November 28, 2005 | David F. Coppedge

News from the Solar Neighborhood

Here’s a collection of recent items of interest under the sun.  (Don’t miss the big story above, too.)

  • My Rhea Lies Under the Spacecraft:  Cassini added another trophy to its moon collection Saturday, skimming just 300 miles above the surface of Saturn’s large moon Rhea.  (Saturday is named after Saturn, hey).  Rhea is the largest moon after Titan, and one of two (along with Dione) remembered from Voyager days as having wispy or feathery streaks on its leading hemisphere.  Now that Cassini has gotten in for a closer look, scientists found that the streaks are not frost deposits as formerly thought.  Instead, they are regions of sharp cliffs exposing bright water ice.  Rhea also has a prominent fresh-looking rayed crater.  Though made of ice, the surfaces of Saturn’s moons are frozen so hard, the ice has the properties of hard rock.  Impacts produce craters, therefore, very similar to those on our moon, complete with central peaks, rays and ejecta blankets.  The Cassini Imaging Team has put together a gallery of the best raw images; the complete set is available on the Cassini Raw Image Database.
  • Spiral Ring:  Saturn’s F-ring is one long spiral, according to an international team that proposed the new theory in Science (see report on and click link to the artist’s conception).  If so, this raises lots of new questions.  Prometheus and Pandora, long thought to shepherd the ring particles into the narrow ringlets, may actually act more like attack dogs.  The ring appears tenuous and dynamic.  The spiral structure appears unique, with no clear explanation leaping out of the data about how the spiral is generated and maintained.
  • Japan Mines an Asteroid:  The Falcon (Hayabusa) successfully gathered samples of asteroid Itokawa (see Planetary Society report).  This gives the fledgling Japanese space agency a first, especially if the samples are successfully returned in 2007 at The Outback (not the restaurant, but the real Aussie wasteland, out back and down under).  The asteroid appears to be a rubble pile of loosely-cohering material with few craters.  Though it visited a different type of object – a comet – Stardust will hit the tape first on January 15 when its samples parachute into the Utah desert.  Hopefully it will not make a crater like Genesis did.
  • Mars with Spirit:  The Mars Exploration Rover imaging team released a blockbuster to celebrate Spirit’s first “Martian Year” anniversary in Gusev Crater, complete with special effects.  If you wonder how Spirit was able to take a picture of itself in the distance, well, that’s Hollywood.
  • Next Mars Champ Doing Fine:  The hefty Mars Reconnaissance Orbiter, affectionately known as “Mr. O,” is halfway there.  Already, Mars Express seems a hard act to follow, but when MRO goes into orbit next March, its best-ever cameras and instruments are slated to send back more data than all previous missions combined.  Till then, we hear Opportunity, Mars Odyssey, and Mars Global Surveyor hollering, “Hey, don’t forget me!”

These are great days of exploration.  At this time 200 years ago, Lewis and Clark were settling in at Fort Clatsop for a long winter.  At this time 100 years ago, Percival Lowell was squinting eagerly through his Lowell Observatory eyepieces, imagining cities and exotic inhabitants on Mars.  In such a short time, look what their country – their world – has done.  Space exploration did not evolve.  It is a demonstration of the power of intelligent design to order and direct natural materials toward purposeful ends.

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Categories: Solar System

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