[X] My Assistant

[paxdan]

Nasa Watch is reporting that we shoud expect a large announcement from the Cassini team today:

My wild speculation is that it will be a subsurface ocean confirmed on enceladus. Hence more potentially habitable real eastate in the solar system.

Heads up anyone?

[Guest_AlexBlackwell_*]

Note that NASAWatch/Spaceref is in its "breaking news" speculation mode regarding a "big" or "huge" announcement today.

Frankly, it looks as if Cowing just picked up on the toms-toms beating about the publication of the March 10, 2006, issue of Science, which is a special issue (Cassini at Enceladus).

[Guest_AlexBlackwell_*]

Note to whoever merged the two threads: If possible, perhaps you should move my post to the top; it makes sense given the topic title. Or you can change the topic title to match paxdan's message.

[JRehling]

Note that NASAWatch/Spaceref is in its "breaking news" speculation mode regarding a "big" or "huge" announcement today.

Frankly, it looks as if Cowing just picked up on the toms-toms beating about the publication of the March 10, 2006, issue of Science, which is a special issue (Cassini at Enceladus).

The media at large has picked this up, it is an announcement of subsurface liquid H2O at Enceladus, which seems to be a "no news" consequence of the jets imaged months ago. It's something if a place as profoundly obscure as Enceladus could become part of the vocabulary of the New Yorker set, if not a household name.

I don't, again, see this as news anymore, but it's a time to reflect that the Saturn system has definitely KOed the Galileans in terms of interest. Enceladus alone is almost a combination of Ganymede (old crust and new), Europa (subsurface ocean), and Io (volcanic plumes) in one. Then there's Titan. Wow.

Enceladus is still in the running for a high-priority flagship mission, although I don't know if it has the potential to climb to the top of that list among outer satellites.

[brachiopod]

FYI, "drudge" is reporting that they will announce liquid water on Enceladus. See
http://www.drudgereport.com/flash8na.htm
-Bryan

[helvick]

FYI, "drudge" is reporting that they will announce liquid water on Enceladus. See
http://www.drudgereport.com/flash8na.htm
-Bryan

Hey John Spencer (john_s) is quoted in this - any chance you can confirm this?

[Guest_AlexBlackwell_*]

FYI, "drudge" is reporting that they will announce liquid water on Enceladus. See
http://www.drudgereport.com/flash8na.htm
-Bryan

One has to chuckle at Cowing's journalistic standards, viz., "The Drudge Report has this story (and the press release) as their ultra- top news flash - above Condi and Iran. If *he* thinks this is more important (or at least of near-equal billing) than those issues..."

[Guest_paulanderson_*]

I don't, again, see this as news anymore, but it's a time to reflect that the Saturn system has definitely KOed the Galileans in terms of interest. Enceladus alone is almost a combination of Ganymede (old crust and new), Europa (subsurface ocean), and Io (volcanic plumes) in one. Then there's Titan. Wow.

I would certainly call this (big) news, even though we knew about the plumes already, because various theories were being considered to explain the plumes, the most interesting of which, but difficult to figure out the possible mechanisms of, was subsurface liquid water. Now it sounds like the Cassini team has settled on that explanation, and perhaps the water would be fairly close to the surface? Like a second Europa, but with active geysers... I'll be watching with interest!

[Guest_AlexBlackwell_*]

I would certainly call this (big) news, even though we knew about the plumes already, because various theories were being considered to explain the plumes, the most interesting of which, but difficult to figure out the possible mechanisms of, was subsurface liquid water. Now it sounds like the Cassini team has settled on that explanation, and perhaps the water would be fairly close to the surface? Like a second Europa, but with active geysers... I'll be watching with interest!

I think the point John Rehling was making was that for those us who closely follow these types of things, the news isn't as momentous as for someone who, for instance, might say, "Enceladus. Isn't that the name of that new car model?"

[volcanopele]

The Enceladus would make a good name for a car that runs on water...

*ducks*

[Guest_paulanderson_*]

I think the point John Rehling was making was that for those us who closely follow these types of things, the news isn't as momentous as for someone who, for instance, might say, "Enceladus. Isn't that the name of that new car model?"

Very true. And here I thought it was a new car model...

[Guest_AlexBlackwell_*]

Cassini Finds Signs of Liquid Water on Saturn's Moon
By Tariq Malik
Staff Writer, Space.com
posted: 09 March 2006
12:57 pm ET

[elakdawalla]

JPL's release is out via email, but it hasn't made it to their website yet, so I'll post it here.

NEWS RELEASE: 2006-033 March 9, 2006

NASA'S CASSINI DISCOVERS POTENTIAL LIQUID WATER ON ENCELADUS

NASA's Cassini spacecraft may have found evidence of liquid water reservoirs that erupt in Yellowstone-like geysers on Saturn's moon Enceladus. The rare occurrence of liquid water so near the surface raises many new questions about the mysterious moon.

"We realize that this is a radical conclusion -- that we may have evidence for liquid water within a body so small and so cold," said Dr. Carolyn Porco, Cassini imaging team leader at Space Science Institute, Boulder, Colo. "However, if we are right, we have significantly broadened the diversity of solar system environments where we might possibly have conditions suitable for living organisms."

High-resolution Cassini images show icy jets and towering plumes ejecting large quantities of particles at high speed. Scientists examined several models to explain the process. They ruled out the idea that the particles are produced by or blown off the moon's surface by vapor created when warm water ice converts to a gas. Instead, scientists have found evidence for a much more exciting possibility -- the jets might be erupting from near-surface pockets of liquid water above 0 degrees Celsius (32 degrees Fahrenheit), like cold versions of the Old Faithful geyser in Yellowstone.

Mission scientists report these and other Enceladus findings in this week's issue of Science.

"We previously knew of at most three places where active volcanism exists: Jupiter's moon Io, Earth, and possibly Neptune's moon Triton. Cassini changed all that, making Enceladus the latest member of this very exclusive club, and one of the most exciting places in the solar system," said Dr. John Spencer, Cassini scientist, Southwest Research Institute, Boulder, Colo.

"Other moons in the solar system have liquid-water oceans covered by kilometers of icy crust," said Dr. Andrew Ingersoll, imaging team member and atmospheric scientist at the California Institute of Technology, Pasadena, Calif. "What's different here is that pockets of liquid water may be no more than tens of meters below the surface."

Other unexplained oddities now make sense. "As Cassini approached Saturn, we discovered that the Saturnian system is filled with oxygen atoms. At the time we had no idea where the oxygen was coming from," said Dr. Candy Hansen, Cassini scientist at NASA's Jet Propulsion Laboratory in Pasadena. "Now we know that Enceladus is spewing out water molecules, which break down into oxygen and hydrogen."

Scientists are also seeing variability at Enceladus. "Even when Cassini is not flying close to Enceladus, we can detect that the plume's activity has been changing through its varying effects on the soup of electrically-charged particles that flow past the moon," said Dr. Geraint H. Jones, Cassini scientist, magnetospheric imaging instrument, Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany.

Scientists still have many questions. Why is Enceladus currently so active? Are other sites on Enceladus active? Might this activity have been continuous enough over the moon's history for life to have had a chance to take hold in the moon's interior?

"Our search for liquid water has taken a new turn. The type of evidence for liquid water on Enceladus is very different from what we've seen at Jupiter's moon Europa. On Europa the evidence from surface geological features points to an internal ocean. On Enceladus the evidence is direct observation of water vapor venting from sources close to the surface," said Dr. Peter Thomas, Cassini imaging scientist, Cornell University, Ithaca, N.Y.

In the spring of 2008, scientists will get another chance to look at Enceladus when Cassini flies within 350 kilometers (approximately 220 miles), but much work remains after Cassini's four-year prime mission is over.

"There's no question that, along with the moon Titan, Enceladus should be a very high priority for us. Saturn has given us two exciting worlds to explore," said Dr. Jonathan Lunine, Cassini interdisciplinary scientist, University of Arizona, Tucson, Ariz.

--------------------------------------------------------------------------

By the way, we were discussing this story in our weekly staff meeting, and Lou Friedman kept prounouncing the moon's name "EN - sell - AH - dus" instead of the way I've usually pronounced it, "en-SELL-ah-dus." Lou's pronunciation sounds an awful lot like the word "Enchilada," and now we're all talking about the discovery of water on enchiladas...

(For those of you not familiar with tex-mex food, an enchilada is a tortilla wrapped around some yummy filling and drowned in a sauce.)

--Emily

[volcanopele]

By my watch, it is after 2pm EST. WOOHOO!!

Images associated with the ISS and CIRS papers are now up on the Photojournal: http://photojournal.jpl.nasa.gov/new

Enceladus "Cold Geyser" Model
http://photojournal.jpl.nasa.gov/catalog/PIA07799
Graphical Explanation of our model. Basically because of the appearance of the plumes, the amount of water particles entrained in the plumes, and the lack of ammonia, all point to plumes generated by near-surface reservoirs of liquid water.

Why all the life hubub? We now have a place in the solar system, besides the earth, where organics, liquid water, and an energy source have been found in close proximity to one another. Wait close proximity is not the right word, in the same spot, that's better.

BTW, the Science cover has the Rev11 mosaic

[alan]

Report: NASA Will Not Announce Life Find

NASA will not be making a "huge" announcement regarding evidence of life somewhere else in our solar system Thursday, as reported on a local news Web site and repeated by some broadcasters, according to Local 6 News partner Florida Today.
The space agency is releasing a study Thursday at 2 p.m., that is being misinterpreted by some people, according to an Internet posting by Florida Today's John Kelly.
A story posted earlier on a Web site of a local cable news outlet in Central Florida said, "NASA is planning to make a huge announcement today, about possible life in our own solar system." It is simply incorrect, Kelly said.

Oops

[scalbers]

Looks like NASA TV will have this momentarily

[volcanopele]

thanks for the heads up

[scalbers]

Hi again,

As you may have seen, NASA TV had a 2:38 long clip with excerpts from an interview with Torrence Johnson (replayed from JPL). Good to see his perspective on this.

[Guest_RGClark_*]

The media at large has picked this up, it is an announcement of subsurface liquid H2O at Enceladus, which seems to be a "no news" consequence of the jets imaged months ago. It's something if a place as profoundly obscure as Enceladus could become part of the vocabulary of the New Yorker set, if not a household name.

I don't, again, see this as news anymore, but it's a time to reflect that the Saturn system has definitely KOed the Galileans in terms of interest. Enceladus alone is almost a combination of Ganymede (old crust and new), Europa (subsurface ocean), and Io (volcanic plumes) in one. Then there's Titan. Wow.

Enceladus is still in the running for a high-priority flagship mission, although I don't know if it has the potential to climb to the top of that list among outer satellites.

It's very exciting to those of us whose primary interest in planetary science is in connection with astrobiology.
Apparently, it is also exciting to Cassini scientist Carolyn Porco:

Cassini Finds Signs of Liquid Water on Saturn's Moon
By Tariq Malik
posted: 09 March 2006
12:57 pm ET
"Saturn’s moon Enceladus may have pockets of liquid water lurking beneath its surface, feeding great jets that spew from the satellite and hinting at the possibility of a habitable environment, researchers said Thursday."
...
“This finding has substantially broadened the range of environments in the solar system that might support living organisms, and it doesn't get any more significant than that,” said Carolyn Porco, Cassini imaging team leader at the Space Science Institute in Boulder, Colorado, in an e-mail interview. “I'd say we've just hit the ball right out of the park.”
http://www.space.com/scienceastronomy/0603...sini_water.html

Also there is the question of explaining the source of this heating. One proposal is that it is due to radiogenic heating. If so that also raises the possibility that such heating could have operated on comets early in the solar systems history thereby creating environments conducive to life within comets.
If true, it would also raise the possibility such heating continues in the very largest comets and Kuiper belt objects.



Bob Clark

[ljk4-1]

Is there any way to check the water spewing from Enceladus for organic signatures,
either via Cassini or from Earth?

[JRehling]

It's very exciting to those of us whose primary interest in planetary science is in connection with astrobiology.
Apparently, it is also exciting to Cassini scientist Carolyn Porco:

I agree it's exciting -- but the headline was in November. Three models all of which included reservoirs of subsurface water were put forth then. The progression from then to now still hasn't eliminated the "may". I see this is a wonderfully important news story that happened four and a half months ago. The recent update is important, but nuanced.

[helvick]

I see this is a wonderfully important news story that happened four and a half months ago. The recent update is important, but nuanced.

This is all true but the current update is much more solidly reviewed too - and even if that isn't news for the masses it is important.

And one final bonus of all this uber PR is that its name is going to cause news teams across the globe to come up with a wonderful array of variations on its pronounciation.

[volcanopele]

I agree it's exciting -- but the headline was in November. Three models all of which included reservoirs of subsurface water were put forth then. The progression from then to now still hasn't eliminated the "may". I see this is a wonderfully important news story that happened four and a half months ago. The recent update is important, but nuanced.

There were distinct differences between the models. one suggested that the plumes were generated by warmed ice heated by a subsurface reservoir from below. The particle densities in the plume doesn't support this. Another model suggest that the sub-surface reservoir was chilled by ammonia, allowing for lower melting points. The lack of ammonia in the INMS data does not support this model either. The model we are left with is a plume generated from near-surface liquid water.

Yes, the plumes news is a few months old, but the implications of the model for the plumes is the news we are reporting.

[paxdan]

I would be curious to hear discussion as to what we have and haven't managed to rule out as a source for the energy driving the jets on Enceladus.

Tidal, radiogenic, other*?

*Could the energy be caused by cycling of material from the moon to the E-ring and back, i.e., is the moon constantly turing itself inside-out? I would be keen to hear estimates for the ammount of material being ejected from the moon versus that deposited from the ring. It is a steady state system, or would the moon have experienced significant mass wastage since its formation?

i guess these are mysteries for the extended mission

[Guest_paulanderson_*]

Good write-up on CICLOPS (Captain's Log):

http://ciclops.org

"Our detailed analyses of these images have led us to a remarkable conclusion, documented in a paper to be published in the journal SCIENCE tomorrow, that the jets are erupting from pockets of liquid water, possibly as close to the surface as ten meters ... a surprising circumstance for a body so small and cold. Other Cassini instruments have found that the fractures on the surface and the plume itself contain simple organic materials, and that there is more heat on average emerging from the south polar terrain, per square meter, than from the Earth.

Gathering all the evidence and steeling ourselves for the `shockwave spread 'round the world', we find ourselves staring at the distinct possibility that we may have on Enceladus subterranean environments capable of supporting life. We may have just stumbled upon the Holy Grail of modern day planetary exploration. It doesn't get any more exciting than this.

A great deal more analysis and further exploration with Cassini must ensue before this implication becomes anything more than a suggestion. But at the moment, the prospects are staggering. Enceladus may have just taken center stage as the body in our solar system, outside the Earth, having the most easily accessible bodies of organic-rich water and, hence, significant biological potential."

[The Messenger]

I would be curious to hear discussion as to what we have and haven't managed to rule out as a source for the energy driving the jets on Enceladus.

Tidal, radiogenic, other*?

*Could the energy be caused by cycling of material from the moon to the E-ring and back, i.e., is the moon constantly turing itself inside-out? I would be keen to hear estimates for the ammount of material being ejected from the moon versus that deposited from the ring. It is a steady state system, or would the moon have experienced significant mass wastage since its formation?

i guess these are mysteries for the extended mission

At the moment, a black oblisk seems as likely of a candidate as any. It is nice for a change, to see a puzzling source of radiant energy, and not have astrophysicists insisting that it is one of nine completely different physical environments that prove the existence of black holes.

[Guest_AlexBlackwell_*]

...about the publication of the March 10, 2006, issue of Science, which is a special issue (Cassini at Enceladus).

For those with online access to Science, the papers are now downloadable.

[elakdawalla]

For those with online access to Science, the papers are now downloadable.

I just called them an hour ago and they said they wouldn't be posted until tomorrow! Thanks for the heads up.

--Emily

[Guest_AlexBlackwell_*]

I just called them an hour ago and they said they wouldn't be posted until tomorrow! Thanks for the heads up.

Hey, what's a "Reference Librarian" for?

Typcially, the online PDFs for Science become available between 4 p.m. and 5 p.m. EST/EDT the day before the issue's date.

[Guest_BruceMoomaw_*]

Given all the effort I've put lately into flattering and buttering up Alex, I don't suppose he could make some of the "Science" papers available to us?

Till then, all I can say is what was told by John Baross and by Waite's team at the Europa meeting. Cassini's INMS was designed to analyze the much denser gases existing in Titan's extended exosphere, and so it could only analyze the gases in Enceladus' plume with an accuracy of a few percent. (An INMS designed specifically to analyze more rarified gases -- such as the one proposed for Europa Orbiter to analyze gases sputtered off Europa's surface -- could have done a much better job.) What they actually got, though, was interesting enough: 91% H2O, 4% N2 (identified as not being CO by the UV spectrometer), 3.2% CO2, 1.6% CH4, and no detectable trace of NH3. This has all been reported before in the new EGU abstracts ( http://www.cosis.net/abstracts/EGU06/09655/EGU06-J-09655.pdf ) -- but there were intriguing contradictory reports that Cassini has also found a trace of acetylene in the plume. Baross said this flatly, but the speaker standing in for Waite said that it's still highly uncertain. Even more interesting, the written version of Waite's abstract also said that Cassini detected a trace of propane -- but the actual conference speaker flatly denied this.

This thread will probably be a good place for me to put in my promised but delayed note on the Great Ammonia Mystery (why does Titan seem to have it while Enceladus doesn't?) -- which I'll do today, as soon as I get some other things in order. There have certainly been enough relevant LPSC and EGU abstracts on the subject.

[volcanopele]

I'm done talking to reporters today...

though email is still okay, Emily.

[elakdawalla]

I'm getting a brief note posted based on a chat with John Spencer; thought you all would enjoy the full text of what he told me.

We've refined our numbers a bit, we've gone through our highest resolution data and we've found a few areas of somewhat higher temperatures than we'd seen then. In July we were talking 125 K, now the highest we've actually seen in our entire data set is 145 Kelvin.

We're looking at black body radiation, so the wavelength distribution of the emission tells you the temperature. The warmer it is, the shorter the wavelength of the emission. And because we're looking at solid surfaces and most of those behave like pretty respectable black bodies, just by looking at the shape of the thermal emission as a function of wavelength you can get the temperature pretty well.

In this case, the job is simpler because the background is way colder. Even though, for instance, 145 Kelvin we have one spectrum that covers an area 6 by 6 kilometers. And we have just a few percent of that area that's 145 Kelvin, and the rest of it is at 70 or something much colder. But the heat radiation we see is completely dominated by that little bit of hot stuff.

The liquid water is all coming from the imaging team and their analysis of the plume. I guess they're figuring that the density of the particles they're seeing in these plume images is just too great to be explicable by water gas entraining particles, but I haven't looked at those calculations. Even they are saying this is an inference, not a direct detection.

When we fly past again in 2008, we'd like to look down the throat of these cracks and see 273-Kelvin temperatures down there, and we'll certainly try that.

Its approach is over the north pole, and it departs over the south pole. It's convenient for CIRS and it's inconvenient for most people, the problem being that right after the flyby Enceladus goes in to Saturn's shadow. So by the time the spacecraft is turned around to look back at the south pole, we won't be able to see the south pole in sunlight, so there won't be much in the way of images. We're perfectly happy; it eliminates all of the competition! We'll be getting good stuff. And I think that VIMS, if there's really stuff at 270 Kelvin, it should be warm enough for them to see emission at shorter wavelengths as well. Certainly at 5 microns, probably around 3 microns.

People have always invoked ammonia slurries as a way of lowering the melting point way down to about 175 Kelvin and allowing melting and geologic activity and volcanism on these cold objects. And this has been a tidy theory until we got the Enceladus data and seen NO sign of ammonia. Last time I checked, the mass spectrometer people had no sign of ammonia. It doesn't mean there's none there, but it's not got much -- there's more carbon dioxide than there is ammonia, for instance. We're just not seeing ammonia anywhere. If there is ammonia inside Pluto, and there probably is because there's nitrogen and ammonia is probably where the nitrogen came from, then there could be enough internal heat on Pluto, which has no tidal heat, but there could be enough radioactive heat that you might get some activity. The fact that Triton, which also has no internal heat source, also has this very exotic surface, clearly has signs of very recent geologic activity, implies that you can do stuff with just radioactive heat that far out in the solar system for a reasonably large object like Triton or Pluto. The thing about Enceladus is that it's so tiny that the radiogenic heat, it's very unlikely that it could do much of anything, and tidal heating is the only plausible heat source.

It's a matter of getting the internal structure right and then explaining why Mimas, which should have a lot more tidal heating, has absolutely none. It's closer in, and its orbit is way more eccentric. Probably part of the explanation is that it has to be warm in order to stay warm. We need to have a fairly soft squishy dissipative interior in order to generate enough heat to keep it soft and squishy and dissipative. If you were to freeze Enceladus solid, take it out of orbit, freeze it, and put it back where it is, it would just be too cold to get that engine started again. At Mimas that engine never started. But why that engine started on Enceladus and not on Mimas we just don't know.

[Guest_AlexBlackwell_*]

I'm getting a brief note posted based on a chat with John Spencer...

Thanks for sharing that, Emily. It was informative, especially as I was reading the CIRS paper at the same time

[volcanopele]

For those of you in the Tucson area, look for me on channel 4 on the 10pm news.

[belleraphon1]

Ok...

here I am the old foggie......

Enceladus is fascinating in so many ways.......

I an old enough to remember a quote from a scientist at a Voyager Saturn press conference where he remarked that the rings of Saturn formed when Saturn did and thats that..... back then, in the dim years of the 80's, before we had discovered hot Jupiters that have presumably migrated across billions of miles of space to park themsleves in front of their suns, solar system bodies all formed where we see them now and the same processes are operating on them now.....

Look at Enceladus, most of it is cratered, except for a few areas, where extreme stresses have fractured
the surface and erased the craters.

Whatever processes produce the heat and stress have either ioslated themselves to just a particular
area on this moon since it's formation, or there was some recent (past few hundred million years) event that produced craters over most of its surface that were then erased in certain areas by the plumes.

Or has Enceladus only recently gotten hot enough to pop its southern cork? What recent event caused the fractures?

All these questions have significant impact on how we view the solar system and it now appears that stochastic events are more important that we dreamed....

Craig

[Guest_AlexBlackwell_*]

Cassini Images of Enceladus Suggest Geysers Erupt Liquid Water at the Moon's South Pole
By Preston Dyches, CICLOPS/Space Science Institute, Boulder
March 9, 2006

[David]

By the way, we were discussing this story in our weekly staff meeting, and Lou Friedman kept prounouncing the moon's name "EN - sell - AH - dus" instead of the way I've usually pronounced it, "en-SELL-ah-dus." Lou's pronunciation sounds an awful lot like the word "Enchilada," and now we're all talking about the discovery of water on enchiladas...

Your pronunciation is absolutely correct, and Friedman's is -- let's say -- innovative. Actually, there are only two ways in which a name like "Enceladus" can be pronounced in English (and historically, only one of them is correct) -- Friedman's pronunciation isn't either of them.

Why all the life hubub? We now have a place in the solar system, besides the earth, where organics, liquid water, and an energy source have been found in close proximity to one another. Wait close proximity is not the right word, in the same spot, that's better.

Shorter volcanopele:

"Take that, Europa, you preening publicity hog! Not looking so hot now, huh?"

[Guest_BruceMoomaw_*]

Bob Pappalardo just helpfully sent me the Porco and Spencer papers, although I haven't had a chance to read them yet.

I also notice that the summary of Waite's paper ( http://www.sciencemag.org/cgi/content/abstract/311/5766/1419 ) says that Cassini did indeed find that "Trace quantities (<1%) of acetylene and propane also appear to be present." However, I don't know what to make of the next sentence: "Ammonia is present at a level that does not exceed 0.5%." Are they saying that they actually DID find traces of NH3, albeit at less than 0.5% -- or is 0.5% just the maximum upper limit for NH3 if it exists at all?

[elakdawalla]

Are they saying that they actually DID find traces of NH3, albeit at less than 0.5% -- or is 0.5% just the maximum upper limit for NH3 if it exists at all?

I'm pretty sure it's the latter. They haven't seen any evidence for it, so that means that if it's there, it's there at a level under their detection limit.

--Emily

[The Messenger]

I'm pretty sure it's the latter. They haven't seen any evidence for it, so that means that if it's there, it's there at a level under their detection limit.

--Emily

Regardless, there is not enough ammonia to trust as an antifreeze in Phoenix. Bruce mentioned earlier that there is -apparently - evidence of ammonia on Titan, but asside from speculative papers that suggest there was ammonia on/in Titan in the distant past, I haven't seen or read anything that indicates ammonia has been indentified on Titan by Cassini. What am I missing?

[Guest_AlexBlackwell_*]

I'm pretty sure it's the latter. They haven't seen any evidence for it, so that means that if it's there, it's there at a level under their detection limit.

That's what INMS is saying. From the Waite et al. paper: "Our failure to detect ammonia..."

[Guest_RGClark_*]

Regardless, there is not enough ammonia to trust as an antifreeze in Phoenix. Bruce mentioned earlier that there is -apparently - evidence of ammonia on Titan, but asside from speculative papers that suggest there was ammonia on/in Titan in the distant past, I haven't seen or read anything that indicates ammonia has been indentified on Titan by Cassini. What am I missing?

That's what I saw as well Messenger, in regards to possible ammonia on Titan:

Titan's Atmosphere Comes from Ammonia, Huygens Data Say
By Lori Stiles
February 18, 2005
http://uanews.org/cgi-bin/WebObjects/UANew...ArticleID=10597

The article says ammonia mixed with water was inferred for the subsurface of Titan.


- Bob Clark

[Anne Verbiscer]

I wouldn't be too quick to dismiss ammonia on the surface of Enceladus just yet. Models of Earth-based spectral observations support the inclusion of modest amounts (as much as 20%) of ammonia hydrate (1% NH3 H2O) in an intimate (salt and pepper type) mixture and 15% and 10% ammonia hydrate in areal (checkerboard) mixtures on the leading and traiiling hemispheres, respectively.

[volcanopele]

Wow, it's been a crazy couple of days. First, I never expected this much coverage for our special issue. I expect the usual AP and Reuters article that basically was a rewrite of the press release. Things like that. But for it to get coverage on the evening news, the front page of the NY Times, I didn't expect those. I ended up being interviewed by a couple of reporters from the two local papers (I'm on the top of the front page of the Tucson Citizen, even). I also was on the 10 o'clock news on one of the local TV stations, and my advisor was in the same report along with one from another TV station. I think he was even more surprised, given that his camera is about to go into orbit around Mars. So, I'm kinda glad this is starting to die down.

[Guest_AlexBlackwell_*]

Wow, it's been a crazy couple of days. First, I never expected this much coverage for our special issue. I expect the usual AP and Reuters article that basically was a rewrite of the press release. Things like that. But for it to get coverage on the evening news, the front page of the NY Times, I didn't expect those.

Well, all of the buzz about "NASA...planning to make a huge announcement...about possible life in our own solar system" probably helped "warm up the crowd" a little, so to speak.

[volcanopele]

I wouldn't be too quick to dismiss ammonia on the surface of Enceladus just yet. Models of Earth-based spectral observations support the inclusion of modest amounts (as much as 20%) of ammonia hydrate (1% NH3 H2O) in an intimate (salt and pepper type) mixture and 15% and 10% ammonia hydrate in areal (checkerboard) mixtures on the leading and traiiling hemispheres, respectively.

Wonder how your spectra reconcile with the lack of ammonia (or at least less than 1%) found in the plume by INMS?

I read your paper about a month on the Icarus website. I'll give it another read.

BTW, welcome to the forum!

[Guest_AlexBlackwell_*]

I wouldn't be too quick to dismiss ammonia on the surface of Enceladus just yet. Models of Earth-based spectral observations support the inclusion of modest amounts (as much as 20%) of ammonia hydrate (1% NH3 H2O) in an intimate (salt and pepper type) mixture and 15% and 10% ammonia hydrate in areal (checkerboard) mixtures on the leading and traiiling hemispheres, respectively.

I note that your paper in press with Icarus states that the CorMASS "spectral data do not contain an unambiguous detection of ammonia hydrate on Enceladus," only that your "spectral models do not preclude the presence of a modest amount of 1% NH3H2O on both hemispheres."

Like Jason, I'm interested in how the INMS data might affect your conclusions.

[Guest_AlexBlackwell_*]

That's what INMS is saying. From the Waite et al. paper: "Our failure to detect ammonia..."

For those who haven't read the paper, and to reiterate what Emily was saying about the INMS detection limits vis-à-vis ammonia, here are a couple of more clarifying passages from Waite et al.:

"Other species that could be present at a level <0.5% include NH3 and HCN."

"Statistically meaningful residuals in the mass ranges 14 to 17 and 26 to 27 daltons suggest that there may also be trace quantities (<1%) of ammonia, acetylene, hydrogen cyanide, and propane."

This might plausibly be reconcilable with the CorMASS data (Verbiscer et al.).

[Anne Verbiscer]

Wonder how your spectra reconcile with the lack of ammonia (or at least less than 1%) found in the plume by INMS?

I read your paper about a month on the Icarus website. I'll give it another read.

BTW, welcome to the forum!

First of all, our spectra measured the surface of Enceladus, not the plume, as measured by INMS. (Or were you
asking how the spectra of the surface can be reconciled with the composition of the plume as measured by INMS?)
Second, INMS is measuring pure ammonia rather than ammonia hydrate. The amount (by weight) of pure ammonia in
the hydrate used in our spectral models is only 1%, so the two measurements may be more similar than they appear.

Still, particles in the plumes and the surface particles may differ in ways other than (or in addition to) composition.
If the plumes are indeed the source of E-ring particles, then they may not coat much of the surface of Enceladus since
the spectrum of the E-ring does not match that of Enceladus. (If I recall correctly, Joe Knapp already showed how
much of the surface gets coated by plume particles in this forum some time ago.)
Also in the paper, we compare our spectra to those of E-ring particles and find that the crystallinity of water ice on the
surface of Enceladus is remarkably distinct from that of the E-ring which is comprised primarily of amorphous water ice.
Amorphous ice can be produced by flash freezing of water, as occurs in the plumes.

Thanks for the welcome, BTW. I've been lurking for a while... And I enjoyed reading your article on UMSF in the
current LPI Bulletin.

[djellison]

I enjoyed reading your article on UMSF in the
current LPI Bulletin.

Oo - I had no idea you had written that Jason - nice words

Doug

[Guest_AlexBlackwell_*]

Oo - I had no idea you had written that Jason - nice words

And for those who aren't familiar with the publication, the reference is to the current issue of the Lunar and Planetary Information Bulletin (February 2006 Issue 105). See page 10.

Well, all of the buzz about "NASA...planning to make a huge announcement...about possible life in our own solar system" probably helped "warm up the crowd" a little, so to speak.

Even Slate.com is reporting on it.

[Guest_AlexBlackwell_*]

PIA07800 looks to be another iconic Cassini image. Has anyone seen (or made) a good 1024 x 768 wallpaper for this image? I've tried; however, I've had mixed results, especially given the image's dimensions. I also have my taskbar on the bottom of my desktop, which doesn't help, either.

[jmknapp]

Still, particles in the plumes and the surface particles may differ in ways other than (or in addition to) composition. If the plumes are indeed the source of E-ring particles, then they may not coat much of the surface of Enceladus since the spectrum of the E-ring does not match that of Enceladus. (If I recall correctly, Joe Knapp already showed how much of the surface gets coated by plume particles in this forum some time ago.)
Also in the paper, we compare our spectra to those of E-ring particles and find that the crystallinity of water ice on the
surface of Enceladus is remarkably distinct from that of the E-ring which is comprised primarily of amorphous water ice.
Amorphous ice can be produced by flash freezing of water, as occurs in the plumes.

Nice to see you in the forum! I look forward to reading the Science articles and yours about said differences & how it might relate to the distribution. Practically a whole Science issue about Enceladus and a color picture of Enceladus above the fold in today's NY TImes... what a day for the Cassini team!

[Bob Shaw]

Are the physical properties of amorphous water ice different to those of 'normal' ice? I'm thinking of the way that penetrator probes would behave.

Bob Shaw

[Guest_BruceMoomaw_*]

Nice to see you in the forum! I look forward to reading the Science articles and yours about said differences & how it might relate to the distribution. Practically a whole Science issue about Enceladus and a color picture of Enceladus above the fold in today's NY TImes... what a day for the Cassini team!

It got a big color picture above the fold on the front page of my hometown newspaper (the Sacramento Bee), too. I had one of the local fast-food clerks ask me about it.

[jmknapp]

It got a big color picture above the fold on the front page of my hometown newspaper (the Sacramento Bee), too. I had one of the local fast-food clerks ask me about it.

I saw it in a newspaper bin at Starbucks--so everyone standing in line waiting for their lattes and scanning the headlines got a glimpse of Enceladus in blue.

Here's a couple quotes from the introductory Science paper by Jeffrey S. Kargel ("Enceladus: Cosmic Gymnast, Volatile Miniworld"):

"Enceladus' plume and those of Yellowstone are powered largely by gaseous carbon dioxide."

Pop the bubbly!

"The water-dominated gas composition of Enceladus' plume is consistent with low-pressure boiling of an erupted aqueous liquid that had become gas-saturated at depth (at least tens of bars pressure) with a mixture of clathrate-forming gases. Perhaps the source is a deep, gas-saturated ocean or a deep crustal pocket of water in equilibrium with CO2-dominated, CH4-N2–bearing clathrates residing on the seafloor above the rock core."

[dvandorn]

So.... Enceladus may well have a subsurface ocean of carbonated water? Opens up a whole universe of marketing, doesn't it...?

Then again, with that small admixture of CH4, it might be difficult to market pure, unfiltered Enceladian fizzy water -- at least to people who don't live next to overflowing cesspools.

-the other Doug

[Bob Shaw]

So.... Enceladus may well have a subsurface ocean of carbonated water? Opens up a whole universe of marketing, doesn't it...?

Then again, with that small admixture of CH4, it might be difficult to market pure, unfiltered Enceladian fizzy water -- at least to people who don't live next to overflowing cesspools.

-the other Doug

oDoug:

You have such a way with words, able to bring the romance of astronomy to an unwary world!

Thanks for that picture, that dream, that noble vision of... ...sewage!

Bob Shaw

[jmknapp]

But methane is odorless so it shouldn't detract from the marketability of Enceladian Springs fizzy water.

[helvick]

PIA07800 looks to be another iconic Cassini image. Has anyone seen (or made) a good 1024 x 768 wallpaper for this image? I've tried; however, I've had mixed results, especially given the image's dimensions. I also have my taskbar on the bottom of my desktop, which doesn't help, either.

I've just been playing with this as a 1400x1050 image for my desktop. It looks pretty good (to me) when resized from the original 6572x8293 down to 832x1050 and then pasted onto a flat black canvas. I didn't have any proper imaging tools on this machine that could handle the original but Paint.Net was just about able to cope although it needed more than a gig of memory to initially load it. Resizing that down to 1024x768 is noticable but it still looks pretty good to me.
The clipped south polar region is a bit of a bummer though minor flaw really. :-) (On rereading this I was struck by the fact that I had some cheek being critical of this particularly lovely mosaic.)

[ugordan]

If you're gonna decimate a huge mosaic like that to a wallpaper-sized image, you might be better off using a lower resolution image in the first place. For example PIA06249 has a similar viewing geometry as the huge mosaic, practically already fits in a screen height and has the added advantage of no mosaicking seams visible as in the large mosaic, particularly around the terminator.

[Guest_AlexBlackwell_*]

I've just been playing with this as a 1400x1050 image for my desktop. It looks pretty good (to me) when resized from the original 6572x8293 down to 832x1050 and then pasted onto a flat black canvas. I didn't have any proper imaging tools on this machine that could handle the original but Paint.Net was just about able to cope although it needed more than a gig of memory to initially load it. Resizing that down to 1024x768 is noticable but it still looks pretty good to me.
The clipped south polar region is a bit of a bummer though minor flaw really. :-) (On rereading this I was struck by the fact that I had some cheek being critical of this particularly lovely mosaic.)

Thanks, helvick. I tried it out and the image works really nice as a wallpaper. I know it's a coincidence, but the way you sized it allows Enceladus to fit perfectly with my desktop icons and taskbar position.

[Guest_AlexBlackwell_*]

I'm not sure how many people read Caltech's periodical Engineering & Science, but the most recent issue, Volume LXIX Number 1 2006, has an interesting Enceladus-related article by Douglas L. Smith entitled "A Nice Place to Visit?" (~401 Kb PDF).