Cassini Spacecraft Images Seas on Saturn's Moon Titan

[telfrow]

<i>Instruments on NASA's Cassini spacecraft have found evidence for seas, likely filled with liquid methane or ethane, in the high northern latitudes of Saturn's moon Titan. One such feature is larger than any of the Great Lakes of North America and is about the same size as several seas on Earth.<br /><br />Cassini's radar instrument imaged several very dark features near Titan's north pole. Much larger than similar features seen before on Titan, the largest dark feature measures at least 100,000 square kilometers (39,000 square miles). Since the radar has caught only a portion of each of these features, only their minimum size is known. Titan is the second largest moon in the solar system and is about 50 percent larger than Earth's moon. <br /><br />"We've long hypothesized about oceans on Titan and now with multiple instruments we have a first indication of seas that dwarf the lakes seen previously," said Dr. Jonathan Lunine, Cassini interdisciplinary scientist at the University of Arizona, Tucson.</i><br /><br />Link<br /> <div class="Discussion_UserSignature"> <strong><font color="#3366ff">Made weak by time and fate, but strong in will to strive, to seek, to find and not to yeild.</font> - <font color="#3366ff"><em>Tennyson</em></font></strong> </div>

 

[JonClarke]

That's very impressive. Proportionally a body of liquid that size on Titan is equivalent to one twice the area of the the Mediterranean on Earth. That is quite a sizeable body of liquid.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[3488]

Hi there.<br /><br />It is & it will be interesting to see if the shape & size of Titan's hydrocarbon lakes change shape & size as northern Spring Equinox arrives on Titan in August 2009.<br /><br />Note that the northern Spring Equinox arrives on Saturn four months later in December 2009. Titan's orbit is slightly inclined hence the four month difference!!<br /><br />Thanks telfrow for posting this thread.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[dragon04]

All that yummy potential propellant... Once confirmed, this makes Titan a future destination, I'd think.<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[kewell_]

Great! Now where is stevehw33??

 

[rhm3]

Assuming they are still liquid (probably are), this is a very exciting discovery. <br /><br />I wonder if there are waves on these seas? Previous radar images showed some mighty impressive dunes, indicative of surface wind. Perhaps Cassini could look for signs of that closer to where the seas are.<br /><br />Imagine a future rover landing right along the shore of one of these things...I have hope that Cassini won't be the last spacecraft to Titan (or Enceladus) in our lifetimes after reading this: <br /><br />http://spaceurope.blogspot.com/2007/03/fly-me-to-moons-athena-coustenis-and.html

 

[CalliArcale]

It's been hinted by planetary scientists involved with this effort that such a thing would happen; the theories to explain the formation of such "lakes" generally predict that such bodies would be seasonal. So if the lakes move south, it would be a very strong bit of evidence in favor. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[MeteorWayne]

I'd say until there is some sesonal history, it would be premature to judge that.<br /><br />Perhaps "sea level" is a combination of gravity and the gas to liquid and liquid to gas conversions at the local temperature with the local mix of gases....and liquids... <img src="/images/icons/smile.gif" /><br /><br />It might turn out to be fairly smooth (on long baselines) and still seasonal.<br /><br />Just suck up all the data, because it will be a long time till a comparable spacecraft will be there. Plenty (too much) time to analyze <img src="/images/icons/frown.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[JonClarke]

It would have thought that liquid bodies of this magntiude are too large to be seasonal. But the latent heat required to eavporate methane is much less than that of water, so I could be wrong.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[3488]

I have looked, but is there further news about Ontario Lacus near Titan's South Pole. This will prove that Titans lakes can at least survive in part the Titanian Summer!! <br /><br />I agree Jon, I think that large lake is too big to disappear in the Titan Summer. <br /><br />Another unknown is how deep? For instance, Lake Superior in the Graet Lakes, is considerably larger in surface area than Lake Baikal in Russia. But Lake Baikal is very much deeper & holds more water, therefore more energy would be required to dry it out!!! I assume the same would be true of Titan's lakes???? <br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[silylene old]

<font color="yellow">Another unknown is how deep? For instance, Lake Superior in the Graet Lakes, is considerably larger in surface area than Lake Baikal in Russia. But Lake Baikal is very much deeper & holds more water, therefore more energy would be required to dry it out!!! I assume the same would be true of Titan's lakes???? </font><br /><br />Not exactly!<br /><br />You need to consider the heat of vaporization, which is the energy required to cause the phase change of a liquid to a gas. At 1 atm pressure, the heat of vaporizations for water, methane and ethane are:<br />water....2260 kJ/kg<br />CH4........510 kJ/kg<br />C2H6......489 kJ/kg<br /><br />(Ignoring the small correction due to differening atmospheric pressure on Earth and Titan)<br /><br />It basically takes ~4x more energy to evaporate water compared to methane or ethane. So basically, until a lake on Titan is 4x larger in volume, the energy required to evaporate it would be less than a comparable lake on Earth. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[centsworth_II]

In addition to precipitation, some lakes on Titan could be spring-fed which <br />could cloud the seasonal picture. I remember that it was speculated that <br />some short channels in the Hugens images could be the result of springs. <div class="Discussion_UserSignature"> </div>

 

[JonClarke]

Depth estimates will be critical to determine what the volume of the lakes are and thus how likely they are to evaporate over a season.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[vandivx]

<font color="yellow">I have hope that Cassini won't be the last spacecraft to Titan (or Enceladus) in our lifetimes after reading this:<br /><br />http://spaceurope.blogspot.com/2007/03/fly-me-to-moons-athena-coustenis-and.html</font>color=yellow><br /><br />I should still be around in 2020-5 but I am damned if I care to wait that long, I'd rather spend the money now on booze, gambling and women and whatever than wait that long, its nice to see what's up there but not when it should take that long, bletch<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[silylene old]

<font color="yellow">You need to consider the heat of vaporization, which is the energy required to cause the phase change of a liquid to a gas. At 1 atm pressure, the heat of vaporizations for water, methane and ethane are: <br />water....2260 kJ/kg <br />CH4........510 kJ/kg <br />C2H6......489 kJ/kg <br /><br />(Ignoring the small correction due to differening atmospheric pressure on Earth and Titan) <br /><br />It basically takes ~4x more energy to evaporate water compared to methane or ethane. So basically, until a lake on Titan is 4x larger in volume, the energy required to evaporate it would be less than a comparable lake on Earth. </font><br /><br />I forgot to factor in the densities of the respective liquids.<br />The density of CH4 (liq) at -164C = 0.464 g/cm3<br />The desnity of H2O (liq) at 25C = 1.003 g/cm3<br /><br />Therefore it would take about 1/8 the amount of energy to evaporate a given volume of methan at -164C, compared to the same volume of water at 25C.<br /><br />An equal heat input would evaporate a Titanian lake with 8x the volume of a lake on Earth.<br /><br />+++<br />Jon, I agree the depths of the lakes need to be known to understand the volumes. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[solanazehe]

Hi,<br />first I was a bit excited about these interesting findings, but then compared two images of the same region from different times.<br />Is there a known reason why even the very dark parts contain details that look identical on both images? If so, my conclusion would be that these areas cannot be filled by liquid. These details first seem like noise, but then one can see that even "offshore" they are arranged in the same way which is a hint they do not move in respect to each other.<br />I have not found any comments on that. They are very probably formed by liquid, but I doubt these dark areas are filled with liquid today. On the other side I have no knowledge on how radar instruments work, so my expectation could be wrong.<br />Thanks to any comments.

 

[centsworth_II]

<font color="yellow">"...even the very dark parts contain details that look identical on both images?"</font><br /><br />The smallest visible details would be larger than a football stadium.<br /><b><i>"SAR images may be the sharpest that Cassini can achieve on the surface <br />of Titan, with 350 to 1700 meter (1100 to 5600 foot) horizontal resolution."</i></b><br />http://www.planetary.org/explore/topics/cassini_huygens/instrument_radar.html<br /><br />If the details you are looking at are real objects, they could be pretty large<br />islets. If so, they could help in identifying shallow areas.<br /> <div class="Discussion_UserSignature"> </div>

 

[vandivx]

I don't quite understand who is talking on that supplied link but it says something about 'if you want future technology, you will have to wait decades for a mission'<br /><br />that strikes me as if Columbus called off his trip saying we'll wait for future technology and certainly his ships weren't anything one would have wanted to go out with on such journey, at least by today's standards anyway<br /><br />besides that I find it kind of hard to garner enthusiasm for methane lakes but that may be just personal (honey what swimming trunks will do for that, won't my spandex ones disolve in it?) <img src="/images/icons/smile.gif" /> , I suppose people are hungry for anything that 'moves' and is that way alive, anything that doesn't lie static for millions of years like it is on typical planet or moon<br /><br />it is depressing if you imagine that in the times when on Earth we had those shallow seas with Trilobites in them - that the planets and moons then were about the same as we find them today, the same craters, the same red spot on Jupiter and probably the same 'lakes' on Titan, sometimes I think we had better let the space exploration to some future generations<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[3488]

Excerpts from CICLOPS.<br /><br />Cassini encounters Titan for the 30th time on April 26, with a closest approach distance of only 980 km (609 mi). Like the last few encounters with Titan, this flyby (known as T29) will allow for imaging of the northern portion of Titan’s trailing hemisphere following closest approach. The cameras will observe the surface starting around 6 hours after closest approach, with ISS’ main mosaic from this encounter beginning around 12 hours after closest approach (geometry shown below at right). Cassini’s RADAR instrument will be in the driver’s seat for much of the close approach period, obtaining a Synthetic Aperture Radar (SAR) swath covering terrain similar to the swath obtained in February, during the T25 encounter (see PIA09182). This SAR swath will start in the eastern part of the dark region named Fensal, and continue north through Elpis Macula, finally ending up near the north pole, just north of the dark, lake-like features seen by ISS and RADAR during T25.<br /><br />On April 29, Cassini will observe Titan from a distance of 1.23 million kilometers (767,000 miles), allowing for images of Titan’s north polar region (on the trailing side) at image scales better than 7.3 kilometers (4.5 miles) per pixel. This observation was designed to study photometry of Titan’s atmosphere and surface, but it will also allow for continued monitoring of the large, Caspian Sea-sized dark region discovered in late February, and cloud features in Titan’s northern hemisphere. <br /><br />CICLOPS/JPL.<br /><br />==============================================================================<br /><br />I wonder if the SAR can be re-tuned to pierce the Hydrocarbon sea to reveal the form & depth of this 'sea'??<br /><br />Anyway, the upcoming observations should reveal more about it.<br /><br />Later on this year, Cassini will radar image Titan's south polar region, including Ontario Lac <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>