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Sep 08 2012

Accretionary Wedge #49: Out of This World

T-4 and counting…

“No one regards what is at his feet,” Quintus Ennias, the father of Roman poetry, said. “We all gaze at the stars.” And so we do. Those cold points of light in our skies remained mysteries for so long, until we realized they were other suns. And if there were other suns, there could be other worlds.

And where there are other worlds, there will be geology.

The gravelly area around Curiosity’s landing site is visible in the foreground. Farther away, about a third of the way up from the bottom of the image, the terrain falls off into a depression (a swale). Beyond the swale, in the middle of the image, is the boulder-strewn, red-brown rim of a moderately-sized impact crater. Father off in the distance, there are dark dunes and then the layered rock at the base of Mount Sharp. Some haze obscures the view, but the top ridge, depicted in this image, is 10 miles (16.2 kilometers) away. Image courtesy NASA/JPL-Caltech/MSSS.

We can, so far, still only gaze at those stars, although our vision is getting clearer. But we’ve learned to regard what is at our feet. We have walked on another world. We have sent our machines to explore others, orbiting them, landing on them, taking photos and samples and returning wonders. But other worlds aren’t just out there. They’re right here, too, under our heels, in places we didn’t think to look for more than terra firma. We send bits of ourselves to other worlds; we’re just returning a favor. Other worlds have been coming to us for a very long time.

Geology was born on Earth, and it has always had a habit of looking down. Geology didn’t used to gaze at the stars; it regarded what was at our feet. But then we looked up, looked around, and will never see our universe the same way again.

I invited you to blast off for other worlds. But we begin right here, with rocks from space, brought to Earth by impacts and a little bit of Hollywood Space Geology while we’re at it.

Meteors

Metageologist: What came from outer space.

Study of earth’s early history removes any lingering doubts that earth can be studied in isolation from its surroundings. The earth formed within a dusty disc around the new sun 4.56  billion years ago. During the earth’s first few 100 million years it was constantly being struck by other pieces of debris. The best current theory for the formation of the moon is the ‘giant impact hypothesis’. This suggests that the proto-earth was struck by another proto-planet the size of Mars. The impact resulted in two separate blobs which formed the earth and the moon. The energy of such an impact left both bodies completely covered in a magma ocean. Any water in the earth would be boiled off, meaning that our atmosphere and oceans are all derived from water from comets that have hit the earth since. We are all made of star dust, but let’s not forget the comet juice.
My favourite link between the earth and beyond is only an idea so far, but a beautiful one. On earth we find rare meteorites that came from Mars and the moon. When one day we study the moon in more detail, perhaps we’ll find pieces of earth on there. The period when the most impacts hit earth (sending bits flying off) is also the time when we have the fewest rocks preserved on earth. What if the oldest earth rock still in existence is actually to be found on the moon?

Poikiloblastic: Six days in the crater, day three.

The plains surrounding Meteor Crater are afflicted with an excess of flatness. Aside from the crater itself, the only relief is from scattered blocks, mounds and low rises of Coconino Sandstone and Kaibab Dolostone. They are blemishes on the otherwise flat patchwork terrain surrounding the crater. Like the boulder on the hill, many large coherent blocks of ejecta excavated during impact were thrown out of the crater and now rest upwards of 300 feet above where they ought to. Three days in, we were no longer tourists; It was time for science. We started work to answer a few relatively simple questions: Where in the crater did those blocks originate? How big are they? What would it take to launch them tens and hundreds of meters to their current position?

Ann’s Musings on Geology and Other Things: Accretionary Wedge #49 -“other-worldly” geology.

It is this dry arid climate that lends itself so much to it being so alien and reminding you of ‘other-worldly geology places’.  Because to me that is the one thing that seems to make our planet so unique  – is its abundant water.

Movies

Geotripper: Accretionary Wedge #49: It’s just out of this world! Hollywood and the Cosmos.

Lots of Hollywood movies take place in space and on other planets, and since the director can’t go to the other planets, locales on Earth have to suffice. As geologists know, there are landscapes on our planet that do a good job of looking otherworldly, and so geology became a central part of the movie plot.

…We have ignition…

One of the most remarkable, most beautiful things we have done as a species, is discovered that some of the rocks beneath our feet came from far beyond our atmosphere. And we didn’t rest with studying them: we flew to the Moon and brought bits of it back. These rocks are remarkably beautiful under the microscope. If they don’t ignite a passion for exogeology, nothing ever will.

Minerology

Aerial Geologist: Accretionary Wedge #49: Optical Mineralogy in Space!

All in all, it was a unique and amazing experience for us to get a chance to examine these space rocks under the petroscope. The minerals were identifiable by us, while at the same time not typically looking like anything we had seen from our Earth rocks.

…We have liftoff!…

Granted, our first explorations didn’t quite get us to space, but let’s face facts: 70,000+ feet high in a balloon is pretty damned impressive!

Milestone

In the Company of Plants and Rocks: South Dakota’s contribution to the Death of Flat Earth.

I suppose the story of Icarus teaches a lesson about the dangers of over-ambition, hubris, arrogance.  Fortunately, the drive and curiosity of the human race are irrepressible, and many years later, as soon as technology allowed, mankind was back in the air trying to go higher and higher, to see what could be seen.

Now we head for the Red Planet. We’ve dreamed of it for thousands of years. Now we’re on its surface, exploring vicariously through our machines, and I have to tell you: a planet with no plants is a geologist’s paradise.

Mars

History of Geology: The Earth-like Mars, Meet the Martians, and I can tell you about Mars.

The outer rim of this crater provided an unique outcrop – soon named Burns-Cliff, after Roger Burns, who predicted the mineralogy of the Martian rocks (composed mainly of ultrabasic minerals, like Olivine, and ferric sulfate minerals) based on the preliminary results obtained by the Viking missions.
Along the slope of the cliff geologists recognized a succession of rock types, or facies, named informally “Burns-Formation“, the only extraterrestrial geologic formation at the time. The Burns-Formation consists almost entirely of sandstone with grains of basalt, oxides, silicates and evaporite minerals (Calcium and Magnesium- sulfates, chlorides and phosphates).

Magma Cum Laude: Danny Krysak: An out-of-this-world geologist (Accretionary Wedge #49).

Well, exogeologists, I’ve got a real treat for you. You know those photos that we all tweet and blog and comment on and drool over when they come down from Curiosity’s cameras? Well, I’ve got an interview with one of the camera team who is, quite literally, the first person on Earth to see some of those photos!

Slobber and Spittle: Earth Vs. Mars: Do Our Volcanos Measure Up?

After seeing this photo at the Astronomy Picture Of The Day (APOD), I naturally wondered how some of Earth’s other volcanoes stacked up against it.

Beyond Mars, we reach other planets, but though the gas giants are showy and impressive in telescopes, we’re not here for them. We’re captivated by their oddball moons, which have more intriguing geology than we had any right to suspect.

Moons

Rosetta Stones: Where Volcanoes Snow.

This is a world where volcanic plumes are sulfur dioxide snow, and are so large they can be seen from Earth orbit by the Hubble Space Telescope, and from Earth-based telescopes as outbursts of infrared. Tectonics are driven by tides rather than internal heat; volcanoes vent ultramafic lavas hotter than anything seen on Earth in billions of years. 425 volcanic centers, 70 of them currently active, rework the surface at a remarkable rate of 1 centimeter (over a third of an inch) per year. This world is 25 times as volcanically active as Earth, bumping us to second place for geologic activity, but is barely larger than our own Moon. It’s the only other planet in the solar system we know of that has active volcanoes. It claims the prize for longest lava flows.

Outside the Interzone: The Little Robot That Could… Visits Miranda!

The dive in to Uranus meant that some of the outer moons, which initially were more interesting to planetary scientists, would not be as well observable as had been hoped. And since there was no “scouting trip” by Voyager 1, there would be one chance and one chance only to see what that planetary system had offer. Miranda was not expected to be as interesting as other targets might be, but the path of the probe, and sun/moon illumination aspects would give ample opportunity to study that object. Good thing.

…Mission Control, the Eastwing has landed!…

Pretty incredible, what our species has done. We’ve not only sussed out many of this world’s secrets, but made a decent beginning at exploring the bizarre and bizarrely-familiar geology of other worlds. Someday, we’ll find our way beyond our own star. We’ll gaze on other star systems, and work out their geology, and perhaps have a beer on an alien outcrop under a strange star at the end of a long day’s exo-fieldwork. What will we find? What will be familiar, what different, what predicted and what never dreamt of in all those long nights of gazing at the stars?

In 2005, this image from NASA’s Hubble Space Telescope was used to identify two new moons orbiting Pluto. Pluto is in the center. The moon Charon is just below it. The newly discovered moons, Nix and Hydra, are to the right of Pluto and Charon. Image Credit: NASA, ESA, H. Weaver (JHU/APL), A. Stern (SwRI), and the HST Pluto Companion Search Team

6 comments

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  1. 1
    StevoR : Free West Papua, free Tibet, let the Chagossians return!

    Cheers Dana Hunter. I love this post. :-)

    Course Pluto has no less than five moons now.

  2. 2
    StevoR : Free West Papua, free Tibet, let the Chagossians return!

    .. And is still my favourite planet! Stuff the IAU.

  3. 3
    Lockwood

    Such a sweet topic, and such a great post. Thanks!

  4. 4
    Brian

    Geology on Mars should be called areology. Shouldn’t it?

    1. 4.1
      rq

      Has a nice ring to it, at any rate. :)

  5. 5
    F [is for failure to emerge]

    I finally managed to read all of them, and loads of the links. What a journey! Awesome Wedge.

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