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Jan 22 2014

Water found on dwarf planet Ceres

600px-Ceres_optimized

The headline to the link article below is a bit over the top. It reads “Is there life on Ceres?” The answer is, we have absolutely no way to know that because that pic above represents the best we’ve got. Ceres is tiny, distant, and dim. But our knowledge of this enigmatic world is about to change radically:

NBC — “This is what you might call the ‘smoking gun,’” Mark Sykes, CEO and director of the Arizona-based Planetary Science Institute, told NBC News. “The implications could be huge for the future of astrobiology and planetary exploration.”

Sykes wasn’t involved in the Nature study, which is based on data from the European Space Agency’s Herschel Space Observatory. Nevertheless, Ceres is close to his heart: He’s a co-investigator on the $466 million Dawn mission and has long suggested that the dwarf planet might possess subsurface liquid water — and perhaps even traces of life. Reservoirs of water
The findings from Herschel don’t go nearly that far, but they do provide the strongest evidence yet that Ceres contains reservoirs of water ice. Past missions turned up indirect evidence for water, but nothing conclusive. It took Herschel’s sensitive HIFI infrared detector to pick up the spectral signature of water vapor, apparently emanating from two dark spots on Ceres’ surface.

At first this puzzled me with visions of ice geysers like we’ve seen elsewhere. Ceres is a free orbiting dwarf planet with no known satellites and way out from the sun. There can be no tidal flexing, and you’d think water-ice near the surface would have either escaped over the last four billion plus years or be safely sequestered away.

But all Herschel detected was minute traces. So if that’s confirmed, it sounds like it’s wafting out very slowly in tiny amounts. And Ceres lays right on the boundary of the solar system’s frost line, the point where incidental insolation falls below the freezing point of water. Eccentricity in its orbit could tip it back and forth just enough that some small traces of water escape. Plus, Ceres is a in violent neighborhood with no atmosphere to ward off even smaller objects. A few hits by objects on the order a 100 meters every million years or so would sure stir things up. Ceres also rotates about once every nine hours. Pretty fast. Between that and the low gravity, just under 3% earth normal, you could easily build a space elevator around Ceres with existing materials.

But what’s important is there is probably water just below the surface, perhaps a good bit. Water is useful, it’s the solution for all of life as we know it, not to mention it contains oxygen and hydrogen which are also both very useful to space exploration. NASA’s Dawn spacecraft will arrive in mid Feb of 2015 and we’ll probably start getting better images a few months beforehand.

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  1. 1
    jnorris

    But all Herschel detected was minute traces.

    At present, there are only minute traces of water in the Ohio River from West Virginia to the downstream. So there’s hope for Ceres.

  2. 2
    Randomfactor

    That’s why Asimov called it “the world, Ceres.”

    OK, it was mostly for the pun…

  3. 3
    StevoR : Free West Papua, free Tibet, let the Chagossians return!

    @ ^ Randomfactor : Yes indeed. Great essay that.

    I’m still hoping to see Isaac Asimov’s prediction :

    “I consider it quite conceivable that the day may come when Ceres will be the astronomical centre of the solar system.”
    - Page 66, chapter 5 “The World Ceres” in ‘The Tragedy of the Moon’ by Isaac Asimov, Mercury Press, 1973.

    Comes true someday!

    I’m not surprised by this discovery since I thought we knew Ceres to be watery for many years – in fact , another quote from years ago already claims :

    Once thought to be rocky, we now believe Ceres may contain 200 million cubic kilometres of water in its mantle. This is more than the amount of fresh water on the Earth.
    - Page 10, “Ceres may be a failed miniplanet” by Jeff Foust in Astronomy Now magazine, November, 2005.

    But this is nonetheless a really good discovery and a great write up here – shared, cheers Stephen “DarkSyde” Andrew!

    One last point (and quote) I can’t resist noting that Ceres sure looks like a planet to me in that picture – nor am I alone in that way of thinking either :

    “… he had left out a planet. It was not his fault; everyone leaves it out. I leave it out myself when I list the nine planets, because it is the four-and-a-halfth planet. I’m referring to Ceres; a small but respectable world that doesn’t deserve the neglect it receives.”
    - Page 63, chapter 5 “The World Ceres” in ‘The Tragedy of the Moon’ by
    Isaac Asimov, Mercury Press, 1973.

    I second that – whether you call it a planet or not (& I admit I’m still getting used to no longer thinking of Ceres being the largest asteroid too!) Ceres is certainly one remarkable and noteworthy little world.

  4. 4
    Robert B.

    Really, it’s not all that far away, as celestial bodies go. Jupiter’s moons are further away and not much bigger, but we have much better images of them than that picture of Ceres above. The real problem is, we’ve never sent a camera to Ceres, so we have to image it from Earth. The full-size planets get all the love (where “love” here means “NASA missions.”)

  5. 5
    =8)-DX

    The full-size planets get all the love (where “love” here means “NASA missions.”)

    I thought *love* always meant “throwing large shiny objects at and obsessively photographing at great expense”.

  6. 6
    Scr... Archivist

    … you could easily build a space elevator around Ceres with existing materials.

    That’s an interesting idea. Should we experiment with the engineering and construction of space elevators on uninhabited worlds before we try them on Earth? Once we know the basics, we could adapt our experience to different conditions.

  7. 7
    StevoR : Free West Papua, free Tibet, let the Chagossians return!

    @ ^ Scr… Archivist : The answer to that is – yes.

  8. 8
    Amphiox

    The idea that Ceres, by straddling the snow line, could be going through freeze-thaw cycles as it orbits reminds me of a thought I first considered when thinking about short period comets that melt and sublimate on close passage to the sun, only to re freeze when further out.

    With this kind of orbital dynamic on an icy body, is this not thermal cycling? And would this not be expected to be promoting some interesting sorts of prebiotic chemistries?

  9. 9
    Amphiox

    Re @6 and @7;

    I would say it is quite a bit easier to start the experimenting here on earth than trying to go to another world to do that foundational work. The challenge of just getting to Ceres with the people, materiel and equipment probably outweighs the greater technical challenges posed by earth’s stronger gravitational field.

  1. 10
    Water found on dwarf planet Ceres | EveryDayNewsScoop

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