Celestia Forums

Hello people,

rthorvald (as Guest) wrote:Titan surface movie clip:
I don??t know exactly what this is, if it is legitimate or not, but it *is* interesting... Have patience, it is a 5MB download:
http://www.mars.asu.edu/~gorelick/huygens1.gif
It is an animated gif from the 1st. landing photo.

I recently found this via SlashDot. I downloaded and viewed said GIF about an hour ago. The website by Anthony Leikens says this is "images of the surface of Titan and contains some strange artefacts."

Could anyone who's seen it please tell me whether they agree that the middle horizontal band on the 'ground' is in fact a running stream of liquid? Thanks.

I wanted to see what these 'strange artefacts' were, and after realising that the GIF must be a kind of time-lapse movie of the same ground scene after Huygens landed, I tried looking for them. I think he is referring to some of the stones and pebbles appearing to suddenly brighten or jiggle for a moment. I realised at 11:40CET that the entire centre-horizontal band of the ground plain looks different: it's clearer of stones than farther away, the few stones nearer seem to twitch more.

Also, there are two stones near the centre-left that have dark tails to their right, the streaming seems to be from left to right, and there are other stones below and to the right that seems to twitch and jiggle, as does the 'smooth' area containing these stones - just as if the stones are under a stream of clear 'liquid' - a refraction effect from rippling flow. I can see that the stream edge on the far side is before where all the further rocks start (note how much steadier they are compared to the emptier region just in front containing flickering stones), but I think the near stream edge comes right up to Huygens.

Since then, I looked for anyone else commenting like this on SlashDot and here, but not so far.

Anyone? I'm not looking to be proved right, just does anyone see the same effect?

Spiff.

P.s., the dog-ear in the upper-right. Does anyone agree we might have a ridge-mountain in the backgroud - not sky, and that the diagonal is the mountainside?

Spaceman Spiff wrote:Hello people,


Could anyone who's seen it please tell me whether they agree that the middle horizontal band on the 'ground' is in fact a running stream of liquid? Thanks.


Spiff.

P.s., the dog-ear in the upper-right. Does anyone agree we might have a ridge-mountain in the backgroud - not sky, and that the diagonal is the mountainside?

Spiff,

certainly a fascinating hypothesis...I magnified the 100 animated GIF's by a factor of 2 and replayed the images with varying much slower speeds.

I can certainly see your point, notably the far "river border" seems suggestive due to the marked change in density of pebble stones. I would be very curious knowing the time scales involved. Do we know what the actual time intervals were between one shot and the next one? After enlarging the GIF's, artefacts become clearer visible. Those shadow-like dark streaks, visible /always/ on the /rhs/ of the pebbles and all pointing into a similar direction are also most intriguing! These were also mentioned on the ESA figure caption (color photo), as traces of erosion probably due to /fluvial/ activity. Of course, this could have happened long ago. On the other hand, it was also mentioned by NASA/ESA that the landing site looks somehow "swampy", with traces reminiscent of an "inondation" in the /recent/ past.

Another issue: The /pattern/ flickering over the neaby pebbles is much more pronounced than within the distant
areas (sky, mountain?). If it was due to imaging artefacts, there is no reason for a stronger flickering nearby.

Darmstadt scientists stated yesterday that the foreground objects are most probably big rounded pebble stones and NOT ice (rocks)! If they are part of a flowing river environment their smooth round shape looks quite natural. Bye applying maximal contrast enhancement, it seems quite evident that the densely distributed stone field objects in the "dry" background area, are largely of very /irregular/ shape!

Bye Fridger

Spiff,

meanwhile I checked that the sun was rather high up in the sky at 13:45 CET (on Titan). I guess about 60 degrees. I have no idea what the angle of total reflection of liquid methane (CH_4) would be??? In other words: Given that we know the position of the sun (producing a rather diffuse illumination ) in the sky, the question would be whether we should have noted reflection effects on the fluvial surface or whether a totally transparent liquid methane hypothesis might well be consistent? Most probably, the sun was positioned in the 'back', which would supress strongly any visible surface effects.

(Evaporating) liquid methane seems to be the best present working hypothesis for a number of reasons: spectral analysis, surface temperature of -180 degrees Celsius and the discovered dense layer of methane in the atmosphere between 18 and 20 km altitude. As officially stated, the latter points towards huge resurces of (evaporating) methane on the surface ...

Bye Fridger

Hallo Fridger,

t00fri wrote:Another issue: The /pattern/ flickering over the neaby pebbles is much more pronounced than within the distant areas (sky, mountain?). If it was due to imaging artefacts, there is no reason for a stronger flickering nearby.

Ah, glad you noticed that too. I'm trying to think of other ways that the flickering could not be because of moving liquid. So far I have:
- JPEG artefacts. The compression and blockiness could account for the flickering. However, your above stated observation might count against this (I thought that too, so that's why I'm confident that the flickering isn't JPEG artefacts).
- Thermals. However, the sun should have been above the horizon for several days now, so there shouldn't be strong thermal imbalances (?). Also, thermals should be across the whole images, concentrated to teh horizon, not the boulderless area.
- Out of focus droplets on the camera lens/screen. A spot-like shadow can be seen 'dancing' down from the other side of the 'stream' towards Huygens (it effects the shadow of the round pebble sitting in a hollow with the white cap on top). I think it might be an out of focus droplet sliding down a screen, provoked by wind. Otherwise I don't know what that is, but the other flickering is definitely not like this moving shadow.
- Fine dust picking up in wave-like patterns over flat sand beds due to wind. The movement just doesn't seem right though.

t00fri wrote:... the question would be whether we should have noted reflection effects on the fluvial surface or ...

Actually, I don't think the flickering is due to specular reflection on rippling liquid, but rather it's the images of underliquid rocks bobbing due to refraction though the liquid.

t00fri wrote:(Evaporating) liquid methane seems to be the best present working hypothesis ...

I didn't read about that, but this morning I would have thought the liquid was ethane rather than methane because the methane is so much more volatile. Otherwise, I don't know.

Thanks for your comments, though.

Presently, I still think a flowing stream of clear liquid (ethane) is being shown.

Anyone else?

Spiff.

Here is a graphical reminder of what Spiff and I were talking about for people who have not had a chance of studying the animated GIF file in detail:



The red line marks the speculated "far" river border.

The striking difference in "pebble" density is obvious on the two sides of that border line. The rocks beyond the red border appear rather sharp-edged and irregular in shape, quite unlike the rounded soft-edged pebble stones in the foreground ("river bed").

The blue lines emphasize the dark shadow-like streaks always to the right of pebbles and pointing into the direction of the presumed liquid flow...

Bye Fridger

Very difficult to judge.
As you may see, the whole picture is wobbling as if overlayed by a thin liquid layer - just watch the horizon or the stone shapes. So maybe the fluid effect is just a sub-phenomenon of this wobbling effect.

I'm wondering if these small jumpies are some kind of frogbirds hobbling over the stones, or if there is a heavy storm blowing ice fragments through the landscape.

maxim

Spaceman Spiff wrote:- JPEG artefacts. The compression and blockiness could account for the flickering. However, your above stated observation might count against this (I thought that too, so that's why I'm confident that the flickering isn't JPEG artefacts).

JPEG artefacts in an animated GIF... I'd really like to know how much processing these images have suffered. The 8x16 grid of 32x32-pixel squares making up the image clearly indicates some kind of compression, but are you saying that JPEG was used for compression already onboard Huygens, before transmission to Earth? Maybe bandwidth constraints made it necessary, but I'd say lossy compression is better used for photographing things we already know how they look rather than alien worlds. I want the raw bits, not some automatic removal of "unnecessary" detail.

Without seeing anything float sideways, I'm not convinced the flickering is an indication of liquid in motion, although I'd certainly like Huygens to have landed next to a river! Having fulfilled its mission, it should have made a fire and spent the rest of its short life roasting marshmallows.

Spaceman Spiff wrote:- Out of focus droplets on the camera lens/screen. A spot-like shadow can be seen 'dancing' down from the other side of the 'stream' towards Huygens (it effects the shadow of the round pebble sitting in a hollow with the white cap on top). I think it might be an out of focus droplet sliding down a screen, provoked by wind. Otherwise I don't know what that is, but the other flickering is definitely not like this moving shadow.

I'm not sure whether we are looking at the same flickering, but I think I see a few blurred "snowflakes" coming down to the right. Maybe there are droplets trickling down on the lens as you say, or the "snow" is falling off the upper parts of Huygens right in front of the camera. It would really help to know the approximate frame rate here. Are there any chemicals that might form snow on Titan?

Spaceman Spiff wrote:P.s., the dog-ear in the upper-right. Does anyone agree we might have a ridge-mountain in the backgroud - not sky, and that the diagonal is the mountainside?

I don't think so; the "mountain" looks much too smooth to be real. The dog-ear in the upper right appears to correspond to the one in the lower left, except that the latter gradually disappears after a few frames (I can't guess why). There is another bright artefact in the upper left, stretching from the top of the image well "below" the horizon. I'd blame it on the camera. Has anybody seen a detailed drawing of Huygens showing the design and location of the different imagers (and other sensors)?

maxim wrote:the whole picture is wobbling as if overlayed by a thin liquid layer - just watch the horizon or the stone shapes. So maybe the fluid effect is just a sub-phenomenon of this wobbling effect.

Please excuse me for stupid questions, but does anyone know the temperature of the probe compared to the temperature on the surface? If Huygens was warmer than the material on the ground, maybe what we see is just outgassings from the ground because of it, obscuring the camera lens?

-rthorvald

That sound's reasonable. It shouldn't be too could after it's atmospheric ride.

maxim

maxim wrote:That sound's reasonable. It shouldn't be too could after it's atmospheric ride.

maxim

Huygens carries a "cosy" little Plutonium heater on board

The 72 pound Plutonium load of the Cassini-Huygens spacecraft gave rise to quite a bit of controversy...Plutonium Dioxide is the deadliest substance known by science.

The concern is that the craft could go off-course, burn up in the Earth's atmosphere, and shower the planet with the 72-pounds of plutonium which give it power.

I could not find out how much Pu-238 is on board of Huygens...in total it's 72 pounds.

Bye Fridger

Ah, so nice to get a debate going...

I stared at the 'movie' looping over and over again last night for a while, trying to see things one way or another. At the moment, I think I'll have to back off from 'stream', and settle for two puddles with slight waves moving back and forth. The only impression of 'flow' I'm left with is (refering to Fridgers marked picture above) from the two streaks immediately right of rocks, marked just below the red line marking the far bank.

Thanks, Fridger, for marking up a picture...

t00fri wrote:The blue lines emphasize the dark shadow-like streaks always to the right of pebbles and pointing into the direction of the presumed liquid flow...

Yes, the red line marks where I perceive the far side of the 'stream' is. The two blue lines correctly pick out the dark left-to-right streaks after two rocks that I note.

However, I believe the other three blue lines merely outline fuzzy shadows of rocks, and their length and direction is consistent with a sun angle to the right* and 60?° above the horizon. also, the light from the sun remains sufficiently directional after haze scattering to do this, so yes the local Titanian Potato-oid race can watch the sun cross the sky...

By the way, the ESA information is that the shoe-shaped shadowed rock just to the right of the first sharp band down in Fridger's red line is only 13 cm across and two metres away from Huygens lens. That means the 'stream' or 'puddles' might only be 1 or 2 feet across.

Now, I'll try to answer the questions people ask...

Fridger wrote:I would be very curious knowing the time scales involved. Do we know what the actual time intervals were between one shot and the next one?

andersa wrote:It would really help to know the approximate frame rate here.

I count 110 frames. I read that Huygens data was received by Cassini for 90 minutes after landing, so I conclude a frame rate of a bit faster than one per minute.

maxim wrote:Very difficult to judge.
As you may see, the whole picture is wobbling as if overlayed by a thin liquid layer - just watch the horizon or the stone shapes. So maybe the fluid effect is just a sub-phenomenon of this wobbling effect.

Yes, I see the general shimmer too, but I should clarify that what I'm specifically looking at is the difference in shimmering behaviours of two particular rocks. I can't do as Fridger and send a drawing, but if we take the top-left of these 256?—508 pixel frames as co-ord 0,0, then watch the behaviour of these rocks: they are at co-ords 215, 219 and 217, 245 (i.e., just below the first one). The top rock is flat, muted and darker than the bottom one which looks comparatively white, yet it seems to flicker so much more the white rock which it remarkably steady in all this shimering. Why? I think it's because it is just below a surface of liquid that has a slight swell blowing about in the wind, and it appears to flicker because the refraction of a liquid makes it appear to move position slightly. This behaviour in itself doesn't entail any stream, so I'm degrading my conclusion to puddles. There may still be slight flow through them though... I find two other areas where there appears to be a greater level of shimmering.

maxim wrote:I'm wondering if these small jumpies are some kind of frogbirds hobbling over the stones, or if there is a heavy storm blowing ice fragments through the landscape.

I think the "small jumpies" are what the Anthony Liekens web site originally referred to as "strange artefacts". I don't know what they are, but I think they're separate from what I'm writing about. Rain? Snow? Dust? Ice grains blowing in the wind? Creepy-crawlies? I've managed to satisfy myself that each appearance is of a different object. Play the movie too fast, and it looks like one object dancing around the area. Play it frame by frame, and you see at least one interleaving frame where there is no object before something else appears in a different place.

andersa wrote:
JPEG artefacts in an animated GIF... I'd really like to know how much processing these images have suffered. The 8x16 grid of 32x32-pixel squares making up the image clearly indicates some kind of compression, but are you saying that JPEG was used for compression already onboard Huygens, before transmission to Earth? Maybe bandwidth constraints made it necessary, but I'd say lossy compression is better used for photographing things we already know how they look rather than alien worlds. I want the raw bits, not some automatic removal of "unnecessary" detail.

Yes, I'm really disappointed if the JPEG compression was on board.

In you want to know more about Huygens DISR, look here: http://www.lpl.arizona.edu/~kholso/overview.htm. Also, check these out for an illustration of how the DISR scientists expected the pictures to mosaic up:
1. http://www.lpl.arizona.edu/~kholso/cameras.htm
2. http://www.lpl.arizona.edu/~kholso/test_images.htm

Note that these appear to show NO JPEG artefacts. I don't know whether Huygens did JPEG compress images or not, but I find it so frustrating that I can't quite make out a lot of things because of those artefacts. Can we expect better???

andersa wrote:the "mountain" looks much too smooth to be real. The dog-ear in the upper right appears to correspond to the one in the lower left, except that the latter gradually disappears after a few frames (I can't guess why). There is another bright artefact in the upper left, stretching from the top of the image well "below" the horizon. I'd blame it on the camera. Has anybody seen a detailed drawing of Huygens showing the design and location of the different imagers (and other sensors)?

The mountain could look smooth due to haze in the distance. I think the upper-right dog-ear is not the same as the lower-left, which is where the flashlight is*. The flashlight fades over time, which is why the white disappears. So, I still think it's a mountain in the background. Current thinking by ESA is that Huygens landed on a flat part within the ridge mountains of the 8km high panorama. I also think that these ridge mountains might turn out to be the Titanian counterpart to Evil Dr. Ganymedes's Ganymedian ridges...

rthorvald wrote:Please excuse me for stupid questions, but does anyone know the temperature of the probe compared to the temperature on the surface? If Huygens was warmer than the material on the ground, maybe what we see is just outgassings from the ground because of it, obscuring the camera lens?

Not a stupid question. No, I haven't seen a temperature for Huygens. Outside surface temperature was 93K, but Huygens has heaters inside to keep its electronics warm. I think they achieve 25?°C.

Yes, I'd forgotten about thermals off Huygens, but I think they don't affect the movie for two reasons:

1. The cameras are low to the ground, and heater thermals would come off the top of Huygens.

2.

maxim wrote:That sound's reasonable. It shouldn't be too could after it's atmospheric ride.

No. Huygens had 2?? hours to cool down during its descent. If Titan's atmosphere is colder at 16km altitude than ground, then Huygens would have been colder, not warmer. By the way - it's a myth that small meteorites land sizzling hot on Earth, they actually land freezing cold: After slowing to terminal velocity above the stratosphere, they drop though it and get chilled.

Spiff.

* If you look at the web page showing pictures of the DISR, you'll see they show the flashlight to the right of the cameras. Thus, I think the Huygens pictures are currently mirrored. Oops.

Spiff,

thanks for your detailed argumentation.

The landing on Titan was clearly a "singular" or perhaps even unique event. What really matters is whether we might put forward some reasoning that might help to decide eventually about the "wet" versus "dry" alternatives!

What information may still be exploited to possibly strengthen or weaken the case? As I stated initially: the "wet" hypothesis is fascinating, but rather void of content unless proven on the basis of scientific arguments....

Bye Fridger

Yes, I understand, but we're faced with a more fundamental problem here. That is, what do we see in this movie?

My proposal that there is "wet" out there is less than a scientific hypothesis. It's a problem with perception, not conception, the latter being where science really works. The quality of the movie currently means that it is difficult to recognise the features, rather than explain them. That's my frustration.

So, I just thought I'd see what eveyone else could 'see'.

If there's no stream, so be it. I think this thread can hibernate, in the hope that non-JPEG piccies miraculously emerge, or some scientist could do a statistical analysis to see if there is significant flickery movement in a certain horizontal band of the movie...

Spiff.

JPEG artefacts in an animated GIF... I'd really like to know how much processing these images have suffered. The 8x16 grid of 32x32-pixel squares making up the image clearly indicates some kind of compression, but are you saying that JPEG was used for compression already onboard Huygens, before transmission to Earth? Maybe bandwidth constraints made it necessary, but I'd say lossy compression is better used for photographing things we already know how they look rather than alien worlds. I want the raw bits, not some automatic removal of "unnecessary" detail.

If you think this is bad, you should have seen some of the Galileo images (which had to be compressed to get any kind of reasonable data return due to the stuck high gain antenna). Some of them are completely destroyed by image compression blocks - you can barely see any detail at all!

If Huygens landed near mountains, this would lend support to the possibility of a stream. Even if methan raindrops cannot make it to the ground before evaporating, that may not be true for the upper reaches of a mountain range. So methane rain might form streams in the mountains which decend into the dry valley below.

Fridger wrote:

Plutonium Dioxide is the deadliest substance known by science.

Lest anyone be confused. Fridger is being ironic here. Plutonium is far from being the deadliest substance known by science. But that didn't stop people who opposed it use from claiming that it was.

wcomer wrote:Fridger wrote:

Plutonium Dioxide is the deadliest substance known by science.

Lest anyone be confused. Fridger is being ironic here. Plutonium is far from being the deadliest substance known by science. But that didn't stop people who opposed it use from claiming that it was.

He's probably not far wrong though - it's still pretty damn deadly stuff. As well as being highly radioactive, it is actually [i]toxic]/i] too, so much so that it takes much less than a milligram of it to kill a human being outright. It might not be "the deadliest substance known by science" but it certainly ranks highly on a list of "most obnoxious substances known by science" .

Either way though, it wouldn't have harmed anyone even if Cassini had blown up, because the RTG containers are very VERY solid and it wouldn't have been exposed at any point.

Oh Great and Evil One,

Nanograms of botulism will kill you in days. Micrograms of ricin will kill you in minutes. A milligram of plutonium might take years to do you in. A ten gram bullet will kill you in seconds. In my book the bullet is deadlier than the plutonium. Also how many people die each year from plutonium. Not many. I'd have to say fire, water, gravity and momentum are some of the deadliest substances known to man.

Plutonium is dangerous but so are cars.

wcomer wrote:Oh Great and Evil One,

Nanograms of botulism will kill you in days. Micrograms of ricin will kill you in minutes. A milligram of plutonium might take years to do you in. A ten gram bullet will kill you in seconds. In my book the bullet is deadlier than the plutonium. Also how many people die each year from plutonium. Not many. I'd have to say fire, water, gravity and momentum are some of the deadliest substances known to man.

Plutonium is dangerous but so are cars.

Walton,

you did get the "under tone" in my post quite right . Yet perhaps not entirely. In fact, I should have put that sentence "Plutonium Dioxide is the deadliest substance known by science." into quotes, since I have copied it from one of the Anti-Cassini activists...

Seriously, in my view, Plutonium is really nasty stuff...no doubt. It's nasty enough to be worried even about small quantities that potentially could get out of control.

On the other hand, there are always risks that potentially could effect large scale damage and that we will never be able to eliminate completely. So in such cases, I consider it crucial to honestly and openly inform the public beforehand about the estimated probablility for an accident and the possible implications. In most cases it will turn out that after honest and detailed information the public is willing to accept that risk if the issue is really well motivated.

In my science community, there are plenty of such examples.

Bye Fridger

wcomer wrote:I'd have to say fire, water, gravity and momentum are some of the deadliest substances known to man.

And don't forget beds! Deadliest instrument ever! Millions and millions of people died at its exposure!

Sorry, old joke...