RAW TRANSCRIPT -- NOT YET REVIEWED FOR CORRECTIONS BY CASSINI PERSONNEL

**FTS-NASA-VOICE**

**Moderator: Trina Ray**

**November 27th, 2007**

**1:00 pm CT**

Coordinator: This is the operator, I just wanted to inform all parties
today's call is being recorded, if you should have any objections you
may disconnect at this time, you may begin.

Amanda Hendrix: Thank you. Hi everybody, this is Amanda Hendrix and I'll
be hosting the Charm telecon today, welcome. This is the November 2007
Charm telecon and I'm pleased to introduce Dr. Karl Mitchell of JPL and
he will be talking us today about the lakes and seas of Titan,
observations from Cassini RADAR.

Dr. Karl Mitchell studied physics with space science and technology at
Leicester University in the UK and where he received a bachelor's degree
and then got a Masters in remote sensing at the University of London
where he first started doing planetary geology.

And received his PhD in environmental science from Lancaster university
in the UK studying the physics of explosive volcanic eruptions on the
Earth and Mars, and has been a post doc at JPL a NASA post doc since
2005 after doing a post doc at Lancaster University.

At JPO he's working with Rosaly Lopes on the Cassini RADAR team working
on radar data of Titan of volcanoes and lakes. And so today he's going
to talk about some of his latest results.

And so with that I guess we'll have you go ahead and start Karl.

Dr. Karl Mitchell: Okay, thanks Amanda. I take it you can hear me at the
moment Amanda?

Amanda Hendrix: I can hear you.

Dr. Karl Mitchell: Okay, I'll assume everyone else can. Okay, I'm going
to show you surfaces, well water's pretty much a new world but some of
you will have looked at it before, I say new world because before
Cassini Huygens arrived we really had only had tantalizing hints of what
Titan's surface might look like.

And now data is already out of the magnitude better than previously.
This isn't just the result of my work, this is the result of a very
large team of scientists not only here in America but from multiple
countries including Italy and France.

And so I give you credit to all of my associate on the Cassini RADAR
science team.

For decades before Cassini reached the Saturn system we had this concept
of Titan being a wet world. This was largely based on observations from
Voyager where we saw that there was an ethane atmosphere and telescopic
observation.

As early the 1980's scientist such as Jonathan Lunine for suggesting
that Titan had oceans or anything based on spectroscopic data, but also
on models of how the climate should work.

More recently remote sensing observations seemed to rule that out, at
least around the equator which is where they were suggesting there might
be before, but we still went into the Cassini Huygens mission thinking
there should be some complex hydrological, (methanological) system,
probably with standing bodies of liquids and channels.

Now if you could move on to the second slide. However initially at first
Cassini didn't show us lakes and seas, there was plenty of evidence that
the (unintelligible), and I've got a picture of Cassini's hydrocarbon
cycle was emerging involving methane rain, possibly hydrocarbon, nitro
or organic snow and a whole bunch of complex chemistry.

Now on this slide you'll see some of our early ideas on how this all fit
together. You'll see that there's some evidence for cryovolcanic
eruption, something we think of as a dome, like the features on Venus on
the left hand side there.

Providing methane to the atmosphere, there are channels up at the top
which are carved into the surface which we think of as being mostly
waterized, but possibly many other things there as well.

High ridges that have been excavated in some way by erosion which
rainfall may have played a part, and some dune like forms, or dunes
which were separated somehow, aggregated into small particles, possibly
snowed out from the atmosphere, were probably snowed out from the
atmosphere.

But we didn't actually find any seas except for these massive sand seas
or as (unintelligible) puts it. And so there was a question mark still
hanging over this idea of where the standing bodies of liquids were,
which is hard to rationalize with the climatic models which all
suggested there should be standing bodies, unless there was a massive
ray of replenishment of methane outside the atmosphere, because you need
to balance the amount of methane in the atmosphere with the amount of
methane on the surface.

So a possible explanation was found for this very recently, during the
Cassini Huygens mission, by Giuseppe Mitri who was a planet PhD student
at the University of Arizona and is now working with me.

Inspired by climatic modeling by kind of (moibar) was suggested that low
temperatures and high variability in the polar regions could result in
lakes, a variable side in those polar regions instead of at the equator
which is where people were previously looking.

And on that side we hadn't actually had any images of these polar
regions. Evaporation of these lakes would be able to explain the
atmospheric, the relative humidity in the atmosphere as long as they
covered at least .2 to 2% of Titan's surface.

So not a huge faction of the surface compared to say the seas on the
earth. I was only just becoming aware of the one we had our first polar
fly by. Many of you will have seen the initial paper and press releases
showing dark patches on the surface of Titan.

And we hope to convince unsuspecting world perhaps that these were
finally the standing bodies of liquids everyone was talking about. Next
slide please, thanks to massive improvements in image processing
technology we have this splendid image of Titan.

Actually no, this is actually near where I used to live in the UK. It's
Titan's latest district is somewhat different, this is the lake district
in the Northwest of England, if you just flip on to the next image and
the next slide I will replace it with something like what we actually
saw the first time.

There are more lakes for a start on Titan. There is an incredible
density of lakes up there. As we reported in nature the T16 near polar
flyby alone would build about 80 radar dark patches, and I use the
expression T16, we used this within the team and within Cassini, T
standing for Titan, 16 standing for the number of orbits, or the number
of the flyby by which we passed it.

So this would have been technically our 18th flyby time but the first
two were not given numbers. Now these features we were seeing were by
far the darkest surfaces that Cassini RADAR had ever seen, so radar
really wasn't being reflected off the back half of the radar instrument.

The radar instrument looks sideways so it needed a certain amount of
roughness in order to reflect back or float this angle into the radar,
and clearly this didn't have it.

The other thing that's making it dark is it's been absorbed, and we know
from studies in the lab the 2.2 centimeter wavelength radar which is
what we're seeing, which is what we're using for Cassini RADAR is
absorbed from mainframe as well.

And it's semi-transparent that way.

Amanda Hendrix: Karl, I have a question.

Karl Mitchell: Yes.

Amanda Hendrix: From two slides ago when you say that the lakes were, I
don't know if they were predicted, but the climate modeling work of
Mitri and all, suggested that low temperatures and their high
variabilities, do you mean high variabilities, temperature variability
like due to seasonal changes?

Karl Mitchell: Yes. Seasonal changes near the poles resulting in a
greater temperature changes and seasonal variability at the equator.

And that results in changes in precipitation. IF the temperature changes
then you get spontaneous precipitation in the atmosphere, so more
rainfall, yeah.

Amanda Hendrix: Okay, thanks.

Karl Mitchell: Okay. Let's see, where am I, next slide please. This
isn't going to work for me, it's not going forward, ah here we go. What
I'm going to do now is take you through the T16 radar swath as I
originally saw it. I'd only fairly recently joined the team so this is
all fairly new to me.

And then we saw these absolutely wonderful features for the first time.
This slide is a little bit animated so I'm hoping everyone here has the
PowerPoint file, the PPS, apologies to anyone that doesn't because it
really doesn't translate to PDF.

So the first thing you'll see the entire radar swath near the top of the
screen. That's approximately 120 kilometers, so 75 miles or so at this
point. There are thousands of kilometers along the swath, and you can
normally see the little black patches near the center.

Well out near the center was very close to the North pole, I think it
got up to 83 degrees, something like that at closest approach. So this
is going over the pole, the narrowest bit near the North Pole. Over the
arctic I should say.

In total I counted about 77 lakes in this area, 77 dark patches and we
interpret them as lakes. And then if you click on the next slide you'll
see a zoom in section, so you'll start to get a better view of these
lakes.

And then if you click one more time, you should see almost the full
resolution there. And you'll see that we've got all these little dark
features, mostly irregular, some of which seem to have rend.

The illuminations in the radar from the top of the image, that can see
the right facing area, that's quite often a slope faced into the radar
instrument. A dark surface is a wave, so all of these are depressions,
these dark areas here.

So in this swath that's about 130 kilometers, so about an 18 mile from
top to bottom. So many of these lakes are tens of kilometers across,
down to a few kilometers across.

You can only see features down to a few hundred meters in the slides
here. So some are circular or near circular which was interesting
because they look somewhat like volcanic calderas on the earth or
something like crater like in some of them.

We've got similar size as well, and there's one or two that look like
they might consist of several circular features, with a fairly big lake
to the left of the center of the screen there looks like it might
perhaps consist of multiple circular areas.

Several are steep sided with clear rims. If you go to the next one,
we'll pan along the image as we go through, you see what looks like some
sort of large basin. Now this area here, this dark patch at the bottom
of the screen, it's purely due to surface characteristics.

So it's going to be darker to the radar than the rest of the scene,
although not quite as dark as a lake, though it shares some features
with the lake.

It could be that this is actually some sort of volatile residue that
happened in the past, the jury's still out somewhat on that one.

The next part of this scene you see some of the darkest lakes that we've
imaged. These at times go below the ability of the radar instrument to
tell any brightness variation on the surface, more noise than
(unintelligible).

Those are extremely dark, and clearly a completely different material
from the rest of the surface. The resolution's the highest in this part
of the scene and we start to see a channel feeding into connecting
lakes. In some places where the lake contents are fairly bright we also
see some channel structures on the floor, which on the slide probably
once show very clearly that I'm going to show in more detail in a later
slide.

That's because as I said earlier, liquid methane and ethane are the main
candidate materials for these lakes are semi-transparent to radar, so
it's a bit like looking down on Titan from space in the same way that
you look down at the coast lines from satellites on the earth, you see
the sand of a beach going under the water and slowly becoming green and
then fading into blue and then black.

Okay, the next slide, or the next step please. This was the best example
on this scene of what we think of as perhaps a drained lake. If you go
to the (just to the left) of the image and it's a bit difficult to make
this out, you'll see that there's a fairly large crescent shape formed,
and at the bottom left of that, there's what looks like a depression
with a clearly defined, fairly clearly defined rim around it.

What we've interpreted was previously one of these dark things which
flowed into the currently dark feature during some sort of drainage
event or flow back or perhaps slowly evaporated a bit like an evaporate
basin on the earth and desert like regions.

It's morphologically similar in some ways to the other beaches which
leads us to think it is a lake rather than some other unconnected
depression.

And the final one of these zoom ins you'll see at the bottom of the
image it looks like one of these nested structures I talked about,
multiple circular depressions that look a lot like volcanic calderas. In
fact if we saw this structure on any other extraterrestrial planet, we
would probably immediately jump to the conclusion that these are
volcanic calderas.

And the whole idea is that you can have cryovolcanism on Titan which is
much like volcanism on the earth but rather that erupting magma, what
you are erupting is water with something like ammonia, something that
works as a antifreeze for this cryomagma.

Amanda Hendrix: So are these depressions that might not be deep enough
for liquid to accumulate in them?

Karl Mitchell: It's possibly the case, it's possible that it's drained
or evaporated since then so the lake is not filled to its peak as well.

Amanda Hendrix: Okay.

Karl Mitchell: So anywhere else we'd say that that was probably a
volcanic caldera, but there may be alternative interpretations for
Titan. Titan is a very complex world, and I use the word world not
lightly, I think of a world as a place with, as a planet with a lot of
places, or a moon with a lot of places and things that people can relate
to rather than just some sort of dead, dry, (unintelligible) like body.

Titan has certainly shown that it's got a lot of variation. It's got
most of the geological processes to work on here, so I very rarely use
the word world for planets.

Mars I think of as a world, we got features like Olympus Mons, certainly
Titan's been capturing people's imagination.

If you click once more you'll get a zoom in of that structure that looks
like volcanic caldera just to give you a bit more of what that's like,
so that's a few miles across from top to bottom, maybe 10 miles, 15
miles, something like that.

So that's a pretty large structure, perhaps similar to Kilauea volcano
in (unintelligible). Okay on to the next slide. The question we first
have to ask ourselves was are these actually liquid lakes at the moment.

We were convinced that these have been lakes. There were channels
feeding them, there were shorelines that looked lake like, we had
predications that there would be lakes in these areas.

There hasn't been currently, are lakes. I mean we see features that
looks like a volcano, it didn't necessarily mean it's active at the
time, and the same is true with lakes.

Clearly the fact that they were extremely dark was immediately something
that made us think yep, these must be liquid. But that doesn't
necessarily have to be the case.

If you click on the next one, you'll see from more of this morphological
evidence of the channels here and then straight on to the next one, the
third one of these inset images here is an idea of the radar max scatter
of the lake.

(unintelligible) there was extremely low microwave reflectivity so
extremely, the radar isn't microwave length.

And the top of this radar reflectivity goes way beyond, way below the
(unintelligible) as we call it of the image. Typically the surface of
Titan has a normalized radar cross section in the order of minus ten to
maybe minus eight (unintelligible), and in places on the rest of the
planet it goes down to say minus (unintelligible).

But here you'll see that these lakes go way below anything else we've
seen. So that was our first very strong piece of evidence that they were
currently active.

But we were able to come up with alternatives that could possibly
explain this, either a very small or dusty surface or some sort of wet
mud, something like mud flats could potentially produced features that
were this bright, this dark I should say.

Although there were more arguments in favor though consistent with
present day conditions, there's no reason to think that the lakes
wouldn't be liquid filled because the planet is actually
(unintelligible).

And there was also this dichotomy of these dark lakes and the bright
lakes or the drained looking lakes. And again this is zooming into that
image that I tried to show you earlier with arrows now to highlight
where we think this drain like feature was.

So there was lots of evidence but nothing really clinched the deal on
this (thing), no smoking gun. On to the next slide please.

Well very quickly after this T16 flyby we had two more. And I'm showing
you here in a polar projection, this scene is, let's see if I can work
this out, it's a few thousand kilometers across, something like the size
of Canada here that would be about. So from 65 degrees north and 5
degrees stepped all the way up to the pole.

And as we built up this scene we felt it to say that the lakes had
different characteristics in different areas, and this polar overview
shows it quite well. You'll notice that the lakes mirror the pole and
towards the bottom of this image they seem to get bigger.

Quite so in these areas where the lake's much larger, they tend to be
flatter, they don't tend to have sort of (unintelligible) in size when
the, except right to the bottom when you get down to the lower latitudes
again.

So variability across the scene so we were very excited as to what would
happen as we built up this polar region more and more.

Also right at the bottom right of the scene you'll notice that there is
an unusual shaped lake there which I'm going to zoom in later which
shows a more rugged coastline, something reminiscent of Lake Powell
perhaps or the fjords of Sweden, lots of jagged shoreline.

And yeah, quite a lot of variation. I'm going to go on to the next...

Amanda Hendrix: Karl?

Karl Mitchell: Yes, please?

Amanda Hendrix: Before you move on, I think you said this but I'd like
to ask again now that I see these three together here. I think that the
middle swath is the T16 that you just went through in detail?

Karl Mitchell: That's correct.

Amanda Hendrix: And now that I see these three together, that dark area
in the middle, a little bit above the middle, there, it does look
different from the other lakes, what did you say about that one?

Karl Mitchell: Well I was wondering if it was something that was an old
impact crater that was once filled with liquids but is now evaporated
and has left some sort of deposit behind. Obviously it was suggested
that it's filled with hydrocarbon snow because it's a topographic low.

We don't really have a firm conclusion on that but it's definitely
darker than most of the surface but not quite as dark as the lakes. So
we don't really have it as a candidate for a major liquid body.

Amanda Hendrix: And you, but it could be an impacted crater that filled
in?

Karl Mitchell: It could well be, yes.

Amanda Hendrix: Are there other impact craters in here that could have
filled in that you think, or?

Karl Mitchell: Well we don't see many impact craters on the surface of
Titan, it's quite interesting, it suggests that the surface of Titan is
quite young. In these scenes there is nothing that I would say
unambiguously is an impact crater including this basin. It may well be
something else.

Amanda Hendrix: Right.

Man: Karl?

Karl Mitchell: Yep.

Man: I'm a little lost, what slide number are you on?

Karl Mitchell: Slide number six.

Man: Six?

Karl Mitchell: Six.

Man: Okay, thanks.

Amanda Hendrix: Just also for everybody on line, do be sure that you're
following along in PowerPoint in slideshow mode and that way you can...

Karl Mitchell: Oh yeah, yeah that's important, they have to be in the
slideshow mode. There's quite a lot of the individual slides have intros
come in and change.

Man: Karl, could you also describe the title of these slides for those
of us who printed it out and don't have any page numbers.

Karl Mitchell: Okay, the title of slide number six is Flybys, page
number six. And I'm just about to go on to post T16, page number seven.
So right, T19, which was the third north polar fly by, the second one
didn't really show us all that much other than how far south some of
these lakes were.

It revealed this new morphology and you'll see an image at the top right
of this slide hopefully if you're on the PowerPoint showing larger lakes
with rugged coastlines as I said like Lake Powell or the Scandinavian
Fjords.

And we're seeing growing evidence that we're seeing through these
liquids, as I said earlier methane is transparent, but if you right
click on your PowerPoint and go backwards and forwards you'll be able to
see the contrast changing on this image.

What hopefully you'll see is there's a channel that leads in from the
bottom and then seems to wind its way through some of this lake
material. So again we're probably seeing through at least several meters
that unfortunately the degree of transparency of liquid methane and
ethane isn't actually very well known.

We're trying to get to it with lab measurements, I've got a colleague
in, (Kayou) his name is who is doing various lap measurements in order
to understand how far that you might be able to see through these bodies
with radar.

But we know that it must be at least the order of a meter, down to maybe
100 meters that you can potentially see through, so if you see a
surface, a subsurface structure at the bottom of the lake assuming that
they're liquid filled, which is a very strong case now, then you're
probably seeing down to the depth of a few to maybe 100 or so meters.

Okay, next image, this is zoomed out a little bit and back from that
image and so right at the top you see that channel that lead into that
lake and basically what we've got here is a very long river valley, many
hundreds of kilometers so maybe a few hundred miles long leading from
triangular region, I hope you can see that about 2/3 up on the left, a
depression that some of us have interpreted as (unintelligible) another
drained lake structure.

Overly into that liquid body and you'd also see a lot of these features
here that we've also interpreted as empty lakes or drained lakes all the
way through the rest of this scene. In certain areas they seem to
cluster together and they're much more apparent than in that original
T16 flyby.

Now by the time we got to this T19, this is 100 kilometers across, this
trip I should have said earlier, by the time we got to this T19 flyby
we'd actually seen about .2% of the surface of Titan was covered with
these dark patches.

Now you may remember from earlier I mentioned that there was a study
that said there had to be .2 to 2% of the surface covered with lakes in
order to explain the methane humidity in the atmosphere.

And so we've hit that critical level whereby it was more consistent
again with this climatic modeling.

Amanda Hendrix: Karl is that .2 to 2% above a particular latitude then?

Karl Mitchell: No, you just needed .2 to 2% on the entire planet, and
that's at least .2 to 2%, so 10% would be okay, but that was the bottom
end.

Amanda Hendrix: Even though there's more expected in the polar regions.

Karl Mitchell: Yes, covering the entire planet. So by this time we
observed a fair fraction of the surface of the planet and we were
starting to get to that 2% level.

(Ken): I've got a couple of questions, this is (Ken) in North Carolina.
First off, the karst you mentioned on slide I think it was five, about
karst topography, what is the surface at this point made of, is it
mostly water ice? I mean what are we talking about here?

Karl Mitchell: I'm actually going to go into that a bit later so I'm
going to defer most of that question. When we, the karst interpretation
is something that came up as an alternative to the cryovolcanic
interpretation on some of these depressions. And I will talk about that
in more detail, but the surface is primarily water ice the crust is
primarily water ice.

But there's a lot of evidence of something like solid hydrocarbons or
(nitriles) organics, smooth out onto the surface to actually process it
in some way, and so that's somewhat more soluble than water ice. Water
ice under Titan conditions is not very soluble and liquid methane would
not dissolve, at least not over, anything over billions of years to any
degree.

Man: And then the second question I have has to do with the physical
properties of methane itself. When it freezes, would it float or sink on
its liquid counterparts?

Karl Mitchell: Okay, liquid methane if it were to freeze would sink.
However Titan's surface temperature which is at the order of 95 Kelvin
also at 1.5 bars, we don't think it actually goes below the liquid of
methane or it goes to about the liquid of methane.

And so we really don't expect it to freeze. The other thing is that when
we've got methane on the surface, the chances are there's a component of
ethane and perhaps a component of dissolved nitrogen, which would also
deflate the liquid further.

And so we really don't think it would freeze under any circumstances
unless you've got some sort of curious local conditions.

Man: And have you got a feel for how tall some of these features are, or
what's the range of height and depth here as we're looking at it?

Karl Mitchell: Yes, I can't give you any specific examples on any of
these images because we really don't know how very accurate, but we do
have some (unintelligible) and the variations on a really local scale
are on the order of a few kilometers.

So this is suppressed relative to at least mountainous areas on the
earth. Some of these depressions here that most likely of the order of
hundreds of meters to a few kilometers maximum but most likely just
hundreds of meters of depth for the really clear depressions.

Okay, so I've got one more click. The question is, is anyone getting
convinced by the evidence or is anyone not convinced by the evidence
that these are liquids? This is something that I've been asking in lots
of talks before.

Because really you have to convince a fair amount of the community that
these are liquids before you can go on and just assume that they're
liquids and use that in your models.

Otherwise fusion models are along with being liquids are difficult to
justify in many ways.

But we're now, by this state we were fairly convinced and we're 99.9%
sure that these were liquids, but we hadn't completely eliminated the
possibility that they weren't liquids at the moment.

But we were getting there. Okay, next slide, and this is a big leap
forward now. This is a slide called one year at Titan's arctic, slide
number eight, and it's a color mosaic of the North Pole or the north
polar region of Titan from 55 to 90 degrees north.

The color is synthetic. Basically colorized the lakes in blue but we've
done it based on climate. And so it's a fairly good indicator of where
we think the lake materials are. Clearly there's a lot of room for error
here at this input threshold.

But it is pretty striking how well dark areas match up to lake like
morphologies. So this is 2250 kilometers wide, consists of nine
synthetic (unintelligible) radar images in two different modes, and
we've imaged here almost 70% of this north polar region.

There will be little feature coverage from now on, at least for the next
year or so during the primary and extended mission. And so this is it
for quite a long time, this is state of the art.

And you'll notice the really striking thing about these new scenes that
we've added is the extreme scale of these lakes. If you go into this
right quadrangle, you'll notice a very large near circular lake.

It's actually 100,000 square kilometers in area, established area. That
is larger than anything that we call a lake on the earth as I understand
it. Most things that are approaching that in size or beyond that in size
would be called seas.

So we nicknamed this the Black Sea, it will have an official name at
some point in the near future. I think that everyone that's new has
settled on the expression sea for these large bodies, they're certainly
somewhat different in morphology so distinct from the lake.

And they are unmatched on the surface of any other planet except the
Earth obviously. One of the other teams the ISS team imaging systems
site, something like that, I'm terrible with acronyms sometimes, caught
a glimpse of this dark sea on the bottom right quadrangle here that
we've got a couple of images showing part of.

That seems to extend from west pole to south in this pole region
according to their image data which is much below our resolution, it's
fuzzy but you get this image of a black blob down there, sorry I haven't
got a nicer one of this but you can look it up on the JPL photo journal
website if you are feel inclined.

That's almost certainly much larger than 100,000 square kilometers, so
we're talking about something that's again is unprecedented on any
planet other than here.

Amanda Hendrix: Karl? Do you, it looks to me like all of the large seas
are over in, you know kind of one longitude range on the other side it's
mostly the small lakes.

Is that real do you think or any...

Karl Mitchell: I do think that's real, I said earlier that the lakes
were clustered. And I'm wondering if it's something like Minnesota, the
Great Lakes, something like that, for those of you who have been to
those parts of America, you've got these massive lakes and quite a lot
of the time fairly near the edges you've got these areas of karst like
terrain.

So the terrain that has been chemically dissolved and withered away. So
perhaps in the topographic, on a slightly topographic lower regions
you've got these broad great lakes or seas, and then in the
topographically high areas just around the shores you've got quite a lot
of drainage but the formations of these very small lakes.

Certainly that does seem, it does take up the north, we're waiting for
south pole data and I'll show you that first glimpse of south pole later
but from this one thing which is really only one data point, there does
seem to be a dichotomy from one hemisphere to the other with these large
sea like features and these small clustered lakes.

Okay, on to the next slide please, next to the second of these ones
titled Titan's Arctic, it's just a glimpse of some preliminary mapping
efforts. Perhaps this highlights more of the variation in surface
feature types around here.

The yellow ones on this scene, the yellow lakes as we've classified them
are the drains feature, the green lakes are small, irregular normally
with a slight rim. There's a few dotted little blue ones in there which
are circular, look something like a volcanic caldera and we can't
eliminate the possibility that some of these depressions are volcanic
calderas.

But to have this entire region, all of those green ones being volcanic
calderas is starting look by this stage pretty unlikely.

I think that we have to start thinking of alternative hypothesis and
when it comes to clusters, major clusters of dozens, hundreds of lakes,
thermokarst which is melted areas of permafrost on the earth or karst
which is dissolved regions of limestone or other water soluble materials
on the earth.

But the real analogs, the main candidates for some process that could
explain this picture.

On to the next slide, now the next slide is a movie. I'm hoping that
those of you who have PowerPoint will have the version that's got the
embedded movie and is viewable.

If it's not there's a weblink on the download slide, hopefully for those
of you that couldn't view that would have downloaded the link as well.

Man: Yes, actually I went out to the movie link and both the large
format and small format it says that that page is unavailable.

Karl Mitchell: That page is unavailable, oh, I had no trouble
downloading it earlier, but oh dear.

Amanda Hendrix: Did other people have problems downloading it?

Jane Jones: Amanda, this is Jane. I went onto the website and for people
who, I couldn't get it off the charm page, but if you go to the Cassini
website and go to latest videos you can get it there.

So unfortunately it doesn't, it seems to, I wasn't able to do it on the
PowerPoint or from the charm link, but.

Amanda Hendrix: Well hang on, so if you go to Saturn.jpl.nasa.gov, is
that where you mean Jane, and then you can go to multimedia?

Jane Jones: Yep.

Amanda Hendrix: Okay, so I go to Cassini then I go to multimedia.

Karl Mitchell: Well it sounds like some of you have not managed to
download this so what I'm going to suggest is we leave this video to the
end. And that those of you have been unable to download it so far will
have a bit more time to try to get to it.

Amanda Hendrix: Okay. But in the meantime.

Man: Oh wait, excuse me, before you do that, tell us what the name of it
is on this video page.

Jane Jones: It's called Titan's North Polar Region.

Amanda Hendrix: So it's on the top row on the right.

Jane Jones: Top row, the right most of multimedia videos latest videos.
And if anybody needs the link we'll be happy to email it to you, to all
the various lists.

Karl Mitchell: Could you send out the link to the list now so that I
don't have to ask?

Amanda Hendrix: I can send it out.

Karl Mitchell: That will be great. Hopefully everybody will be able to
download by then. So if we could slip on to slide number 11, present
daily (unintelligible), sorry for all the pauses here. Obviously there's
a lot of animation here so it's not quite as simple as basic PowerPoint.

So I've been talking about the case for liquids. Whenever I present this
to an audience I get a different reaction. Sometimes they start to
become immediately convinced that these are liquids, other times they're
more skeptical.

So we decided that we had to make a stronger case, a watertight case if
you will. And so we brought together all the data that we could and
every argument that we could in order to make as strong a case as
possible.

Now again, it's very difficult to come up with a deductive smoking gun
argument in favor. Nearly every individual component of the argument has
a possible flaw.

However if you can build up enough arguments that make the alternative
seem less and less realistic, perhaps we can come up with a case that
everyone's happy with.

So if any of you read the major paper, I've got no idea if any of you
did, again it's not essential, we suggested that there was one
possibility which was a solid or gooey or potentially powdery organic
hydrocarbon or (nitrous) residue.

Next image please, and this, there were various lines of evidence that
we used to suggest it wasn't, in particular these drain feature here, so
this top image hopefully will pop into your screen labeled B at the top
right which we've interpreted as (playas) or empty lakes.

There was the low microwave reflectivity, but more recently with some of
these images we've been able to see features along the floor that vary
in darkness and we came up with a little thought experiment which was
that if you saw a channel leading into a lake and then you saw that that
channel existed on the lake floor bottom and continued through the lake.

If that lake was liquid filled, it should get darker, the channel floor
under the surface of the lake should get darker if it really is an
(unintelligible) channel so that the lake was now filled beyond that
level.

This is because you should be looking through progressively more and
more liquids because that lake would have had to, that channel would
have had to have gone downhill, so when the lake rose above it and
looking through more and more depth of liquid.

And so we measured the radar reflective, the radar brightness along this
channel here which is the third inset in I think on this present daily
(unintelligible) slide, and it's reversed, so from right to left of the
box on the top of the slide, it's from left to right on the graph, and
you'll see from normalized radar prospect the feeding reducers went down
further and further along these channels into the lake.

So that in itself was again very consistent with the liquid idea.
Perhaps you could come up with an argument that it always was changing
rain side distribution or something like that and progressively get
darker and darker as you went into the body of the lake.

But again another fairly strong piece of evidence in favor. Okay, next
slide please. Another exercise that we went through was to look at some
lakes from different angles. And again I've got a colleague in France
who specializes in this sort of multi-look modeling. And basically by
looking at something from different angles you get more of an idea of
how that something interacts with the incoming radiation, the incoming
light.

And he basically set up several different scenarios I've called them of
what the lakes consist of whether it was liquids, whether it was solids
whether it was some sort of grainy material., and used his model, put
these into his model as a hypothesis test for what these might be.

So random models, several times with different combinations of
materials, different depths of lakes, that sort of thing, in order to
try to account for the observation.

Now mostly everything was consistent with standing bodies of liquids.
Notice that there's time intervals between these observations, but
nearly every observation that we made of lakes, there was no evidence of
any kind of change in the contents however.

So by and large again consistent with liquid lakes, potential consistent
with solid, but they would have to be solid of vary scattering
properties for the radar, unusually varying, again something that would
be quite difficult to account for, changes in grain size distribution or
gravelly on the surface.

One lake in particular that we tend to refer rather dryly as Lake 20 I
believe it's been put forward for an official name, but this one shown
here in this modular modeling slide, number 20, number 12 I should say,
this showed some brightening in the bottom left hand, bottom left of the
lake as you observe it from here.

And my colleague (Phillipe) ran his model for this lake and focused on
it in particular and found that there was three possible explanations
that fit in with the observation.

One is that this was indeed a liquid filled lake and this liquid filled
lake, the level change by at least three meters. And so what you've got
is drainage from the first pass to the second pass. That's fine, but
unfortunately there are as ever with this sort of modeling alternative
explanations.

Another is that this is just a simple lake but with a slope in the lake
bed and due to the different angles that we are observing this lake
from. The first of these is 31 degrees from horizontal, the second is
sixteen degrees from horizontal. So you're looking at a different
(raising), different observation angles.

But it simply is a trick of the light as it would be with optical
imagery, and that you're seeing through different levels of the liquid.

Man: Before in presentation mode the slide numbers don't show up on the
screen, so it would be helpful if you'd tell us what the title of the
particular, because you've got these slides with different images that
pop up and sometimes it doesn't match what you're saying.

Karl Mitchell: Okay. The slide name is multi-look modeling.

Man: Okay, thanks.

Karl Mitchell: Okay. So yes, the second potential explanation is that
this is a liquid with a slope in the lake bed, and thirdly that we could
still just about explain this using a solid surface. It was much more
difficult but we had to have a very, very specific configuration of the
material whose properties changed spatially over the surface.

But again it was still plausible. We can't actually come up with any
real material that would fit this, but we still thought we should
address that as a possibility. Again, still no smoking gun, but now I
think that the case had got to a level at which everyone I speak to at
least in the community is happy with this interpretation that people are
(unintelligible).

We're a very skeptical community sometimes so it takes a lot of work to
get these ideas through.

Okay, the next slide is called origin of depressions one. I mentioned
earlier that we had the idea that some of these features might be
cryovolcanic and certainly morphologically some of these circular
depressions and particularly the nested ones, but many of the lakes do
look like volcanic calderas and I'm thinking Kilauea, crater lakes as
being perhaps the (unintelligible) of North America.

The problem that they're difficult to account for considering the number
of lakes and the fact that most of the lakes are not this kind of very
neat steep nested structures. And so if only a few of them have
cryovolcanic features, well why would any of them be cryovolcanic
features?

That was the big question that came up. Next time step please, this is
crater lake origin again, this is the same sort of size as the previous
slide and it shows how there are some striking similarities.

Again I'm afraid I didn't manage do find a radar image of crater lake
origin, but you can probably make out the similarities there. And the
next time step is an example of some lakes that we really don't think
are easily explained cryovolcanic calderas, they're fairly large
structures they may have circular aspects but there's islands connect
this, channels leading into them, volcanic calderas don't normally get
channels leading into them unless they are particularly unusual ones.

And it would be difficult to account for the huge abundance of these
lakes at the North Pole, you'd need some, if they were all calderas of
some sort you'd need some incredible hot spots under the north polar
cap.

And we haven't really come up with an explanation as to why this might
happen to Titan. There are ideas as to why it happened on one hemisphere
at least for (unintelligible), but no one's come up with a decent
geological explanation for large volcanisms on something.

Next slide, origin of depressions two, so instead we've been looking at
this karst analog. Karst is a geological feature formed by the chemical
dissolution of soluble substrate and normally limestone or something
like that on the earth.

They are generally formed, well the advantage of this process is you
don't need a second geologic process to form it, the existence of the
lakes themselves explains the depressions, all you need is standing
bodies of liquid in any old depression for any period of time and they
will start dissolving into the substrate.

The problem is, is the, at least for most of the time we've been
thinking of the substrate being (waterized), and if you put liquid
methane on (waterized) at these temperatures, you don't get the
solution.

However, the atmosphere model also been suggested that other stuff, no
doubt as suggested, many of these products would be something that
people in the petroleum industry would be quite familiar with, benzene
being one of the, acetylene, things that are quite often highly
flammable on the earth, they form fairly inert on Titan (unintelligible)
but behave somewhat like (unintelligible) rock on the earth.

But are they soluble at least to some extent or another, sometimes
sticky, sometimes not, and they could certainly or at least some of them
explain dissolution chemistry.

So maybe we're in a situation where this entire polar region, excuse me
for a second, where this entire polar region is covered in some layer of
snow like, I guess snow is as good as any, again there's analogs where
the Artic and the Antarctic on the earth.

So this idea was something that (unintelligible) sprung on us, a few
colleagues suggested it to begin with and then we went with it. The
great thing is that you can explain almost every feature in this north
polar region.

Nothing we have is inconsistent with karst. There are some problems.
Karst lakes are generally smaller on the earth, lots smaller, of course
there could be lots and lots more karst lakes on this image.

We're seeing down to at best a few hundreds of meters resolution, there
may be millions of these little things down in tens of meters
resolution, we don't know for sure until we can get a land rover or a
separate spacecraft.

But certainly these are the large for karst lakes on the earth. If you
could do the next time step please, why is not working for me. And the
next time stamp after that, this is an example of thermokarst in Canada
I believe.

Thermokarst is a bit like cast, the lake basically melts down into the
substrate and it can spread very caldera like because at times. What
we're looking at thermokarst largely because the scale of thermokarst in
the earth is also quite large, it's often more comparable with these
features on Titan.

Why we get thermokarst scale features rather than karst scale features
is a matter of some debate. Potentially you've got a much longer time
scale involved with these process I'm talking about, you don't have
quite the biological activity that you do on the earth.

Erosion rates are probably much lower, so these features may have a lot
longer to form and so potentially they could get a lot larger.

And this final slide here just shows some of the...

Man: Is the, could you define what you mean by thermokarst?

Karl Mitchell: Thermokarst is what happens when you've got a body of
liquid on the surface of the earth specifically and incoming solar
radiation and that incoming solar radiation heats up the liquids to such
an extent at which the body of liquid itself melts the substrate.

So where you have this on the earth is, it's quite common in Alaska and
Canada where you've got permafrost regions so you've got soil that's
saturated with water ice.

And so you get a liquid raining out into the surface, and rather than
immediately freezing because it's got some components so it can be
heated by the sun, it stays warmer than the surrounding materials and
then starts to melt into the substrate.

They're quite unusual features, they're extremely well drained at times,
and sometimes they can just vanish almost overnight. You can get lakes
that are many hundreds of kilometers, hundred meters across, but for
some reason something just pops in them.

And you get a little whirlpool forming and they drain out somewhere
else, the sea is generally in coastal areas. But if you ever, if you've
access to Google maps at some point look at the west coast of Alaska
you'll see loads of it.

Now we don't think this can happen on Titan, there's just not enough
solar radiation, meaning if there wasn't enough solar of radiation it
probably mostly from the (unintelligible) of the atmosphere.

But and so karst is a much more realistic process and we can rule out
this dissolution chemistry.

But morphologically speaking they seem to actually based on appearance
similar to karst in Alaska, so we've been looking at quite a lot of
these Google maps and Google earth images of Alaska maybe at some point
we'll get a (unintelligible).

So the last of the images on the origins of depression two slide, is
Florida, central Florida, which shows some fairly large karst lakes. I
said in general they're much smaller than the ones on Titan.

The largest of these ones that you see here in Florida are actually
comparable with some of the fairly small ones on Titan. And you see that
some of the are very circular, there's one slightly above right center
of the image that is very circular and could easily be mistaken as a
volcanic caldera if you look if you decided to interpret it on its own.

The other thing that's quite striking about this image is that you'll
see what looks like a ridge from top to bottom of the image and to the
west of that ridge, the lakes in general seem to be smaller than the
lakes right of that image, well that's because they're different
geological surface units that have slightly different dissolution
properties.

And so perhaps this is an explanation for the clustering of the
different features that we're seeing on the planet in just the surface
of geology variations modulate the appearance of the lakes as they
dissolve into the substrate.

Next slide please, called consequences of karst. So as I said it
requires a methane soluble substrate to explain that. And we have to
speculate that chemistry.

We do have spectroscopic instruments in orbit around Titan, those
spectroscopic instruments are very good but unfortunately Titan's
atmosphere is very opaque and so we really don't get accurate specter of
surface features.

Certainly not accurate enough in order to determine what the chemical
composition might be which is what you would normally get for planets
with no atmosphere. And so we need to use a combination of models and
inference in order to get as educated a guess of what the surface
materials might be, and also you need to observe what the chemistry is
in the atmosphere.

And we've certainly seen chemicals like benzene in the atmosphere.
Here's a list of substances that were once at least thought to be, this
was a long time ago, this slide was put together in 1987, so this is a
short one.

One thought has been materials that could exist has been dissolved in
the oceans of Titan. I don't expect you to go through the numbers all
that much except for how long could the column of (unintelligible) be
resolved.

And that the figure in parenthesis here under resolved is part familiar.
And anything that can be dissolved in a liquid methane or ethane body to
the extent of maybe ten parts per million or greater is something that
may well be an explanation for karst like properties of the surface.

So clearly water is well below one, so it's not even on this chart. But
certainly as separately plausible and we could have (unintelligible) on
the surface of Titan in the far right column, someone might suggest that
you could have about (86) meters worth of (unintelligible) globally if
it didn't react with (unintelligible), it probably does react with
(unintelligible) of materials.

And so I mean that could be an explanation. There are others like
benzene, propane, again things that people in the oil industry would be
very familiar with that would also dissolve down to these levels also
for these hundred meter scale depressions by withstanding bodies of
liquids for maybe tens, hundreds of thousands of years.

So we have some candidates with out a future mission we'll probably be
unlikely to resolve those, we really need a land rover, land somewhere
up near the poles or some sort of balloon mission in order to really get
at these, as we get at these properties of the surface.

If this is therefore karst, and if the depths of these lakes which we
have in places mentioned a few hundred meters is indicative of a fitness
of a non-waterized soluble layer, then we actually have an extensive and
thick polar cap.

Now this isn't like the polar cap on the Earth in that it's not
something that will face changing into liquid or melt. The liquids and
the (unintelligible) in polar regions are actually quite different
chemistries.

Nonetheless, it's something that is again a striking analog with the
earth. If there is such a polar cap it really will have a
(unintelligible) thermal activity compared with waterized, and possibly
you get some sort of build up of (teaching) leading to more active
subsurface chemistry.

A colleague of mine, (Jeff Cargo) used the word dunes to explain some of
those materials that could become fairly mobile as liquids and solids.

And so you can see (unintelligible) changing out things on here and this
is really vast variety of speculation that can go on here. But the point
here is we really cannot know anything like what the real variety would
be.

It's likely that the complexity will be beyond our ability to be able to
grasp them from (unintelligible) studies, this is one of the reasons
that we're hoping sometime in the future that we may be able to go back
to Titan and study it in more detail.

The complexity is really only comparable with processes on the earth, no
other planet has quite this active a (unintelligible) of chemistry.

Okay, next slide please, drainage this one's called. I've shown bits of
this slide before and I mentioned that karst is associated with a well
drained surface.

On the earth when you find karst you also tend to find these things
called sinkholes which are lake like and you also find caves. Earlier we
were talking about how you had regions with small lakes, regions with
large lakes.

There's no real evidence of surface interconnectivity, so no channels
linking the small lake region with large lake region. And so we'd expect
that they, if you had equal rainfall throughout the entire polar region
there would have to be transport from one to the other.

So this must be in the subsurface. Again, supporting evidence that this
is some sort of karst like process, again this is this is the
(unintelligible) where you can see through the liquids.

Let's skip that and go onto the third image on this one, this is a tall,
long thin image, again this is showing more evidence of drainage here.
There are some of these river-like features near the top here, there's a
river connecting to an outlet into a sea-like area.

And also there's these drained lakes around here, this is all very
familiar to those people that have studied karst on the earth, and we
never really thought we'd be consulting people that studied terrestrial
karsts, this is something that no one really predicts at the time.

It was a most surprise and now chatting with terrestrial scientists and
bringing in other areas of the community which is fun to be able to do
for (unintelligible) talk about the surface of the planets, talk about
impact craters and volcanoes and it's good to have some sort of cross
fertilization with different academic communities.

So subsurface flow on quite a large scale seems inevitable. This is
something we're only getting into modeling now. We hope that we'll be
able to come up with ideas about what the lake, the flow are plausible
and maybe the existence of these large lakes we can infer something
about the rates of flow and then infer something about what the
subsurface materials might be.

But again study for the future. I mentioned earlier that we had a bit of
a look at the south pole, so let's go on to the next slide, there's not
many left now. We predicted after seeing a few flybys of the north pole
that there would be south polar lakes.

I assessed the imaging instruments, I'd actually observed a dark
(unintelligible) images. The initial suggestion that there might be a
lake on Titan from Cassini (unintelligible) comes to mind there, like
the one in Ontario (unintelligible).

And we now feel fairly comfortable to support her interpretation, again
this is a dark blob against a pale background so at the time it was
fairly speculative.

But it turns out to most likely have been right. So this slide here,
number 18, south pole predictions and first observations, shows our
first flyby of the southern polar regions.

And this little insert in here showing the, using the same sort of color
scale as we used in the north pole and you'll see that there are a few
tiny little lakes. Again we didn't get too close to the pole with this
one, I think we got about 72 degrees north.

So we didn't expect many lakes on this flyby and we found just a few,
so.

Amanda Hendrix: And is Ontario Lacus on here?

Karl Mitchell: No it's not. We're going to image that at some point in
the future, I just can't remember when, it's within the next year I
believe.

(Ken): Where would it be located on this map if it would be there, this
is (Ken) from (unintelligible).

Karl Mitchell: I really can't tell you, I'm sorry about that. It's
somewhere around 75 degrees south but I can't remember the longitude.

Amanda Hendrix: The longitude is about 180 west.

Karl Mitchell: One eighty west, okay.

Amanda Hendrix: Yeah, 180, 190.

Karl Mitchell: Okay, there you go, near the bottom left of this image.

Ken Kremer: What is the size of these particular lakes compared to
Ontario Lacus, are they much smaller, about the same?

Karl Mitchell: Much smaller. Ontario Lacus is more of a large sea-like
body inside of the northern hemisphere, but larger than most of the
lakes. So I'll be interested to see what the morphology's like, whether
it's more consistent with the lakes or the seas or whether it's some
sort of (unintelligible) when we actually see Ontario Lacus finally.

The other thing is that there's 180 degrees out in terms of seas in the
southern hemisphere. So when we see here there may well be differences
in how filled the lakes are compared to the northern hemisphere.

Some people suggested they may be more filled, some people suggest they
may be less filled. You can't really get that much from this first
flyby, but if we map out the southern hemisphere and find out there are
differences, then that will hopefully tell us something more about the
climate.

Ken Kremer: Well this is summer I guess right, because in the north it's
winter right now, right?

Karl Mitchell: In the north I think it's approaching spring, so it's the
end of the summer. Maybe someone else on the teleconference can confirm
that but yeah, we're hoping that Cassini will last long enough to get us
well into the spring.

And so there's some chance that we may well see any changes due to
seasonality, maybe just at the north pole. But to begin with contrast of
the south pole will probably tell us quite a bit more.

Ken Kremer: My question is basically where is, what's the temperature
difference between the north and the south pole right now?

Karl Mitchell: It's not all that great. It's of the order of 1 Celsius
we'll say.

Ken Kremer: And that's all?

Karl Mitchell: Maybe two. Yeah, well it's like the whole planet's
blanketed. So it remains fairly constant, it's kind of like a tropical
climate in some ways, it seems counter intuitive for somewhere that's so
cold.

But it's got a very thick atmosphere, it's like having a major
greenhouse effect going on. So the temperature variability isn't that
great. However over a daily time period you get some variability as
well.

I think that, I thought they suggested four or five Kelvin might be the
temperature extreme at the poles, either way, so well within the
(unintelligible) of Kelvin, so pretty cold.

But those slight changes can make a big difference climatically. I mean
just (unintelligible), so.

Ken Kremer: But it's not like it's dramatically colder and there would
be a lake now as opposed to when it got warmer and it would all
evaporate.

Karl Mitchell: Well we don't know that for sure. The lakes are probably
constantly evaporating to some extent just like water is on the earth.
They need to be replenished by rainfall.

And so if you've got a season in which rainfall doesn't occur as much,
just use a tiny difference in temperature variability, then yes you
would expect to see lakes going down.

Also if you've got subsurface drainage, the rate of which you would need
to replenish them would be higher. So there's a fair chance we will see
seasonal variability if we have enough observations of the last mission.

But again it is still early days even though it's been imaging since
1994, not 1994, 2004.

Ken Kremer: And there are more passes of the south pole coming up, is
that right?

Karl Mitchell: Yeah, this is just our first one. We're not going to have
as many as the north pole, in the extended mission I think we've got
three...

Amanda Hendrix: Is this north or south Karl?

Ken Kremer: I'm asking about the south.

Amanda Hendrix: Yes. Most of the ones in the south and then only one
more in the north late in extended mission and (unintelligible).

Karl Mitchell: And of course we are hoping for Cassini to go on
indefinitely effectively, I mean....

Ken Kremer: The problem with going on indefinitely, actually I spoke
with Jonathan Lunine about this, you don't have enough fuel, right?
Beyond about seven years.

Karl Mitchell: You can conserve fuel by using a slightly more
conservative campaign if necessary. It depends on the pros and cons, I
know the imaging instruments can suffer by being in space for too long
so you've got more net cosmic radiation bombardment and that's what can
be more likely to go wrong.

The radar doesn't suffer too much from that, but I think most people
want the mission to last for a very long time because seasonal
variability would be an amazing thing to find and there are other
potential benefits of keeping it going for as long as possible.

But I've heard people suggest 2012 or even longer as how long this space
probe could last for, someone once suggested (unintelligible) of 2016 I
believe. I don't know whether this is going to be the strategy that we
go for in the end.

It's all very much you have to respond to circumstances, but we're
optimistic that we'll get a lot more images out of that.

Ken Kremer: Thank you.

Karl Mitchell: Okay, next slide. So I'll come back to this slide that we
showed at the beginning which was an attempt to show all the evidence of
the different (unintelligible) type processes and type of hydrocarbon
cycle.

And so we've come full circle to a certain extent, now we're trying to
understand the relative contributions of all these different processes
and see how they all mesh together.

This is very much analogous to the understanding of the water cycle on
the earth, often found in science lessons at schools. But it is
incredibly important for life on the Earth, and it's also important for
how Titan as a body works.

If we can understand the components of this hydrocarbon cycle on Titan,
we've very much in understanding how the planet lives and breathes. And
so these standing bodies of liquid form an, fill an important role in
this process.

They balance the amounts of methane in the atmosphere. If methane in the
atmosphere goes down you get a high rate of evaporation,
(unintelligible) when the atmosphere goes up you get a low rate of
evaporation and you get precipitation.

And so that's critical to this whole system. The inputs to the system,
the cryovolcanism is something we still don't really understand all that
well. With sink features that are indicative of cryovolcanic activity
and we've got observations planned that will test some future ideas.

We certainly haven't seen anything that suggests that there is
cryovolcanism ongoing at the moment although potentially it could be.

And so we're very much trying to understand in the future, trying to see
if we can come up with anything that suggests that there's something
that's going on and understand the nature of the cryovolcanic process.

And we're going to be doing some work on that at JPL as well, the other
half of my research. But understanding this all as a living breathing
system, much like we try to understand how the earth works, is very much
a goal of scientists in the next few years, now that we've managed to
get some idea of the surface variability of Titan.

Okay, on to the next slide. In order to get a handle on that we're going
to have to understand the physical properties and the chemical
properties of all of these materials.

Most of the non-waterized components that could be on Titan are well
understood on the earth, under earthlike conditions, but at these low
temperatures that we observe on Titan, there have been very little lab
work done.

And so JPL has started up a new cryoices lab. Our groups around the
country have, and abroad as well, particularly my colleagues in France
have been coming up with various experiments to understand not only how
these various materials interact, how methane dissolves through solids
for instance, but also how they interact with the radiation relative to
the Cassini instruments.

So there will be different things to look at on the radar. Some of this
obviously had been done before the mission, but it's amazing how many
things come up mid mission that we go why didn't we ever ask that
question before?

And so a lot of the work that's going on at Cassini now supporting
Cassini is somewhat behind the scenes of the (unintelligible) we've got
great people doing various experiments.

As I said at JPL we've got this cryoices material we're synthesizing
ices of different sorts, and we're using ice in the very general sense.
Now this is a solid that's a liquid or a gas under conditions on the
earth, so various of these hydrocarbons are called ices.

We're measuring the mechanical properties, how they respond to strain,
things that might be in a liquid state, we're measuring some of their
viscous properties, how they flow.

We're looking at how methane would interact with different solids, if
you put a drop on the surface, what would it do? This isn't always
something that's obvious and can't always be modeled very easily until
we've done some basic experiments.

So some of these things, a lot of these things are ongoing at the
moment, and I'm sure lots of people would be very happy to talk about
these in depth, but I'm not going to spend much more about this.

Next slide, conclusion. I won't spend too much time on this, I'm getting
to the end now. Cassini RADAR has revealed a world that has an
incredibly rich landscape. It's got lakes, it's got things that look
like volcanoes, and a lot of these are active today which makes it quite
unique in the solar system.

It's more planet like than many of the planets, even though it's just a
moon of Saturn, it's a big moon and there's a lot going on. Not a lot of
planets that we've seen seem to have as developed an environment system,
a complex interaction that we have on Titan, (unintelligible).

And so we're considering Titan to be a remarkable place to study
processes as a whole without just thinking of them as purely earth
terrestrial processes. We get a glimpse of how lakes behave with
different materials under different conditions, and whether the rules
that applies to the earth also apply to other planets.

We think that these lakes, and the subject of this talk are liquid,
primarily methane, ethane and lesser quantities of dissolved nitrogen.
We cannot say that 100% for sure but every piece of evidence, every
little test we come up with supports this idea that they are liquid.

First time we found standing bodies of liquids on any, other than
volcanic liquids, Io is an exception, and Triton as well, volcanic
liquids on any body other than the earth.

So this is a major discovery. We, one thing we started to do more
recently is try to estimate a depth of some of these lakes, because the
lakes are transparent we can get some indication we may also be able to
get some indication of (unintelligible).

There are various techniques to try to estimate the surface of the
solids, but the liquids are a bit more tricky. So hopefully we'll be
able to get a very good indication of the total lake content of Titan.

I know that (Ralph Laurent) has done some preliminary estimates of this
that are a lot more liquid methane on Titan compared to some
(unintelligible) we've been able to observe than there are terrestrial
oil reserves frankly, to get some idea of scale.

But there's so much more work to be done, so many unknowns, so we're
hoping that in some point in the future we'll be able to go back to
Titan. I think that's it apart from the movie.

I hope that all of you have been able to download the movie by now, if
not we'll send you the links and maybe you can look at it another time.
So if you could go to the movie, those of you that have access to it, on
this PowerPoint slide I'm looking at slide number ten.

And to start it up you will have to click on it, so if you start it up
now, I'll take you through it. Hold on a second, I'm just going ask you
to pause it, for some reason it's not showing for me.

Woman: Is Amanda still on?

Amanda Hendrix: Yeah I'm here.

Woman: Amanda when I went to the multimedia latest video page, the one
we told people about, the one on the top row, the fourth one, that's
actually not the one that's linked to the Charm Telecom. It's the radar
shows evidence of seas, which is on the third row down on the latest
video page.

Amanda Hendrix: Okay, thanks.

Woman: I had already sent out an announcement listing my Saturn
observation campaign people and then I figured I made a boo boo.

Amanda Hendrix: Okay, thanks for point that out though.

Karl Mitchell: Okay, I'm going to start the video in a few seconds.

Amanda Hendrix: Okay, hang on real quick Karl, does everybody have it
up? So anybody who has a web browser, can go to the Cassini website,
click on multimedia and from there go to videos.

And then the third row down, there's a whole bunch of videos, in fact a
whole bunch of these are brand new, but the one that is linked to the
Charm telecon is called radar shows evidence of seas.

There's a couple of other Titan ones, that's where I got confused and
one of them has that beautiful mosaic, the Titan north polar region, so,
and the page, the Charm telecon page is in the process of being updated
but (Kirk) our webmaster can't get a hold of the Raytheon contractors
who will actually make it happen.

So he's trying to be on the phone with those people making it updated.
He had already noticed it was wrong but couldn't get a hold of the right
person.

Okay, maybe we can go ahead and start now?

Karl Mitchell: Okay, when I say now if everybody could start
simultaneously right from the beginning hopefully I can give you the
guided tour aspects of it. So three, two, one, now.

Okay what you're seeing here is a rendering of the Cassini orbiter
approaching Titan. The images we used are from the optical instruments
so they're much lower resolution.

Dark around the equator that you're passing here are actually the sand
dunes of Titan as they are referred to, so solid material. Titan, we're
seeing the orbit of the flyby no less than about 1000 kilometers
altitude above the planet.

So it gets fairly close but not as close as a dedicated orbit would do
around the planet. So you're seeing the Cassini orbiter slowly panning,
looking at the surface.

Now we're going to start showing some of the radar images, here you go.
This is some of this lake region here, we're actually going to cross
some of the sea like features.

So this is along the T25 swath, this is the entire panorama, now we're
going to start at the top left, and this area of small irregular sized
lakes here you'll notice they are depressions. Unfortunately the
illumination's slightly different for the different images.

But you can make out some of the depressions, they're clearly liquid
filled, channels of various sorts, varying morphology. The, how dark the
blue is gives some indication of how deep the lake is. There are various
structures on here that you see that look like depressions but are not
filled with (inert) materials so again these are the like lakes.

This is that big, on the bottom left here, we're flying past the basin
like feature that we said may or may not be liquid, various channels
coming to this, and I just hope everyone's on the same part of this as I
am.

Can begin to, mostly it speaks for itself to tell you the truth. I've
gone over quite a lot of these before. Various islands in some of the
lakes, again the morphology changes as you go across the scene and it
would suggest a large amount of geologic variability in the subsurface
features.

This is now going to take a right angle here and start going in a
different direction. This is a fairly low latitude region here, this is
about 70 to 75 degrees north range, and now we're going to swing up and
head towards about 80 degrees of a different one of the radar swaths.

You're just about to start seeing the dark river valley which we haven't
named yet but leads to very fjord like structures, you see lovely
crinkly river valleys and extended lakes that remind me a lot of Lake
Powell.

And now we're going to start panning out, zooming out and looking at
this massive area that we refer to as the Black Sea sometimes, very
informally.

And 100,000 square kilometers so larger than any of the Canadian Great
Lakes or North American Great Lakes. And there you have it.

I hope that that was possible for all of you to see but if not it will
work downloading from there later. I think I'll stop there.

Amanda Hendrix: Karl, I have a quick clarifying question, when you say
larger than the Great Lakes, you just mean literally square footage on
each one relative to the size of earth, those seas up at the top of
Titan are really very large, more like the Hudson Bay or something.

Karl Mitchell: Oh yeah, the surface area of Titan is a lot less than the
earth and I'm using absolute terms.

Those largest seas as we call them are many times the largest Canadian
Great Lakes, in fact they are comparable with the inland seas of Asia,
so the Black Sea, the Caspian Sea, maybe even slightly larger than those
in terms of percentage surface coverage.

Certainly a lot larger than the Great Lakes and the (Aural) Sea and
various other sea-like bodies on the earth.

Amanda Hendrix: Okay, just wanted to clarify, thanks.

Karl Mitchell: Okay, open to questions if anyone wants to ask.

Ken Kremer: Hi, this is Ken from New Jersey, I have a question about the
radar instrument itself. I'm going to be giving a talk about this, can
you tell me where on the spacecraft is this located, part of the
antenna, or below the antenna?

Karl Mitchell: It's the largest antenna on the spacecraft, it's the big
blue one that's sticking out the side. If you look at the movie, the
first time step of the movie you'll see the spacecraft there and it's
one of those two big blue ones facing forward and ones coming out to the
side.

I have to say that I'm not an expert on how the radar instrument works,
(unintelligible) a foreign national as we are not allowed to know how
the radar works. Export control data.

Ken Kremer: The radar, the instrument itself was built in Italy, is that
right?

Karl Mitchell: It's an Italian, yeah, it's a collaboration between the
Italian space agency and NASA. It was constructed largely by the
Italians in collaboration with NASA.

Ken Kremer: Okay.

Amanda Hendrix: And maybe Karl I could add two things to that. The high
gain antenna, the giant white dish at the top, if you were actually
looking at it with your eyes, you would see something you know in the
center that looks like a little parabola, which is the different radar
beams.

And then if you could see through the high gain antenna, there's a
series of I think, I want to say twelve or thirteen electronic bays that
have all the electronics and computers of the spacecraft, and the radar
bay takes up one whole bay of those.

So those little hexagon things that are right above the high gain
antenna, that's where all the electronics are, if that helps.

Ken Kremer: Under the high gain, not within, inside it.

Amanda Hendrix: There is a piece inside it, looks like a little, you
know looks like a little U shaped parabola, it's easily visible you know
if you were standing you know sort of looking at the spacecraft with you
eye, the high gain antenna is you know four meters in diameter and the
parabola's probably about a foot.

So it's easily visible and it's got a little U and it's broken up into
little pieces and it's easy to spot, and then all the electronics are
beneath the high gain antenna in one of the bays.

Ken Kremer: All right, thank you. You see I'm actually giving a talk to
an Italian club and that's why this is kind of important to me.

Amanda Hendrix: Yeah, the Italians built the high gain antenna and they
built several pieces of both the radar and the radio science experiments
on board Cassini.

Ken Kremer: Now did they design the radar, because I think Charles
Elachi is the principle investigator for the radar, is that right?

Karl Mitchell: Yes he is.

Ken Kremer: I'm curious who designed the radar, did he design it and it
was just built in Italy, or how did that work out?

Karl Mitchell: This is actually from before I joined the team and I have
to say I'm not really privy to the design, the Cassini radar, Amanda
probably knows more than I do.

Amanda Hendrix: You know I think, yeah, Amanda, I think it was designed
here at JPL. It's what's called a facility (unintelligible). So I think
the design came from the group of experts here at JPL, which Charles is
part of that group, he's also the lab director here and he's also the
principle investigator for the Cassini radar instrument.

So I think the design came from JPL and it was mostly built here.

Ken Kremer: Okay. But with Italy also, right?

Amanda Hendrix: Well the Italians built the high gain antenna, so....

Karl Mitchell: It's a critical component of the radar....

Ken Kremer: Right. So the radar then was actually built at JPL, got it.

Amanda Hendrix: Boy, gosh, I'm pretty sure.

Karl Mitchell: It's hard to say where one team, one group ends and the
other group begins sometimes.

Ken Kremer: Yeah, I've been trying to find this out, I've looked
extensively through all the Cassini literature and a little bit murky.

Karl Mitchell: When it comes to how the radar works and how it's all
designed because of the fact that radar potentially has military
applications, really often JPL doesn't, there's so much paperwork to go
through in order to get out that information that sometimes it's not
done as clearly as it could be.

Ken Kremer: I've got some science questions too now, the ethane
composition, what is the ethane methane ratio roughly.

Karl Mitchell: Unknown. Completely unknown. We, there are some models
that suggest that quite a lot of them have a methane in the atmosphere
would eventually become ethane, but there are a few constraints.

Originally, the Lunine (unintelligible) papers had suggested that the
oceans of liquid ethane based on various assumptions that clearly are
not true, they are suggesting that most of the surface would be
predominantly ethane liquid.

And so we're in a process of re-exploring that issue.

Ken Kremer: Okay. And the future radar passes, now you said there are
not going to be many at the poles, I guess they will be just distributed
throughout Titan or are they going to be equatorial or where will that
be?

Karl Mitchell: Well over the next year or so there's going to be two
more south polar passes I think, one more north polar pass, this is to
the radar one, because we share the observations of all these different
instruments, and so it's a matter of deciding which instruments need the
data most.

I'm trying to share between all of the different groups. There will be a
lot around obviously the lower latitudes. It's very much on a, the radar
does tend to fairly well out the flybys because whenever it's a
nighttime observation, whenever you're mostly looking at the dark side
the radar does tend to get the observation.

But we don't always get a lot of choice as to where the image because
you fly by when you can. But yeah, predominantly close to the equator
because of the (unintelligible) surface at lower latitudes.

Ken Kremer: Thank you.

Amanda Hendrix: Any other questions?

Woman: Amanda, I guess I just had one thing for the gentlemen who was
asking about the radar instrument, Chris Russell put together a set of
summary articles in Space Science Reviews, and that's an excellent
resource if you want to know the basics of any particular instrument.

So I'd take a look at that, it's Space Science Reviews and the editor
was Chris Russell and then look for the radar article.

Jane Jones: And I was also, this is Jane, I was also going to suggest if
you go to the Cassini website and go under the spacecraft orbiter
instruments.

Ken Kremer: I did that.

Jane Jones: There's a whole page on the radar instruments. Now the
difference between the radar instrument and the antenna is where I think
you're Italian connection comes in. So I'm actually looking for the
spacecraft antenna page.

Ken Kremer: yes, I looked there and that's what I'm saying, if there's
not a whole lot of detail there on who did what on where everything is
located.

Jane Jones: No, it tells about the instrument, it doesn't tell who did
what.

Ken Kremer: Yes, yes, exactly, it tells about the (unintelligible).

Jane Jones: We can't tell you that.

Ken Kremer: Okay, well that's fine...

Jane Jones: No, that was a joke.

Ken Kremer: No, it might be an ITAR issue, no I understand that that
could be an issue and I was just curious.

Trina Ray: No it's not ITAR issue, it's in the Space Science Reviews and
in fact I just found it, I'll just take 30 seconds here to tell you what
it is.

There are four subsystems for the radar instrument, the quickly let's
see, one of them, the RFES, which is the radio frequency electronic
subsystem was built by the Italians.

The second one, quickly Trina, built at ESS, the energy storage
subsystem was built at JPL, the high gain antenna was built by the
Italians, and that must mean there's one that I'm missing.

Ken Kremer: They built the low gain antenna too.

Trina Ray: They also, no I, who built the low gain antenna, I believe
that was built at JPL, but I'm not sure. And the DSS was built, the
digital subsystem was built at JPL.

So basically half and half for radar, half from the Italians and half
from JPL. And we all learned something today.

Ken Kremer: Thank you, no that's really helpful.

Karl Mitchell: The Cassini Huygens mission is actually a very good
example of the Americans and the Europeans working extremely well
together, obviously the (unintelligible) was predominantly European and
the (unintelligible) was predominantly American.

Ken Kremer: Is it possible to get your email in case I have any follow
up questions?

Karl Mitchell: Sure.

Ken Kremer: My name's Ken Kremer by the way, I'm a JPL Ambassador.

Karl Mitchell: Right, my email address is karl.l.mitchell@jpl.nasa.gov.

Ken Kremer: jpl.nasa.gov. All right I'll send you an email then.

Jane Jones: And anyone who has regular questions any time can always
send them to the email address that's on every single announcement of
these talks to charm_leads and we'll be happy to forward them in case
everybody didn't write down Karl's email address, we're happy to take
the questions and pass them on.

Ken Kremer: This is Trina?

Jane Jones: No, this is Jane.

Amanda Hendrix: Any other questions or anything right now?

Man: Cryovolcanism, I've wanted to ask about that.

Man: You say there was no evidence, did I hear that correctly?

Karl Mitchell: We have lots of evidence of cryovolcanism. We've got
surface features that look like cryovolcanic features, we have nothing
that is convincing evidence for active cryovolcanism and some of the
features that we've interpreted as cryovolcanic may be open to different
interpretation.

Man: Right, there was one about a year ago that I thought was pretty
convincing at that time.

Karl Mitchell: Yes, (ganishin macular) is possibly the one you're
thinking of, looked like a massive dome. I was a co-author on that
paper, yeah I mean I still think it's cryovolcanic but it's certainly an
unusual feature that can't be explained simply by direct dialogue with
features from the earth.

So I hope, well we've actually got a second observation of that but it
hasn't been thoroughly released yet, and hopefully we're going to get
stereo (unintelligible) eventually so that we can construct a 3-D
terrain model which will allow us to test even more ideas.

Man: Okay, thank you.

Karl Mitchell: Before everyone goes, if you are interested in looking at
this further I should point out the photo journal at jpl.nasa.gov
website which has all of the image releases that we've put together from
the Cassini RADAR instrument along with every other planetary instrument
that's been run.

It's well worth checking out because there's a lot on there and they've
all got detailed captions explaining our interpretations at least at the
time that we did the image release.

The movie's on there as well.

Woman: Okay, any more questions?

Ken Kremer: Well let me ask one more question if no one else has a
question then. The large lakes are on one side of the moon, is there any
reason for that?

Karl Mitchell: There is probably a reason for it, it doesn't look like
it's just a, it looks like it's a real geologic thing, I've looked into
the very striking contrast between one (hemispheric color) and the other
hemisphere.

The probable explanation is either due to topography or drainage or a
combination of them both. The very lake like areas I would think that a
good explanation, it might not be the explanation is that they are
higher and better drained than the sea area.

And so the liquids drain into those sea areas, and there's certainly a
lot more area of the seas that we can see at the moment at least, on one
hemisphere than the other which would kind of suggest that there's some
liquid transport from one to the other.

Ken Kremer: Okay, very good, thank you.

Karl Mitchell: That's speculation by the way.

Ken Kremer: Sure, sure sure.

Karl Mitchell: A lot of this is speculation, I mean you've got data
that's been 150 meter resolution, there's only so much you can do, I
mean if you think back to the Viking orbiter days and Mariner days,
their image resolution was actually slightly superior to what we are
looking at now (unintelligible).

So this is early days for time study.

Man: Do you have any kind of future missions, would you like prefer a
lander or a balloon mission?

Karl Mitchell: I would be very happy for us to go to Titan in any
capacity in a dedicated mission. I, as someone who deals mostly with
remote sensing data, I'm more interested in the balloon mission, because
a balloon mission allows us to get spectral to view the white area of
the surface, we could go from equator to pole let's say and see a lot of
different unit types.

That is a purely personal prejudice, so I know there's lots of people
who have very good arguments for suggesting a lander mission.

So I don't know, and a dedicated orbiter as well would get us lots of
data when we cross the uplink to the earth.

So almost any mission that's going to go back to Titan will probably
have to have an orbiter and a lander or balloon or lander and balloon
component, and it will probably involve the Europeans as well if it's a
large scale mission.

Greg Cermak: This is Greg Cermak in Portland Oregon. One of the slide
you had you had listed quite a few organic compounds and I know there's
been a lot of interest in these compounds called (solenes) which are
organic intermediates.

Has any of your work touched upon that, I know it's a little outside of
what you're doing in terms of the cycle, the weather cycles and stuff
like that, but do they have any evidence of that through spectroscopy or
anything else?

Karl Mitchell: (Solenes) are a tricky one. There are lots of features
that are consistent with (solenes). As to whether you can tell 100% for
sure they are (solenes) as opposed to other organics, I am not sure
we've got very strong evidence on the surface.

Certainly the models would support it. The preferred series of the
(unintelligible) the equatorial dark fine grain materials that point no
doubt are that they are very (unintelligible) (solenes).

As for their role in the lake processes, I have very little idea. Again
we've got this huge range of materials that we're having to look through
the physical makeup of them how they interact with liquids in order to
understand these lakes, you have to be working on that very steadily and
surely over the next few years.

Greg Cermak: Could you elaborate a little bit further on what you said
with regard to the dunes at all?

Karl Mitchell: Again, this isn't really my area, I think there was
another dunes presentation a few months ago that may have to talked to
that, is that correct Amanda?

Amanda Hendrix: (Ralph) did a dunes presentation I think back in March,
or maybe....

Karl Mitchell: yeah, that would be fairly up to date and I think I
prefer to refer you to that because again I don't really know all that
much about the dunes.

Greg Cermak: That's fine, I was just curious. All right, thank you.

Amanda Hendrix: Any other questions? Okay, well I'd like to thank
everybody for calling in and participating and thank especially our
speaker Karl Mitchell for an excellent talk, and it was really
interesting and informative.

Karl Mitchell: Thank you.

Amanda Hendrix: Did somebody say something?

Karl Mitchell: I just said thank you.

Amanda Hendrix: Okay, now as a reminder for everybody we will not be
having a Charm telecom next month in December but we will have one at
the end of January, the last Tuesday in January and so stay tuned for an
email on that topic.

So thanks everybody and we'll talk to you in a couple months then.

Woman: Thanks Amanda, thanks Karl, it was great.

Man: Thanks for organizing these, they're very nice.

Man: Thank you.

END