Showing posts with label Moons. Show all posts
Showing posts with label Moons. Show all posts
Monday, January 14, 2013
APOTD: Tectonics on Enceladus
On Oct. 5, 2008, just after coming within 25 kilometers (15.6 miles)
of the surface of Enceladus, NASA's Cassini captured this stunning
mosaic as the spacecraft sped away from this geologically active moon of
Saturn.
Craters and cratered terrains are rare in this view of the southern
region of the moon's Saturn-facing hemisphere. Instead, the surface is
replete with fractures, folds, and ridges—all hallmarks of remarkable
tectonic activity for a relatively small world. In this enhanced-color
view, regions that appear blue-green are thought to be coated with
larger grains than those that appear white or gray.
Portions of the tiger stripe fractures, or sulci, are visible along the
terminator at lower right, surrounded by a circumpolar belt of
mountains. The icy moon's famed jets emanate from at least eight
distinct source regions, which lie on or near the tiger stripes.
However, in this view, the most prominent feature is Labtayt Sulci, the
approximately one-kilometer (0.6 miles) deep northward-trending chasm
located just above the center of the mosaic.
Near the top, the conspicuous ridges are Ebony and Cufa Dorsae. This
false-color mosaic was created from 28 images obtained at seven
footprints, or pointing positions, by Cassini's narrow-angle camera. At
each footprint, four images using filters sensitive to ultraviolet,
visible and infrared light (spanning wavelengths from 338 to 930
nanometers) were combined to create the individual frames. The mosaic is
an orthographic projection centered at 64.49 degrees south latitude,
283.87 west longitude, and it has an image scale of 196 kilometers
(122.5 miles) per pixel. The original images ranged in resolution from
180 meters (594 feet) to 288 meters (950 feet) per pixel and were
acquired at distances ranging from 30,000 to 48,000 kilometers (18,750
to 30,000 miles) as the spacecraft receded from Enceladus. The view was
acquired at a Sun-Enceladus-spacecraft, or phase, angle of 73 degrees.
Image: NASA/JPL/Space Science Institute [high-resolution]
Caption: NASA
Sunday, January 15, 2012
Newly Identified Lake on Europa Could Increase The Odds it Harbors Life
Though I have concluded that I am not a huge fan of the whole theme-week thing, as I suspected I would not be. There were at least two other planets I had intended to get to during last week's little experiment. Both are places that I think are particularly exciting worlds to ponder because of the unique set of conditions on each. And since it is my blog...At first glance, Jupiter's sixth closest moon would seem to be a near featureless, dead ball of ice, hardly the kind of place most would think of as being hospitable to life. But there's an ever growing body of evidence which clearly suggests that beneath it's icy surface, there is a deep sea of liquid water with an estimated volume of two to three times that of all the oceans on Earth, covering Europa's rocky interior. Most recently, researches analyzing data collected by NASA’s Galileo spacecraft in 1995-2003, identified what they believe to be signs of a body of water about the size of the great lakes sitting just a few miles beneath the planet's surface.
Then there are the dark lines which form the moon's most prominent features, which are actually deep cracks in the ice shell which covers it. Those cracks are believed to be formed by the gravitational pull of Jupiter essentially stretching and squeezing the planet like a rubber ball, causing the ice to crack and in turn, allowing warm salty water to flow up from beneath and fill them. Some theorize that process alone could generate enough heat to sustain a liquid ocean beneath Europa's ice sheets. But even if not, other processes like thermal venting from within the planet's core could also be contributing heat, as well as various minerals into the watery subsurface, minerals which could potentially aid in the development of life. There isn't yet any way of knowing for sure weather or not any of this is true of course. The idea that life might exist on Europa if it is, is a particularly speculative one. But it does make for an undeniably interesting thought experiment; trying to visualize how life might have developed on a world where ice becomes the atmosphere that shields you from the radiation of the sun, the vacuum of space, and serves to hold in the heat needed to sustain your existence. A world devoid of light, where there is no such thing as open air, and no way to leave the water into which you were born.
If there is life on Europa, it's a safe bet that it isn't advanced enough to ponder it's existence. But it's also within the realm of possibility to think that if there is life on the frozen moon, it might have managed to develop into something more complex than the types of microbial life we're most likely to find Mars. The odds are admittedly against such a thing on either account. But it's still cool to think about.
-CAINE-
Source: Wired Science
Image Credit: NASA/JPL
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