Posted on 09/08/2005 4:46:27 AM PDT by PatrickHenry
Saturn's tiny moon Enceladus is "absolutely a highlight" of the Cassini mission and should be targeted in future searches for life, Robert H. Brown of The University of Arizona, leader of the Cassini visual and infrared mapping spectrometer team, said last week.
Brown and other Cassini scientists attended a meeting in London last week and are at the 37th annual Division of Planetary Sciences meeting at Cambridge University this week.
"Enceladus is without a doubt one of the most spectacular things Cassini has seen," Brown said in a phone interview Thursday. "It's one of the biggest puzzles. It'll be a long time before anyone comes up with a good explanation of how Enceladus does what it does, and for a scientist, that's pure, unmitigated fun. Solving the biggest puzzles is the thrilling part of doing science."
Scientists got their first glimpse of Enceladus's geology when Voyager 2 flew by the icy bright satellite in August 1981. They were completely baffled. Voyager photographed areas of young, smooth terrain that told them that the moon must have been geologically active as late as 100 million years ago.
But nothing explained how tiny Enceladus -- only 314 miles across -- could get hot enough to melt. It seemingly doesn't have enough interior rocks for radioactive heating, an eccentric enough orbit for tidal heating, or enough ammonia to lower its melting temperature. After Voyager, researchers shelved Enceladus as an unsolvable problem for a while.
This year, Cassini turned its more powerful cameras and instruments on Enceladus during Feb. 17, March 9 and July 14 flybys. Results have stunned and delighted.
The diminutive moon turns out to have a primarily water vapor atmosphere tinged with nitrogen, carbon dioxide and other simple carbon-based molecules (organics) concentrated at its south pole. Its south pole is a hotspot, hovering at a relatively balmy minus -183 degrees Celsius compared to the expected temperature of -203 degrees Celsius.
Enceladus's south pole is a hotbed of geological action. The south pole region is cut by parallel cracks roughly 81 miles long and 25 miles apart. The cracks, dubbed "tiger stripes," vent vapor and fine ice water particles that have crystallized on Enceladus's surface as recently as 1,000 years to 10 years ago. The fine ice material is probably the major source of particles that replenish Saturn's outermost ring, its E ring.
"The kind of geophysical activity we see is quite likely being driven by liquid water below the surface," Brown said. Cassini hasn't seen ice geysers or ice volcanoes, but the lack of ammonia, and the sheer volume of water vapor escaping suggests there's pure-water volcanism on Enceladus, he added.
"We detected simple organics in the tiger stripes," Brown said. The simple organics include carbon dioxide and hydrogen-and-carbon-containing molecules like methane, ethane and ethylene. "Methane (basically natural gas) has probably been locked up inside Enceladus since the solar system formed and is now bubbling up through the vents."
The visual and infrared mapping spectrometer can't detect nitrogen, but Cassini's ion neutral mass spectrometer may have found nitrogen in Enceladus's atmosphere. All other results from these two very different instruments are entirely consistent, which gives Cassini mission scientists confidence in their results, Brown said.
"So you've got subsurface liquid water, simple organics and water vapor welling up from below. Over time -- and Enceladus has been around 4.5 billion years, just like Earth and the rest of the solar system -- heating a cocktail of simple organics, water and nitrogen could form some of the most basic building blocks of life," Brown said. "Whether that's happened at Enceladus is not clear, but Enceladus, much like Jupiter's moon Europa and the planet Mars, now has to be a place where we eventually search for life."
The $3.2 billion Cassini-Huygens mission is a joint venture between the NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington.
Heh, good one. Although I expect in a few centuries we'll either be extinct or no longer meat.
Jeeezzz, now I find out! That sure ain't what the realtor told me!
I'm pretty sure myself that Von Neumann probes are easy for advanced civilizations to make, but for what purpose? If it's to explore the galaxy, then we probably wouldn't even notice them zipping by. More importantly, unless they stuck around permanently, the odds would be low that one would've happened to visit in the past century, when we might have a decent chance of recognizing what it was, assuming we noticed it.
but what about Uranus?
The absence of Dyson spheres is easy to explain: they don't exist, because no one needs them. It's a rather crude solution to a problem (energy production) that we will probably solve more elegantly (fusion power) before we can even construct a Dyson sphere.
It's an interesting question. Let's assume, for argument's sake, that life exists out there. Let's even go further and assume that such life is sentient.
You don't have to be a theologian to realize that such a discovery would shake the foundations of all of our major religions.
What kind of life? Is it mostly germs or are there a lot of Klingons?
"Cool down in a couple of ways. One, ice. It melts. That takes heat."
First I don't know how much ice Ceres has, but the heat produced by friction as it enters the atmosphere will create a lot of heat. You may not get much here.
"Two, gets rid of the SO by the impact blowing it right off the planet."
You'll have to do a lot better here. Got some calculations?
"Three, it'll also set up a water cycle on a planet that currently doesn't have a lot with as much water as we have here on Earth. Water vapor clouds will block a bunch of the IR coming in from reaching the ground. That alone will reduce surface temps."
Now, I like this possibility. Is there enough water with Ceres? But even if the IR cannot penetrate water, it certainly doesn't penetrate Venus' current atmosphere. Boiled in aqueous acid is not good for life, even the extremophiles we find on Earth.
And why doesn't it photolyze in Venus' atmosphere? It must be made abiotically there, since we have no signs there is life as we know it on Venus.
Gasification processes are abiotic, but use bio stuff like coal and garbage as feed stocks. They produce hydrogen, carbon dioxide, carbon monoxide and small amounts of carbonyl sulfide and carbon disulfide.
I have always wondered if we are not simply a rare species immune to the almost universally fatal effects of radio waves. Maybe every other intelligent species in the galaxy simply finds radio emissions to be dangerous or otherwise intolerable and avoids us like we would a nuclear waste dump or an open sewer.
The question at hand is whether the carbonyl sulfide is itself a sign of life as we know it...
The presumption is that it does photolyze in Venus' atmosphere which is why its presence suggests an ongoing process, not past volcanism by example.
Coal, garbage, and feed stocks are regarded as unambiguous indicators of biological activity.
The process of its formation is abiotic. Hey, it's abiotic in volcanos.
Venus doesn't have any active volcanos. ;p
Look! I'm not saying there's life on Venus. I just think we should take a glance.. Is that so wrong??
Absolutely not. I just think your reasons are a little thin.
Darwinists with a sense of humor! A sick sense of humor but more than I expected! Thanks.:)
I'm not assuming an orbital insertion, then orbital decay to a drop. Just interplantary best speed and *SMACK*...
It's not just the carbonyl sulfide. The article also notes the high concentration of water vapor in the stratosphere, the scarcity of carbon monoxide as if something's removing it, the presence of hydrogen sulfide and sulphur dioxide in proximity to one another, and the mysterious dark patches on ultraviolet images of the planet.
That is a heck of a lot more than we have going for Enceladus! And the Venusian stratosphere would be the easiest place (amongst the usual suspects) to collect a sample as well.
I have heard that Sol is such a dwarf star, it would be almost invisible from Alpha Centauri.
I doubt we are very noticable, except for some radio chatter and nuclear blasts.
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