Enceladus' Hot Surprise

[rhodan]

From Space.com: <ul type="square">Puzzling Hot Spot Found on Moon of Saturn<br /><br />In July, NASA's Cassini spacecraft made its latest flyby of Saturn's moon Enceladus, revealing an unexpected hot spot on the moon's south pole.<br /><br />The finding flipped everything scientists knew about Enceladus on its head, because what should have been a dead moon appeared to be geologically active and what was supposed to be the moon's coldest region turned out to be its warmest.<br /><br /> "This is as astonishing as if we'd flown past Earth and found that Antarctica was warmer than the Sahara," said John Spencer, an astronomer from the Southwest Research Institute in Colorado and a co-investigator of the Cassini mission.<br /><br />The finding could explain an old mystery concerning Enceladus, but it also presents a new puzzle of its own. <br /><br />Discovered in 1789 by a British astronomer, Enceladus is named after a mythological Greek giant. Despite its namesake, it is a tiny moon, only about 300 miles in diameter, and small enough to fit snugly inside the state of Arizona.<br /><br />The surface of Enceladus is coated in a thin layer of ice that reflects back nearly all of the sunlight striking it, making it the brightest object in the solar system apart from the Sun.<br /><br />Cassini's July flyby of Enceladus had it dipping within 109 miles of the moon's icy surface, its closest approach yet. In addition to the south pole hot spot, Cassini also revealed that the "icy veins" were actually a series of fractures on the moon's surface. Even more surprising, the fractures appeared to be active, violently spewing a slushy jet of warm water and ice into space.<br /><br />Together, the venting fractures and the hot spot provide strong evidence for geologic activity on Enceladus. If true, the findings could explain the moon's connection with one of Saturn's rings, a relationship that has puzzled scie</ul>

 

[jmilsom]

Each of Saturn's moons seems to be full of surprises. First Iapetus and this bizarre 'hotspot' anomaly with Enceladus. I wonder if one day we'll be able to walk over these moons and study them in detail!!! There has been some discussion of the Enceladus hotspot on the other Enceladus discussion thread on this forum. <div class="Discussion_UserSignature"> </div>

 

[Philotas]

Quite interesting discovery. This might make it possible for life to exist on Enceladus, if just enough water is melted below the ice.<br /><br /><font color="yellow">Cassini is scheduled to make an even closer pass of Enceladus in 2008, during which scientists hope to gather new pieces for the puzzle.</font><br /><br />Now that`s going to be really close! <br />What`s pity is that those images, as far as I understand, won`t be much better than those taken during the previous flyby because of the high velocity of the spacecraft.<br /> <div class="Discussion_UserSignature"> </div>

 

[vogon13]

Having the 'icy veins' explained as fracture derived seems to clear up (for me at least) the quandry of the one weird one that appears to travel up and over another 'vein'. Would not expect a water based 'lava tube' analog to be able to travel uphill, since a fracture would not respond directly to local slope conditions, this explanation seems quite reasonable. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[silylene old]

It is possible the localized temperature on Encelaudus is 300K or even higher. http://uplink.space.com/showflat.php?Cat=&Board=sciastro&Number=151667&page=3&view=collapsed&sb=5&o=0&fpart=9<br /><br />I posted this in an earlier thread, along with a graphic:<br /><i>As I understand it, the temperature from the IR measurement is the average temperature measured over the entire measurement area. The 110K may not be the exact temperature of the fissure; actually it's just one knowledgable person's estimate. All we do know is that the average of the area of the hot fissure and the area of the surrounding cold ice surface was found to be 91K. <br /><br />So I will make an estimate too.... <br />If the 5% of the area in the box is occupied by a fissure at a balmy 300K, and the 95% of the area of the box surrounding surface is a frigid 80K, then the average temperature seen by the detector = 0.05*300 + 0.95*80 = 91K. <br /><br />In my estimate, I assumed 5% of the fissure was actually open and shedding heat (this assumption made my numbers look good! Actually I wanted to illustrate that there might actually be some significant heat source if it is small and localized in the center of a cracked ice surface.) </i> <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>

 

[nexium]

Your conjecture seems reasonable. Because of the low mass, and thus moderate pressure ice melts at 273 degrees k, so 300k would be warm water, which would take minutes instead of seconds to refreeze at 91 degrees k air temperature. Neil