September 13, 2005 | David F. Coppedge

Mars and Moons Shed Cocoons

With so many spacecraft touring our solar system, there’s almost too much news to process.  Here are a few highlights, starting with Mars, then comets, asteroids, a Titanic puzzle, and what Cassini found mini moons ago.

  • Mars Ice Age:  Mars Express may have found evidence for deep ice deposits on Mars around the equator in the past, reports BBC News.  The article also states that, unlike Earth, Mars is subject to changes to its tilt axis of up to 15° due to the lack of a large moon.
  • No Mars Life from Methane:  “Forget microbes or Martians,” begins an article on Science Now.  According to veteran planetary scientist Sushil Atreya, the methane comes from a natural geological process called serpentinization.
  • Mars Gusev Crater Had Water:  A team analyzing Spirit data believes they have chemical evidence that water moved and deposited some of the rocks, according to a U of Washington press release.
  • Mars Missing Carbonates:  Sky and Telescope proposed a solution to the Martian missing carbonates problem: they never had a chance to form in the first place.  This is one of the “great mysteries” about Mars.  “Thus far, geologists have yet to find more than small amounts of carbonates on the Martian surface,” the article said.
  • Comet Tempel 1, a Gutless Wonder:  “Comet reveals crumbly guts” says News@Nature.  The texture appears to resemble “a loose collection of particles, like a weak sponge held together only by its own gravity.”  Investigator Michael A’Hearn thinks you could dig from one side to the other with your bare hands.  Science News made the Deep Impact mission its cover story for Sept. 10, and it also made prominent press in Science last week.  The presence of carbonates and other minerals on the comet, thought to require formation in liquid water, is also puzzling.  More detail on the spectral analysis can be found at Earth Files by Linda Moulton Howe who interviewed Dr. Carely Lisse of the Deep Impact team.
        Now that Comet Tempel 1 looks soft and crumbly, the mission planners of Rosetta are worried their spacecraft won’t find a solid surface to land on when it encounters another comet in 2011.  New Scientist is asking why in the last four comet encounters, the scientists’ predictions were all wrong.  In “Comet Tails of the Unexpected,” Stuart Clark begins, “We have now had four close encounters with comets, and every one of them has thrown astronomers onto their back foot.”
  • Cowabunga, Hayabusa:  A little-known Japanese spacecraft named Hayabusa has arrived at an asteroid.  The Japanese Institute of Space and Astronautical Science has its first close-up picture of asteroid Itokawa. If successful, it may become the first sample-return mission of an asteroid.  Find links to more images at Space.com.
  • Cigar Moon:  A planetoid on the outskirts of the solar system is spinning so fast, says Nature Sept. 8, that it is stretched into a cigar shape.  If orbital calculations are correct, its day is under four hours.
  • Spoken For:  Ring scientists have finally detected the elusive spokes in Saturn’s rings, reports the Cassini imaging team.  Their manifestation is apparently a function of solar incidence angle on the rings: the lower the sun angle, the more they appear.  With these facts, scientists are working on new models of spoke formation.
  • New Titan Landscape:  Cassini photographed a new region of Saturn’s moon Titan on Sept. 7.  The JPL press release shows an H-shaped region of contrasting dark and light areas named Fensal and Aztlan.  The dark patches are littered with light-colored “islands” that may be upwellings of water ice surrounded by hydrocarbon precipitates.  Individual images can also be found on the imaging website.
  • Titan Moonsoons:  A suggestion by Dr. Ralph Lorenz that Titan may have rare “monsoons” of liquid methane rain generated a headline on New Scientist.  (For context, see the Planetary Society blog by Emily Lakdawalla, who attended the meetings of the Division of Planetary Sciences of the American Astronomical Society in Cambridge last week, and reported what she heard.)  The idea is that Titan has long periods of dryness punctuated by heavy downpours, similar to American southwest deserts.  Govert Schilling wrote a short report for Science Now, called “Your Outdoor Adventure Guide to Titan.”  It’s a world of cryovolcanos, convective clouds, outgassing and condensing methane, and other strange things.
  • Titan Canyonlands Seen in Radar:  The radar data swath from the latest Titan flyby, feared lost due to a commanding error to the solid state recorder, was partly recovered and released Sept. 16 – and what a beauty.  In three stunning panoramas, scientists detected a methane-lake shoreline, a system of channels most likely scoured by methane rain, and a region of deep canyons up to 650 feet deep and 0.6 miles wide.  Some of the canyons can be traced for 120 miles.  As noticed before on other parts of the moon, there is a dearth of impact craters in all three frames.  See the Cassini press release for the full scoop, images and captions.  Space.Com also has a writeup.
  • Splash of the Titans:  Southwest Research Institute thinks that an exotic form of life may inhabit Titan, now that evidence for liquid hydrocarbons has been found.  BBC News reported on Jonathan Lunine’s contention that Titan, like Earth, occupies a “sweet spot” in terms of temperature and mass that drives active geological and atmospheric processes.  Liquid of any sort is all that is needed to get speculations about life flowing (see 07/26/2005 also).
  • Enceladus: Me Too:  Science Daily reported a claim by Robert Brown about the results from Saturn’s little moon Enceladus, that the “building blocks of life” could have formed in subsurface liquid water.
  • Miller Time Hangover  Back at Earth, Washington U scientists are speculating that there actually was a reducing atmosphere on the early earth, just like Miller and Urey supposed back in 1953 when they generated a few amino acids with their famous spark-discharge apparatus.  They deduced this by complex models about minerals in chondrites that they think made up the infant earth.  Geologists dispute the scenario, they admit, and getting a reducing atmosphere is not the only requirement for resurrecting the Miller scenario (see 08/15/2005, 06/16/2005).

Brown gets Stupid Evolution Quote of the Week for trying to stimulate funding by appeals to the L word:

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.  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.”   (Emphasis added.)

This is known as the JAWS theory of life (just add water, stupid).  We can enjoy the discoveries in the Golden Age of Planetary Science better without the mythoids and the noise of banging crutches on the funding trough (see Berlinski quote).
    Readers who appreciate more substance than the usual newspaper fluff are encouraged to go nugget hunting on the Planetary Society blog, provided one knows how to separate data from opinion.  There are very strange goings on out there (not only at Cambridge, but throughout the solar system).

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