Ground based observations during Huygens descent :
http://www.spaceflightnow.com/cassini/060729huygens.html

http://www.esa.int/SPECIALS/Cassini-Huygen...8TYIZBQE_0.html

Huygens Scientific Archive data set released


Yea!




That's disappointing...

Is there any news about when the rest of the Huygens data will make its way into the PDS/PSA? In August, the ESA was saying "to be released in the September-October timeframe" and the PDS has placeholders saying October, all of which have passed without any update as to the new timeline.

Some curious points from Dr. Lebreton:

"Dropping long-lived probes on the surface would also be exciting (composition of surface material and seismic-like activity which would require probe survival for 1 or 2 Titan days."

...And a cool approach on Europa also...

Hubert Curien Memorial Station

In the March 17 OPAG update from Fran Bagenal was this nugget:



--Emily

"In addition, all Huygens instrument datasets will be online by April 5 and a supporting Descent Trajectory Profile will be released in April."

Finally...maybe...April of what year

All... many papers soon to be released from "Planetary and Space Science" on HUYGENS ... instead of my inserting a huge link just go to http://www.sciencedirect.com/science and type in Titan.... Available online 27 April 2007

Craig

At 30 dollars each? :-(

Don

Don... are you able to view the abstracts?

Craig

Yes. I can access the free tidbits offered.

Don

How much of the $30 per article will those that did the actual work (the authors) see?

Right about zero.
As far as I know, only some review journals provide author compensation in the form of $ per written article page.
Before publication, copyright transfer forms are being signed, and after that everything belongs to the publisher :-)

I will paraphrase some of the articles cool-o results that were not in the abstract. (Dear Admin: If this is not cool, please yank this post).

The Raulin, Gasezeau and Lebreton article gives a quick intro to the other articles in the issue.

The two Soderblom articles provided a new look at the Huygens landing site. The free abstracts for both do a great summation.

RADAR and visible (VIMS) imagery don't match up for surface features. RADAR SAR data gives a much better clue as to what the surface looks like. The bright material may be dusted on and RADAR invisible. The VIMS data (visible pictures) can be misleading especially in the Equatorial sand seas area.

(My comment: "Near the Huygens landing area, ignore the bright material in the sand sea area visible images, it is surface paint. The RADAR data tells the real deal.")

The big exception is with the dunes. They correlate well with cat-scratch features in RADAR and with dark brown units in VIMS. ("They also always seem to be on the eastern end of the basins - probably dead end areas for wind deposition" - my comment).

The dark blue unit is always at the margins between bright continent material and the sand seas. This seems to be water ice. Huygens landed in this area.

The bright material is postulated to be a coating that is etched off by methane rain and washed (converted?) to darker materials. Bright highlands erodes/washes or is percolated through by methane rain to dark streambeds washed into dark blue (ice) basins. ("The dark blue basins are presumably covered by the mobile dark brown sand dunes at the eastern ends and are left exposes on the western ends" - my comment).

The geomorphology of the Hugens landing site was also discussed. Two 3D images were shown: one for the highland area, and one for one of the light colored ridges in the dark blue flat area (which we now now is mostly dirty water ice).

The highland area to the N of the Huygens landing site is steep (angle of repose) and deeply etched by streams. The steam pattern show evidence of faulting. The topography of the higland is about 200 m above the dark blue dirty ice flat level. A image was shown with a stream basin divide as well. The dark streams show where the bright coating has been washed/eroded/modified away.

A very nice image was shown that everlays faults (for highlands) and interpreted stream flows (for dark blue dirty ice flats) on the Huygens landing site image.

The dark blue flat area has several bright ridges showing. From the topographic reconstruction of this area (I call these features the "spooky hooded dude" terrain), the ridges are 100 m high (whoa!). These ridges may be ice sand or ice gravel bars left behind by a massive flood (100 m high gravel bars!). All the features at the margin of the dark blue dirty ice flat level show evidence of a massive flow from west to east. This includes the shoreline of the bright highland area to the north (like that Long Island shaped feature). The source for this massive flow is to the west. There is a second set of streams that cuts across the big bars from the NW to SE this may be from a lower flow volume - normal flood rain events.

The spooky hooded dude terrain was emplaced during a massive flood or floods that ripped down the big channel (from the WSW). The flood rains from the highlands did not cause the massive flows that made the spooky hooded dude terrain.

-Mike

Thanks, Mike

Just to try and wrap up this off-topic discussion, here, I'd like to point out that this scientific publishing system is in danger of failing. You see, the vast majority of all of these scientific journals have as their primary circulation university libraries. Most actual scientists can't afford to order these journals for themselves, but most actual scientists work directly for universities.

In America, at least, university funding is hitting all-time lows. Universities are cutting back on "frills," and subscriptions to every minor Elsevier publication are more and more being thought of as "frills."

Unless trends reverse direction soon, Elsevier and the other science publishing houses will find that their subscription income has dropped to almost nothing, and with that, advertising revenue will also dry up. These journals will go out of print.

Either the whole "publish or perish" process will need to be changed, or the publishing process itself will have to change. For myself, I'm beginning to think it's something that governments might have to take on...

-the other Doug

Well - slowly - some people at least 'get it'
http://www.marsjournal.org/

All free, in full....beautifully done.

Doug

My thanks too Mike. I love the bit about the massive eastward flood and the giant gravel bars. As soon as I saw those bright ovals and arrowhead shapes (hooded dudes) in the foreground of the first Huygens mosaic my first thought was 'That stuff FLOWED into place to form those shapes'. I've been trying to hang onto that first impression even as the revealed height of the topography seemed to make it less and less plausible. Now I'm delighted to find that the sense of implausibility was just down to my rather pathetic failure to conceive of a big enough flood! I should have known - with an atmosphere that can hold and then drop 10 metres of methane . . .

My main query with this picture concerns the large-scale levelness of the 'dark blue' plains surfaces, and their identification as dirty water ice. I have to believe the spectra to some extent, but the problem is that the only ways I can see to form such level plains are: 1. solidified liquid flow, or 2. sedimentation that has filled and covered underlying topography. Now, is it being suggested that we have here a genuine water-ice 'lava' plain analogous to flood basalts on the Moon or Mars? Or are we saying that dirty stuff (including some water ice dust) flowed repeatedly off the highlands with the rains and was deposited as 'dark blue' sediment? That is two very different scenarios, but either way the gravel-bank-forming events are distinctly more recent. At the Huygens site we seem to see small changes in the level of the 'dark blue' surface either side of certain gravel banks. That's why I favoured movement of the dark stuff during the same events that emplaced the banks. I may have to abandon that idea but I haven't quite done so yet. (If I'm right there should be buried gravel banks interleaved with the dark blue unit, but I don't know how to test that.)

From the figure in the article (Figure 7 in the article), the lowest part of the enclosed area in the gravel bar (one of the holes in the "spooky hooded dude") is at 20-40 m in elevation above the lowest part of the more open dark channel located to the SE of the central low point of the enclosed area.

Looking at the DISR image and taking the center as the Huygens landing site, the "peak" of the spooky hooded dude is to the ENE. The topographically determined oval was at ESE. Further out along the same vector from the Hugens landing site, the dark channel flows SW to NE. This channel seems deeper.

But the error bars for this topographic determination may be as much as 30-50 m.

With this caveat, it appears that the oval inside the emplaced gravel bar is slightly higher, but not as high as the emplaced gravel bar.

One possibility is that the dark material is composed of small grains of dirty water ice that acts and flows like a slurry. Embedded ice cobbles would get sorted, tumbled, and might make it to the boundaries of the slurry. The density of the slurry and the density of the ice cobbles should be real similar (I'll take 1 g/cm3 for the water and 0.8 g/cm3 for the methane-ice gravel mixture).

Once the material starts to slow down and "set up", the ice cobbles get emplaced, but the more liquidy methane and dirty ice fines melange oozes away. This would leave the gravel bars high and dry, but the lower dirty ice as flatter plains.

This might be a fun thing to try to model in the lab.

Future altimetry studies of the Equatorial Sand would be really helpful. Could we see the differences where the flood slurries stopped? Or is the area between the highlands a sort of huge alluvial fan?

[When I first saw the hooded spooky dude feature, my first thought was "glacier". Maybe a methane-water-ice slurry would end up leaving moraine-like features at it's terminus?]

So did the massive methane floods evaporate away from the basin?
Or percolate down beneath the dirty ice dark blue sands? (different from the wind blown dark brown dune sands)

-Mike

I'd bet that there are buried gravel banks from past floods. How could we spot them?

Could RADAR signatures help? Could a RADAR signature from similar cobble structures buried under a few meters of ice sands be distinguished from structures above the surface?

Too bad Huygens didn't have ground-penetrating RADAR on it's descent package!

-Mike

Thanks Mike for the paraphrasing....

Found these bit from the "DISR Imaging and the Geometry of the Descent
of the Huygens Probe within Titan’s Atmosphere" paper interesting:

["Huygens moved on average in the direction of 2° north of east from 145 to 50 km altitude,
turning to 5° south of east between 30 and 20 km altitude, before turning back to east. At 6.5 km
altitude, it reversed to WNW, before reversing back to SE at 0.7 km altitude.

At first, Huygens was tilting slowly by up to 15° as expected for a descent through layers
of changing wind speeds. As the winds calmed, tilts decreased. Tilts were approximately
retrieved throughout the main-parachute phase, but only for 160 specific times afterwards.
Average swing rates were 5°/s at high and low altitudes, but 13°/s between 110 and 30 km
altitude. Maximum swing rates were often above 40°/s, far above the design limit of 6°/s, but
they caused problems only for a single component of DISR, the Sun Sensor. The excitation of
such high swing rates on the stabilizer parachute is not fully understood.

Before the parachute exchange, the rotational rate of Huygens smoothly approached the
expected equilibrium value of 3 rotations per vertical kilometer, although clockwise instead of
counterclockwise. Starting at 40 s after the parachute exchange until landing, Huygens rotated
erratically. Long-term averages of the rotational rate varied between 2.0 and 4.5 rotations/km.
On time scales shorter than a minute, some 100 strong rotational accelerations or decelerations
created azimuthal irregularities of up to 180°, which caused DISR to take most exposures at
random azimuths instead of pre-selected azimuths."]

And the desription of the surface is captivating to me.

[Within seconds after landing, the parachute moved into the field of view of one of the
spectrometers. The observed light curve indicated a motion of the parachute of 0.3 m/s toward
the SSE. DISR images indicated that the probe did not penetrate into the surface, assuming a
level ground. This impact of Huygens must have occurred on major rocks or some elevated area.
The unexpected raised height increases ice-rock sizes by 40 percent with respect to estimations
made in 2005 (Tomasko et al. 2005, Nature 438, 765-778). During the 70-minute surface phase,
the tilt of Huygens was 3°, changing by a small fraction of a degree. The apparent horizon
looking south to SSW from the landing site was 1-2° above the theoretical horizon, sloping by 1°
up to the left (east). Our best guess puts the horizon as a 1-2 m high hill in 30-50 m distance.
We detected the refraction from warm, rising air bubbles above our illuminated spot. Bright,
elongated, cm-sized objects appear occasionally on the surface. If real, they could be rain drop
splashes or fluffy particles blown across Titan’s surface.

To paraphrase the article regarding the remark on bold, there are 6 six out of the 80 surface images that show bright features at random locations. If they are near the surface they are about 2cm in size. They comment that a more detailed study is warranted.

Craig

This is more or less what I suggested here (post 69):
http://www.unmannedspaceflight.com/index.p...4003&st=60#

However I'm not sure why, if both the pebbles and the 'sand' are made of water ice, one is light and the other dark. Wouldn't they just grade into one another? They look very distinct and different in the Huygens surface view.

I have no really good idea, either.

Maybe the cobbles are freshly eroded from the highlands and transported only a fairly short distance. While in contrast, the ice sand grains have had time to roll around and get all coated with organic yukkies in the Equatorial Sand Seas.

(This is analogous to Earth, sands tend to get transported around while the rocks boulders in a shingle beach are more local.)

-Mike

I think much caution - and patience - is required here. Even the experts from different instrument teams are interpreting things differently (like the blind men and the elephant). One of the latest papers asserts that there is light as well as dark organic dust, or light dust that get's darkened by some process once on the surface. Possibly we have both light and dark ices too. Are these pebbles even of the same material as the bulk of the light highlands? Is either necessarily water ice? It's all too much for me at this stage. All I see are various materials that appear to have behaved dynamically in a certain way (broadly as we have both described and as the paper you paraphrased confirms) that definitely includes liquid flow.

If pushed to a guess I'd say the liquid was mainly methane rained out from a massive eruption cloud produced by a large cryovolcanic event, but of course once you postulate such an event there is also the possibility of highly mobile cryolavas. I hope a close look at Adiri will ultimately reveal the source of the outflow.

Could a massive flood cryovolcanic event also be a possibility?
(Earth analogs : Deccan traps and Columbia Plateau flood basalt events)

I agree that for the materials in the Hugens surface image alone, there are many, many possibilites. And the spectroscopic evidence hasn't completely nailed any of the items to the point where we can say that X observed material is composed of Y% this , Y%that, etc.

I would just looove to know just the composition of the dark grains in the Huygens image. Is it a homogeneous mixture, is it coated grains (my favorite), or is it heterogeneous bits of this and that stuck together?


If a second lander had plopped down, would the grain color be different, would the cobbles also be different.

(Should always send two.......)

-Mike

Open and closed cell foams - perhaps a possible answer to this:- ??

"However I'm not sure why, if both the pebbles and the 'sand' are made of water ice, one is light and the other dark. "

Yesterday, 09:47 PM Post #23

See:

Voss, L. F.; Henson, B. F.; Robinson, J. M.
Methane thermodynamics in nanoporous ice: A new methane reservoir on Titan
J. Geophys. Res., Vol. 112, No. E5, E05002
10.1029/2006JE002768
04 May 2007
Abstract

posted by Alex Blackwell in 'Titan's Methane Cycle'

Here is my suggestion:
Suppose at least some of Titan's surface ices are frozen in an aerated pumice-like state. Suppose this can take on either an open-cell structure or a closed cell structure on a variety of scales, including nanoscales. The open-cell ice-foams would be more easily broken down into 'sand' and would also be good at absorbing organics, so darkening in the process. The closed cell ice-foams, on the other hand, would erode more slowly into smooth pebbles and be unable to absorb organics, thus remaining light-coloured (and buoyant).

It is real difficult, using the raw images which are not in sequence, to come up with any sense of order concerning the 'bubble's'. Has the image sequence every been put together in a time sequence?

Yes, that was one of the first things done here after the images were released. If I recall correctly, there were a number of comments at the time that there appeared to be occasional movements in the movie.

Here is the post by djellison, earlier on this thread, where Doug made the Huygens surface images into a movie that showed apparent differences between images.

Bill

I just had a protective structure idea for for early Titan explorers.
Click to view attachment
http://www.gjmurphy.com/snippets/ice/ice.asp

ah yes, you can see the 'drops' in the end of doug's sequence...i think

djellison --
"It's landed in a bloody STREAM...watch this carefully"
http://www.mars.asu.edu/~gorelick/huygens1.gif

Yes!!! I can see the shallow, clear stream flowing
over a bed of rounded river rock!

All in the imagination of course. But at one time.... or repeated times....

I tried finding a listing of the particular image numbers that show these features but could not find one.
Always thought there was something going on at the surface.

To paraphrase the paper...

All of these features appear where the ground is closer than 3 m distance; none appear in the sky.

They also note refraction effects... saying that a parcel of air with a 1 K temperature difference with respect to the surrounding air causes refraction of light some 15 times larger than for a similar parcel on Earth, since Titan’s air density is five times as large, while its temperature is three times lower. They haven't done any modeling of refraction to check if this explanation is reasonable.

Craig

Excellent! All that's missing there is the dark stuff for grouting . . .

So...if the "spooky dude" formation in the Huygens image is a big sandbar formation as described by Soderblom et al., how much flow was needed to make it?

Given a channel width of 5 km as measured by the Huygens DISR: http://www.planetary.org/explore/topics/sa...an_huygens.html


And plugging it into the empirical formula used by Jaumann et al in the LPSC 2007 abstracts (#2100)

Flow (m3/sec) = 0.46 * 1.61 * channel width (m) ^[1.22]

{Huygens stream : 250 m wide; published value = 900 m3/sec; calcd value w/formula = 736 m3/sec: I have no idea where the discrepancy is}.

Using this adapted formula, we get a flow of 28,000 m3/sec. [If we do a straight proportion we get 18,000 m3/sec, which is still pretty big]

This is almost twice the Mississippi River’s flow. http://www.unmannedspaceflight.com/index.p...ost&p=88181

It is 10% the flow of the flood released when glacial Lake Bonneville released through the Red Rock Canyon (estimated at 420,000 m3/sec).

That’s a heckuva lot of methane (slurry).

What are possible origins of such a large flow?
A: massive, massive methane rainstorm (liquid methane is the fluid)
B: Cryovolcanic flood basalt (water is the fluid) flowing downgradient
C: ground liquification of methane/ice sands to make a slurry, which flows [tectonic/impact/etc] downstream
D: ground liquification of methane/ice sands to make a slurry which causes a methane tsunami [tectonic or impact]
E: release of liquid methane during a past ice (Liquid Methane) age due to dam break (what would be the damming substance? Acetylene?)
F: massive release of methane to form a type of cryolahar. In this case there is a massive blowout of methane from the subsurface reservoir, and the methane is vaporizing away as the ice sand/liquid methane layer speeds along.
G: other stuff?

Anyone got clues?

-Mike

For comparision, Glacial Lake Bonneville ripped down the Red Rock canyon on it's way to the Snake River Basin. Just after passing Red Rock canyon it left a very large sand bar (2.2 km x 23 km, 30 m high).

This can be seen at 42 deg 40 min 55.45 seconds N and 112 deg. 13 min 03.47 seconds W. (near McCammon, ID)

From Huygens images on Titan: sand bar (spooky dude formation) size: 4 km x 10 km, 100 m high.

-Mike

I'd go for A 75 percent, B 20 percent, others 5 percent. I'm still trying to get my head round the imlpications of just how much methane the atmosphere can hold and then rain down on rare occasions.

Brrr, in at least two senses of the word. Long-lived landers/rovers are looking increasingly risky here; better start refining those blimp designs...

I get the odd impression that Titan is, in a sense, always that close to massive flooding from precipitation, and that the equatorial regions are really wannabe ocean beds...sort of what Earth would be like if the average surface temp was hovering right around 100 deg C. and the atmosphere was supersaturated with steam.

In one sense, it's like Earth but at the opposite end of the temperature range of the "dominant-most-likely-to-be-liquid-at-ambient" phase change temperature.

On Titan, the average surface temperature is just above the to it's boiling point of methane. So the dominant potential liquid (methane) is in gas phase. In extreme cold climate cycles, maybe Titan would be an ocean world, and in hot climate cycles, Titan would be a vapor world.

On Earth, the average temperature is pretty close to the freezing point of water. In extreme warm climate cycles (e.g. Jurassic), Earth would be an ocean world. In extreme climate cycles, Earth would be a frozen world (pre-Cambrian Snowball Earth)

-Mike

Another effect is that water sucks up/releases a huge amount of energy during phase transitions ("gotta break them intramolecular bonds"). [EDIT: Correction: "gotta break them intermolecular bonds"]

Hydrocarbons only have relatively weenie induced dipole (formerly VDW) interactions and so don't really stick together so well. The amount of energy involved during condensation/evaporation is small in comparison to water ('bout 6x less if I recall correctly). [In the chemistry lab, trying to rotovap off water requires continually shoveling dry ice in the condenser trap as so much energy is released during the phase change back to water]]

Fun experiment around the campfire: Fill a paper cup with water and put it on a hot rock in the fire. The water will boil and prevent the fire from burning the paper cup. The energy is absorbed by water and keeps the paper cup temperature at a non-combustible 100 C during the boil off. DON'T try the same experiment with a hydrocarbon solvent.

Safety tip around the home: After the tea kettle has boiled on an electric range, and you've turned the heat off, put the kettle back on the hot burner and it will quickly bring the hot burner down to a lower temperature (if you can stand the tea kettle singing). Trying to get the liquid water to phase change to vapor will suck the extra heat from the hot metal burner.

Hydrocarbon-driven meteorologies will have to be much bigger than water-based meteorologies to move the same amounts of energy.

For a given amount of energy, you can evaporate 6x the amount of methane than water.
And 6x more methane condensing will be required to give the same amount of energy as a unit of water.

Titan clouds will not generate as much condensation heat. [More rain/cloud]
Titan lakes will not require as much heat to evaporate. [Faster evaporation]
Massive clouds (6x?) will be needed to transport the same energies on Earth.

Titan - Land of Big Weather


-Mike

Intermolecular bonds, surely :-)

But land of big weather is right. Note that Titan doesnt have to shunt around
the same energies as Earth - maybe 1000 times less.

I think it is the combination of this weak energy flux, together with the massive
atmospheric inventory of methane, that gives Titan intense, but very sporadic,
rainstorms. The system behaves like a relaxation oscillator - charge trickles
in until a threshold is reached, then it all dumps out to start again. In this sense
Titan is an extreme of a pattern being seen on Earth as the greenhouse effect
increases - higher temperatures allow higher specific humidity before the
relative humidity threshold for rain is reached, thus more intense storms are
permitted. However, the system is being forced by the same flux as before,
so the flux in these intense events is stolen from the weaker events. result -
more massive storms separated by longer droughts.

Fascinating as usual, you guys...thank you! I look forward to observing the equinox more and more...there may be some incredibly significant things with respect to climatology in general to be learned from Titan!

Thanks for the correction! [I will edit my previous post]

(Freudian slip, we are trying to use intramolecular bonds to sneak a molecule with a polar functionality past the cell membrane to get better cell penetration.)

On Titan, I think the smallest molecule where intramolecular bonding could occur would be glycine [H3N+CH2COO-] or beta-alanine [H3N+CH2CH2COO-]. These would be in the solid phase at Titan (and Earth's) temperatures (m.p.(dec.) 513 K for Gly; m.p. 475 K for b-ala).

-Mike

I can find some weakness in this argument. On Earth, the biggest storms are self-pumping: Condensation of moisture releases energy as wind. This reduces atmospheric pressure near the surface and increases the evaporation rate.

Since methane vapor has a much lower heat capacity than water vapor, the potential for self-pumping is limited. So the question becomes: Which is most important in the creating of a massive storm: Greenhouse induced stability or self-pumping? Is the surface of Titan saturated with methane moisture, like Florida, or a methane desert like Arizona?

Actually, I think "self-pumping" is still OK for a methane storm.

Methane releases less energy when it condenses, but it also requires less energy to vaporize. So a storm should still be able to self-pump. The absolute amount of energy moved per unit of methane will be smaller than with the corresponding amount of water, however. (You couldn't kick start a terrestrial water-based hurricane with a series of methane storms).

I wonder if a little cute self-contained mini Hadley cell methane weather thermodynamic engine (i.e. methane hurricane) could exist on Titan?

If one could start, would it morph into a planet-wide event?

-Mike

I think the best way to start a big event is to release some methane at the surface. I calculate that 1 cubic metre of pure methane at the surface of Titan has, due to its buoyancy, about 100 kilojoules of potential energy.

Edit: Double that if it convects to 40 000 metres, and no, it doesn't have to be warm.

once a parcel is lifted above a certain level (about 3 km if I remember correctly) a cloud can rise to> 30 km simply by release of latent heat. There are some models for Titan's South polar storm that show this :

Barth and Rafkin
Hueso and Sanchez-Lavega

Also, this is apparently happening for the mid-latitude clouds:

Griffith et al.

I applaud you for considering things thermodynamically.
I have applied some heat engine arguments to
show that Titan's convective plumes should be sparse but are still vigorous
(the low energy flux manifests itself as rarity, rather than weakness, of
convective events)

http://www.lpl.arizona.edu/~rlorenz/titanplumes.pdf

Can somebody take the Huygens surface "movie" and give it the same sort of processing as the MER dust devil movies? It'd be much easier to see the subtle frame to frame variations (beside the compression artifact noise) in such a rendition.

The problem with that treatment is CCD noise coupled with severe compression artifacting would kill any change that's not readily apparent and would introduce ghost details where there are none. I'm wary of claims raindrop splashes have been detected in the imagery precisely due to this. There's only so much you can pull out of a limited dataset.

True - It is my understanding the images were reduced to jpgs before transmission - that leaves little room for serious enhancements. There may be some color filter variations from image to image (yes/no?), but basically we have one picture of some pebbles. Simple was clearly the buzzword when Cassini and Huygens were scoped/rescoped.

The raindrops or mud splashes - I think these are found in the smugging found in the downward pointing lens - that is clearly where the parachute makes a ghostly appearance.