[FPSPACE] New Planetoid Opens Magical Possibilities
joberg at houston.rr.com
Fri Apr 9 20:40:27 EDT 2004
New Planetoid Opens Magical Possibilities
Space News, April 5, 2004
Page 15, 19
The British novelist, poet, and dramatist Eden Philpotts (1862-1960) once wrote that "the Universe is full of magical things, patiently waiting for our wits to grow sharper." The discovery of the distant planetoid called Sedna, and the growing realization of what it implies, is another wonderful fulfillment of that prophecy and of the profound cultural value of exploring space.
New discoveries about the Universe around us, in all its magical magnificence, don't just provide new facts for encyclopedias and quiz shows. They provoke unexpected questions and lead to surprising insights about both 'out there' and 'in here', back here on Earth and in our own minds.
The ice world Sedna has reminded all of us - not just the scientists - that the process of discovery is a UNITY. It's not localized, or distant, it's right HERE inside us.
At a NASA news media teleconference on March 15, Dr. Michael Brown of the California Institute of Technology described how his team's NASA-funded computerized telescopic search noticed a slow-moving object last November14that was soon recognized as the most distant member of the solar system ever observed. By tracking it for several months and by searching through archival photographs where it had earlier been spotted but not recognized, the astronomers soon mapped out its orbit.
"Sedna" is a character in an Inuit creation myth from northern Alaska, the creator of sea life, who dwells in cold darkness beneath the Arctic Ocean. The connotations of the name may be more prescient than even the scientists involved first thought, even if this object, probably slightly smaller than Pluto, is very cold, with surface temperatures in the - 400 deg F range.
Here's the mind boggler. Inside the planetoid - assuming it is a mix of half rock and half ice like other distant objects - temperatures will rise. There's radioactive heating from the rocks, and compressional heat from its formation eons ago. And the suspected existence of a small moon around Sedna provides yet another source of internal heating through tidal stresses.
Asked by a reporter if there might be regions deep beneath the surface where liquid water could exist, Brown called it "a very interesting question.” Planetary scientists have long been studying the processes by which icy worlds in the outer Solar System - such as Jupiter's moons Europa and Ganymede - can have liquid water oceans beneath icy crust. The mass of water in these oceans might make even the Pacific look like a rain puddle.
"As you dig down it will certainly get warmer," he answered. "But the truly frigid temperatures will quickly drain the original heat of the interior. "As for enough heat to maintain a deep layer of liquid water, he was open-minded: "My gut feeling is that it's unlikely," he concluded, "but it's not completely impossible."
One additional contribution to making such an ocean 'possible' is the chance that Sedna itself has a moon of its own, something that through tidal friction would churn up the heart of the planetoid and generate some warmth. Some astronomers have speculated that even Pluto, due to the tidal flexings from its large moon Charon, might have melted water deep below its icy surface.
The evidence for a moon of Sedna remains 'indirect', Brown explained, and is connected with the planetoids very slow (about forty days) spin rate – so unusually slow it suggests Sedna is gravitational 'locked' to a nearby moon orbiting with that same period. A new observation program by the Hubble Space Telescope will soon look for visual confirmation.
In wildly speculating on genuine "cold, dark seas" for Sedna, namesake of the Inuit creation goddess of the seas, astronomers realize that such heating sources are weak and often 'temporary'. That's in astronomical terms of course - they might last a billion years before dying out, for example.
The scientists will also need to consider how much of the planetoid's composition really is water. The first guess, that it is similar in composition to other objects at the edge of the solar system, is thrown into question by its unusual color, because Sedna is very red, second only to Mars of all known objects. Although some other icy asteroids are also reddish, due to the action of cosmic rays on their surface materials, these objects are very dark. Sedna, in sharp contrast, is highly reflective.
When asked to offer explanations for the planetoid's shininess, Brown would not. One newsman then asked him to just describe the different possible reasons for the visual appearance. "We are baffled," he admitted. "There aren't competing explanations -- I don't even have a single explanation." There is something about the composition, or the extreme cold, or the interstellar wind and radiation, or some combination of these and other factors, that has done something never before seen by any human being.
Until new data and new ideas arrive, speculation about the nature of Sedna can remain free-wheeling. And by far the wildest speculating deals with what might happen if you do have liquid water, and chemicals in the soup, and lots and lots of time - what sort of exotic chemistry and even biochemistry will you get? Or how about - biology?
Now, here's where discoveries OUT THERE really come home to roost. Even two decades ago this sort of question - the chances of life forming INSIDE an extraterrestrial ocean with a roof over it was almost literally 'unthinkable' because that wasn't "life as we know it". Then it turned out that Earth itself was overwhelmingly the abode of "life as we DIDN'T know it".
The revolution in Earthside biology in recent years is that MOST of Earth's 'biomass' - the weight of living stuff – is probably underground (and microscopic), and a lot of it doesn't depend on photosynthesis (on sunlight) at all. We didn't even know it was there only a few decades ago.
This was our conceptual flaw. When we used to say that Earth was the only possible abode of life in the Solar System, it was based on our misconception that SURFACE life (accustomed to sunlight, warm breezes, rain) was all there was. But many biologists are now coming to suspect that the conditions on which MOST of 'Earth life' exists -- underground, dark, wet, and chemically-fuelled -- are MUCH more common elsewhere in the Solar System.
Whether or not such eventualities are ever proved, just thinking about the possibilities has by itself propelled our life science concepts ahead. Questions are now being asked that were "unthinkable" before we began gathering clues about the range of possibilities in the Universe. And as our wits grew sharper and continue to grow sharper, more and more magical things - such as the new planetoid Sedna, its bizarre surface coloration, its phantom moon, its mind-blowing orbit, and its as yet unknowable interior contents - come into focus. There is no other word for such a mind-expanding process than - "magic".
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