojournal.jpl.nasa.gov/catalog/PIA10357


And the INMS spectrum showing simple and "complex" organics (their definition of "complex" is very different than mine - we're not talking teterodotoxin here): http://photojournal.jpl.nasa.gov/catalog/PIA10356


(Dalton = amu; benzene is about m.w. 78)

From CICLOPS cpcomments:
"Also, it is now unambiguous that the jets emerging from the south polar
fractures contain organic materials heavier than simple methane --
acetylene, hydrogen cyanide, formaldehyde, propane, etc."

-Mike

[rlorenz]

From CICLOPS cpcomments:
"Also, it is now unambiguous that the jets emerging from the south polar
fractures contain organic materials heavier than simple methane --
acetylene, hydrogen cyanide, formaldehyde, propane, etc."

-Mike

As sparkling water goes, I am not sure I'd like the taste of this....

Ciclops' unsurprising gushing (!) notwithstanding, there are a few people
(e.g. Veronique Vuitton at the Titan Chemistry workshop here in Miami
http://www.chem.hawaii.edu/Bil301/Titan2007.html )
noting that some attention should be paid to possible chemistry on the
surfaces of the INMS instrument itself (e.g. during Titan flybys, benzene or
Phenyl (C6H5), cant remember which, peaks AFTER closest approach). In
other words could these 'Enceladus' organics be reaction products of
Enceladus water with Titan gunk on the inside of the instrument?

I personally doubt it, but wanted to note that 'unambiguous' is a
pretty heavy duty word for what may be a rather complex situation.

I guess I won't complain too much if a Titan Flagship does a little bit
of Enceladus science on the way, though. Looks not entirely uninteresting....

[JRehling]

could these 'Enceladus' organics be reaction products of
Enceladus water with Titan gunk on the inside of the instrument?

Panspermia in action. "Attack of the Saturn Beasties" sure to follow.

"Hey, you got your smog in my geyser."

[Juramike]

"Hey, you got your smog in my geyser."

Or: "Who Plugged the Probe?"

[ectoterrestrial]

Missed the NTV briefing.

Looking at the following graph with mystery vertical axes:
MassSpec graph at PhotoJournal

I'm wondering if there's some nitrogen hiding in there. The lack of a large NO2 peak could be diagnostic of it's overall absence, but theres plenty of curve under which N2 and NO could be hiding, as well as some in the "simple" and "complex" organics.
Also, NH3 and fragments thereof at 17 AMU.

Does anyone know why 1) little nitrogen is inferred from the data or 2) when a published paper with these results will be available?

[DFortes]

Can I please caution peeps about the 'comet' comment

Which comet? Compositionally, comets appear to be extremely heterogeneous.

Secondly, observational planetary science should always avoid any labels that carry some kind of genetic connotation (since they're invariably wrong). So, if it barks like a comet, it's a comet?
Oh, metaphor god, strike me down.
For example, you can call a bunch of squiggles a dendritic pattern, but not a channel network (since it implies formation by fluid flow, whereas dendritic is purely descriptive) - unless you're pretty sure it's a channel network.

There are other ways to make heavier organics.

I'm loving these new data - the CIRS stuff is beautiful. I'd like to know how the shear heating bods feel about these results....

[jasedm]

Very interesting that the sulci hot spots are very noticeably parallel - why might this be???

[Juramike]

"Simple" organics = 1C + heteroatom [N or O] or 2C + associated hydrogens

"Complex" organics = 2C + heteroatom [N or O] or 3C + associated hydrogens

Propane m.w. 44
Ethanol ("moonshine" ) CH3CH2OH m.w. 46

Note that methanethiol (CH3SH) is a whopping 48 amu and was not detected by INMS

(but acetonitrile CH3CN (m.w. 41) , could be a "complex" organics consituent)

-Mike

[jasedm]

I'm ashamed in the presence of you chemists.

[Juramike]

space.com article on Enceladus is out: http://www.space.com/scienceastronomy/0803...yby-update.html

-Mike

[volcanopele]

For those who missed the press briefing:

http://www.jpl.nasa.gov/news/cassini20080326.cfm

[Juramike]

Emily's article regarding today's briefing on Enceladus: http://planetary.org/news/2008/0326_Cassin...tes_Like_a.html

Nicely written, Emily!

-Mike

[nprev]

You got that right, Mike. Superb work, Emily, written in such a way that even a humble artificial intelligence such as myself can understand it all!

The cometary compositional similarity is interesting. Almost begs the question of whether something unexpected (heating) happened to them rather then something funny about Enceladus. I can't see any possibility of Enceladus being a captured body.

[Holder of the Tw...]

I would dearly love to see some 10m resolution (or better!) NAC photos of the hottest areas of those tiger stripes, along with the WAC context shots. I know they plan some high resolution views in the next flyby, but I haven't yet read just how high the resolution will be. Hope their plans for the next flyby work. The 15 year night cometh soon.

[CosmicRocker]

Can one of you astrobiololgy or icy body chemical types comment? I read the headlines noting the discovery of "complex organics," but the published spectrograph displays the heaviest broad peak centering around 40 Daltons. I wouldn't normally describe molecules of this weight range as "complex."

Are molecules heavier than the C2/CN/CO range typically considered complex by space scientists?

I noted that Emily's blog entry stated that "At higher masses, not shown on the graph above, "we saw more complex compounds, like propyne, propane, maybe even acetonitrile, and then we saw things even more complex. But they were so weak in signal that we didn't venture an identification." Propane and propyne should have appeared on that graph, since its X-axis goes up to 50 Daltons. Was that data simply erased from the publically released spectrograph?

[JRehling]

The cometary compositional similarity is interesting. Almost begs the question of whether something unexpected (heating) happened to them rather then something funny about Enceladus. I can't see any possibility of Enceladus being a captured body.

Yeah, is what we're seeing between comets and Enceladus anything but ices + one-time heating to drive a little chemistry? It doesn't look to me any more remarkable than the fact that SiO2 exists in the rocks of Earth, Moon, and Mars or that N2 exists in the atmospheres of Venus, Earth, and Mars. You put the same elements together, and you usually get the same compounds.

[DFortes]

Yeah, is what we're seeing between comets and Enceladus anything but ices + one-time heating to drive a little chemistry? It doesn't look to me any more remarkable than the fact that SiO2 exists in the rocks of Earth, Moon, and Mars or that N2 exists in the atmospheres of Venus, Earth, and Mars. You put the same elements together, and you usually get the same compounds.

Exactly - thankyou.

My view is that the 'comet' label - whether it was meant to or not - connotes some suggestion that the organics are primordial. However, the heat flux and plume activity strongly suggest active chemical synthesis (a la Matson), which (to my feeble mind) is more astrobiologically interesting.

[nprev]

I would dearly love to see some 10m resolution (or better!) NAC photos of the hottest areas of those tiger stripes...

My thoughts exactly. I strongly suspect that the emission areas are very localized, extremely narrow, and MUCH warmer than their immediate surroundings, which are presumably experiencing secondary heating... the actual vents have temps certainly exceeding 273 deg K.