Liquid Lakes on Saturn's Titan (APOD 7 Feb 2007)

[harry]

Hello All

Liquid Lakes on Saturn's Titan
http://antwrp.gsfc.nasa.gov/apod/ap070207.html

Why would some regions on Titan reflect very little radar? The leading explanation is that these regions are lakes, possibly composed of liquid methane

If it's not Methane could it be water, created by under volcanic activity.

Aichip would know,,,,,,,,,,,,,,,,,,,,,

[Ditch]

Future observations from Cassini during Titan flybys will further test the methane lake hypothesis, as comparative wind affects on the regions are studied.

Effects, not affects.

[harry]

Hello Ditch

No ! its affects not effects

Read it again.

I will ask my wife she is a English Teacher.

ooops she is asleep

[orin stepanek]

affect is correct.
http://owl.english.purdue.edu/handouts/ ... lprob.html
Orin

[aichip]

Since the temperature and pressure on Titan is very close to the triple point of methane, and we also know that methane is abundant there, it seems to be the most likely material for the lakes to be made of. It is also thought by many scientists that other materials such as ethane may be present. Ultraviolet light from starlight and sunlight can polymerize methane into ethane and release traces of hydrogen in the process.

We also see some evidence of a "water table" from the surface images, in particular the moat rock in the foreground of the images. It has a ring in the soil surrounding it, as if some fluid has boiled up from beneath. This is also not unreasonable, as we know that some fluid has been working the surface and created the apparent lake beds, rivers, and erosion we see. So a fluid that can change state from liquid to vapor would be the most likely agent, and methane fits the profile in all cases.

Water is not very likely on Titan. While we do expect that some "geological" heating occurs in the moon due to the flexure from tidal forces (created by Saturn), we will not see a great deal of water because of the extreme cold. It may be liquefied underground and erupt from time to time, but it would then freeze, forming the equivalent of gravel or rock. We may find that a lot of the soil is ground up water ice particles mixed with sand and rock.

Since water is more or less a mineral under the conditions that prevail on Titan, this is an extrapolation based on what we see there and know about the material properties. All in all, it is a very fascinating place. Also, consider that if there are hot reservoirs of liquid water underground, there could in fact be life- but it probably would not survive being deposited on the surface. And it would likely be only bacterial. And hot is relative here; meaning that if this hypothetical water did exist, it would need only to be above freezing, not necessarily near boiling.

And to the point of the word in question, for the usage we see the word "effects" is more appropriate. It is a noun, not a verb. "Affect" is a verb, representing the action as in "the wind could affect things." "Effect" is the noun, showing what wind might have created- "wind effects". This is a subtle point for many, and easily mistaken.

[ta152h0]

how fast is Cassini flying over Titan ( ground speed ? ) i realise it is a sphere so perhaps the question should be rephrased to say how fast in relation to the center of Titan when perpendicular ?

[aichip]

Looking at the orbital data, Titan is moving about 5.6 km/sec in its orbit, and Cassini is doing about that- although its speed varies greatly since its orbital path is a complex elliptical one. If we look at the angle of approach, it is likely traveling at about 1.8 kilometers per second or so relative to Titan.

[orin stepanek]

Future observations from Cassini during Titan flybys will further test the methane lake hypothesis, as comparative wind affects on the regions are studied.

Effects, not affects.

You are quite right. I misread the statement as [wind affects the regions] as compared to [wind effects on the regions].
Orin

[harry]

Hello All

Thank you Aichip, you are magic.

We are so lucky to have you on this site.

[nicktoop]

They don't look at all like lakes to me...they look much more like scum on a lake/sea. The crucial thing, of course, is do they change?
It seems to me quite possible that methane lakes could be covered by a scum of complex organics.
The same applies to the original probe pictures which appeared to show drainage channels into seas. We were then assured they couldn't possibly be seas because the radar reflectance was wrong....why not more scum?

[iamlucky13]

Do you mean it looks like scum because of the texture? Remember this is a radar reflection off the surface and it's a view 150 km wide. Color and texture can be deceptive, because of the scale and the fact that they don't represent what the ground actually looks, but rather varying strengths of radar return.

Of course, that doesn't discount the possibility of there being some sort of surface scum, but the radar isn't likely to show it if there is.

I don't think the Hguyen's pictures showed liquid, just geologically features that looked like drainage canals. If they are, the explanation for the radar returns of the area were that the canals were dry at the time. There's been some speculation that Titan undergoes "dry" and "wet" seasons.

[orin stepanek]

http://en.wikipedia.org/wiki/Image:050114huygens1.jpg
This is from hyugens which I think really looks like a lake.
Orin

[nicktoop]

Do you mean it looks like scum because of the texture? Remember this is a radar reflection off the surface and it's a view 150 km wide. Color and texture can be deceptive, because of the scale and the fact that they don't represent what the ground actually looks, but rather varying strengths of radar return.

Of course, that doesn't discount the possibility of there being some sort of surface scum, but the radar isn't likely to show it if there is.

I don't think the Hguyen's pictures showed liquid, just geologically features that looked like drainage canals. If they are, the explanation for the radar returns of the area were that the canals were dry at the time. There's been some speculation that Titan undergoes "dry" and "wet" seasons.

Hi,
Thanks for the reply.

I meant it looks like scum (or floating crust) because of the apparent absence of any drainage channels... just like bubbles in a bath. Several features look like dislocations in a crust. I am not concerned about the colour but, as regards the apparent textures, are you saying that a complex hydrocarbon crust would be invisible to the radar frequencies used?

I realise that the structures which looked like drainage channels in the initial probe pictures were dry but my understanding was that if they were directed towards a "sea" then this "sea" should have appeared to radar rather like a mirror tilted away or else show wave reflections and so it could not be a sea after all. However, this would not be so if the "sea" was covered by a roughly textured crust.

[iamlucky13]

Ahh, I see. I suppose whether or not a crust would reflect the radar signals depends on the frequency of the radar, the molecules in question, and the thickness of the crust. I don't know particulars about any of those.

I also don't know if the radar image in the current APOD has the resolution to show the interesting channels seen from the Hguyens descent imager, much less surface waves.

I read somewhere, although I don't recall where now, that not only do some researchers suspect the channels were dry, but the "sea" might have been, as well...perhaps due to long-term changes, or perhaps due to seasonal drying.

I think this kind of study is hard, because we know what we want or expect to see, but we also don't want to trick ourselves into seeing what's not really there.

[ta152h0]

Maybe the Titanians sprayed some dust on these lakes, knowing Earthoids would be sending an observation craft, thereby hiding their methane skiing activities In advance to moderators critique of this post, I apologise .................................NOT ! 8)

[kovil]

I would enjoy to have some experience reading radar photos of various surfaces, lakes, forests, dry lake beds, savannas, marsh/swamp, sagebrush covered desert, glacier ! , sea packice, in order to see what kind of vibration/variation signature they leave.

Perhaps, Amara Graps and the Wavelet Analysis Team could help with this problem of reading the photos.

Great food for thought photo, btw APOD !

[bystander]

Future observations from Cassini during Titan flybys will further test the methane lake hypothesis, as comparative wind affects on the regions are studied.

Effects, not affects.

You are quite right. I misread the statement as [wind affects the regions] as compared to [wind effects on the regions].
Orin

maybe not, according to wiktionary,

Do not confuse affect with effect. The former is used to convey the influence over existing ideas, emotions and entities; the latter indicates the manifestation of new or original ideas or entities.

http://en.wiktionary.org/wiki/affect

[harry]

Hello All

Great, now we got effect and affect out of the way.

What were we discussing?

Oh yes!

Methane

How and when was it formed?

[aichip]

I have maintained that the methane came from the protostellar nebula. Consider that any water ice that might be present would trap methane in the form of a clathrate and keep it there. When Titan formed, that methane would be stored in the ice and as long as it remained frozen, it could not escape.

Now, since Titan is flexed and internally heated by tidal forces from Saturn, the interior can release methane over long periods of time, and that is the source of renewal for Titan's atmosphere. It seems odd that numbers of planetary scientists have a hard time explaining where it comes from when this mechanism is simple and sounds reasonable.

Add the fact that around a gas giant, the orbit of a moon creates a gas torus that shares its place in the gravity well, and you can see that anything escaping is more or less bound to return, since sunlight does not provide a great deal of energy to aid that gas in escaping. Closer to a star, light pressure helps to remove voltaile elements to the outer solar system. At the distance of Saturn, even at noon the brightness of sunlight is comparable to that of the full moon on Earth.

[Jon Ebert]

Manned spaceflight was exciting running up to the Moon. But now we need to get some robots on the surface of these other worlds to answer these questions. I hope we stop screwing around with the desire to fulfill science fiction romanticism. Humans on the surface may be romantic but robots on the surface are safer, cheaper, quicker and can collect and transmit incredible stuff. Then we can move on to boldly go where no one has gone before. I'm having a real difficult time with the idea that we need to put humans back on the Moon and then on Mars. They are boring places. Titan and Io and lots of other worlds are much more exciting. Our robotic technology is improving so much that we could be moving through the solar system much quicker. Off topic? Maybe but I'm reading all these theories about what that is on the surface and I'm thinkin; wouldn't it be great if we had a Mars rover type robot that could just pull-up to the lakeshore and take a sip!

JE

[iamlucky13]

I have maintained that the methane came from the protostellar nebula. Consider that any water ice that might be present would trap methane in the form of a clathrate and keep it there. When Titan formed, that methane would be stored in the ice and as long as it remained frozen, it could not escape... (snip)... It seems odd that numbers of planetary scientists have a hard time explaining where it comes from when this mechanism is simple and sounds reasonable.

Perhaps they haven't figured out how the protostellar methane would have formed? Methane breaks down over time by ionization from UV.

The idea for the release of existing trapped methane certainly sounds feasible, though.

[ta152h0]

Ultraviolet light been around longer than visible light ?

[iamlucky13]

Manned spaceflight was exciting running up to the Moon. But now we need to get some robots on the surface of these other worlds to answer these questions. I hope we stop screwing around with the desire to fulfill science fiction romanticism. Humans on the surface may be romantic but robots on the surface are safer, cheaper, quicker and can collect and transmit incredible stuff. Then we can move on to boldly go where no one has gone before. I'm having a real difficult time with the idea that we need to put humans back on the Moon and then on Mars. They are boring places. Titan and Io and lots of other worlds are much more exciting. Our robotic technology is improving so much that we could be moving through the solar system much quicker. Off topic? Maybe but I'm reading all these theories about what that is on the surface and I'm thinkin; wouldn't it be great if we had a Mars rover type robot that could just pull-up to the lakeshore and take a sip!

JE

A little off-topic, perhaps, but I see your context. We're still quite a ways off from having significant robotic capability for accessing Io, Europa, or Titan. The conditions on those bodies is quite a bit different from Mars (a lot colder, and very different surfaces/atmospheres for each). Note for example that Hguyens only ran for 3 hours and was entirely dependent on Cassini to relay its data. Even the Mars rovers or the upcoming Mars Surface Laboratory only have a range of a handful of kilometers.

Still, we're ever farther from the ability to land a man on Titan, so my points above are moot in relation to your post.

As for manned exploration in general, there are many tasks a human can do far more efficiently than a robot (Even the lead scientist for the Mars Rovers seems to whole-heartedly concur), and the motivations for manned space exploration are not soley limited to considerations of data-returned/dollar invested. If we are to expand beyond the earth, which I daresay most people feel we should (reasons including pioneer spirit, human survival, the need for challenges, national pride, etc), we obviously need a manned space program.

[harry]

Hello All

tai5ho said

Ultraviolet light been around longer than visible light ?

Is that a question or an answer.


Both are like the chicken and the egg. They are part of the EM spectrum.

Actually the answer to the riddle what came first the chicken of the egg has been solved.

[Dr. Skeptic]

Ultraviolet light been around longer than visible light ?

The full light spectrum was created during the "re-ionization period" about 300,000 years after the Big Bang. Radio, IR, visible, UV up to gamma rays are all electromagnetic waves able to be generated upon the first stable atoms forming.