Water vapor observed venting from Ceres

  1. marcus

    marcus 24,100
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    2014 Award

    http://www.bbc.co.uk/news/science-environment-25849871

    Herschel space telescope press release:
    http://sci.esa.int/herschel/53125-herschel-discovers-water-vapour-around-dwarf-planet-ceres/

    Abstract of scholarly article published in Nature:
    http://www.nature.com/nature/journal/v505/n7484/full/nature12918.html
    Localized sources of water vapour on the dwarf planet (1) Ceres

    Michael Küppers, Laurence O’Rourke, Dominique Bockelée-Morvan, Vladimir Zakharov, Seungwon Lee, Paul von Allmen, Benoît Carry, David Teyssier, Anthony Marston, Thomas Müller, Jacques Crovisier, M. Antonietta Barucci & Raphael Moreno

    Nature 505, 525–527 (23 January 2014) doi:10.1038/nature12918
    Received 23 August 2013 Accepted 26 November 2013 Published online 22 January 2014

    The ‘snowline’ conventionally divides Solar System objects into dry bodies, ranging out to the main asteroid belt, and icy bodies beyond the belt. Models suggest that some of the icy bodies may have migrated into the asteroid belt1. Recent observations indicate the presence of water ice on the surface of some asteroids2, 3, 4, with sublimation5 a potential reason for the dust activity observed on others. Hydrated minerals have been found6, 7, 8 on the surface of the largest object in the asteroid belt, the dwarf planet (1) Ceres, which is thought to be differentiated into a silicate core with an icy mantle9, 10, 11. The presence of water vapour around Ceres was suggested by a marginal detection of the photodissociation product of water, hydroxyl (ref. 12), but could not be confirmed by later, more sensitive observations13. Here we report the detection of water vapour around Ceres, with at least 1026 molecules being produced per second, originating from localized sources that seem to be linked to mid-latitude regions on the surface14, 15. The water evaporation could be due to comet-like sublimation or to cryo-volcanism, in which volcanoes erupt volatiles such as water instead of molten rocks.
    ==endquote==

    The water vapor was seen by the European telescope HERSCHEL which operated 2009-2013.
    This telescope was positioned at the Sun-Earth L2 point, 1.5 million km straight out from Earth.
    If things go as planned, the spacecraft Dawn will arrive at Ceres in March of 2015 and will be able to observe surface features and activity up close.
     
    Last edited: Jan 22, 2014
  2. jcsd
  3. Nugso

    Nugso 159
    Gold Member

    Hi, marcus. Could you please tell me how we know it's a water vapor? Can we analyze something just by its 'apperance'?

    I'm sorry if it's explained in the articles you've shared. I tried waded through them, but couldn't really understand.
     
  4. D H

    Staff: Mentor

    Yes. That is the key purpose of remote sensing. Telescopes are, in a sense, remote sensing devices. Chemicals and elements exhibit very distinctive emission lines where the chemical undergoes some quantum mechanical change of state. One of the instruments on the Herschel telescope was a spectrometer. Spectroscopy is a very powerful tool for detecting elements and compounds, even in trace amounts. For example, if the spectrogram shows sharp spikes at 557 GHz and 1113 GHz, that means you are seeing water.
     
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  5. Nugso

    Nugso 159
    Gold Member

    Thanks, DH! So, it's kind of similar to the way we find out what kind of atoms the Sun has such as hellium?( I guess I read that part in Lawrence's book "A universe from nothing")
     
  6. So if Ceres has lots of water, does that make it a better colonization prospect then Mars?
     
  7. marcus

    marcus 24,100
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    2014 Award

    I suspect, in fact, that it will turn out to be a better prospect than Mars for an expanding self-sustaining human colony. I think robots are better suited for doing whatever needs to be done on the surface of Mars, if anything needs to be. They don't mind the dry, almost airless environment and are already doing fine as explorers.

    Settlement would depend on humans adapting physically and medically to 3% gravity and psychologically to living in sealed artificially lit subsurface ice caverns. The ice layer is estimated to be about 100 km thick, covered over with a thin crust of rocky rubble and mineral residue.

    If people want to inhabit Ceres they would be living like termites in large ice caves connected by ice tunnels. The population could expand into new living space by hollowing out more caves. There might be lakes and ponds on the cavern floors. There might be vegetation, some other animals perhaps. The people might enjoy aerial acrobatics in the 3% gravity, might be able to fly by flapping small wings with their own muscle power. It might be fun.

    Key conditions:
    A. Available nitrogen compounds in Ceres minerals---nitrogen is needed for protein.
    B. Power supply. How could humans on Ceres manufacture power plants to meet their growing needs for electric lighting?
    C. Genetic or pharmaceutical adaptation to low gravity. Is bone loss a longterm problem and how can it be addressed?

    In one sense Ceres 3% gravity is a PLUS. In other places (Earth, Mars,...) it can be a big deal just getting up off the surface---into orbit---or getting safely down. This is an obstacle to the practical exchange of material and equipment. At Ceres the escape velocity is way less than other nearby places humans might want to live. Escape velocity is only some 500 m/s.

    If humans develop a LIKING for iceball termite lifestyle then there are a lot more places open for them to live. The Earth seems to be a rather rare hard-to-find sort of planet. But iceballs are abundant. We have a dozen or so here in Solar System, some even believed to have subsurface oceans. They seem generic and favored by nature, so most likely equally abundant around other stars as well.

    I would advise any species capable of it to adapt to iceball lifestyle: learn to enjoy and thrive in it. :smile:
     
    Last edited: Mar 20, 2015
  8. marcus

    marcus 24,100
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    2014 Award

    Possibly important paper presented at recent LPS conference in Huston. Emily Lakdawalla reports on talk by Andreas Nathues
    http://www.planetary.org/blogs/emily-lakdawalla/2015/03191629-lpsc-2015-dawn-at-ceres.html
    Scroll down to where it says this kind of thing:
    ==quote Emily==
    ...Then he focused on the bright feature. It is located in the floor of a crater 80 kilometers in diameter. From its behavior as the globe rotates, he said, the bright feature appears to lie in a depression. The images that have been released to the public from the rotation animation do not show all of the photos of the bright feature, so the next point concerns images that I can't show you. "What is amazing," he said, "is that you can see the feature while the rim is still in front of the line of sight. Therefore we believe at the moment that this could be some kind of outgassing. But we need higher resolution data to confirm this." What he is saying is that as Ceres' globe rotates and the 80-kilometer crater's rim rotates into view, that rim should block our ability to see the bright feature on the floor of the crater. However, the bright feature is already visibly bright as the crater begins to rotate into view. Therefore, it must be vertically above the rim of the crater: it must be some kind of plume. "During the day," Nathues went on, "the feature evolves: it brightens. At dusk it gets fainter; at late dusk it disappears completely. We see this for cometary activity."
    ...
    ...
    Obviously, active outgassing on Ceres would be a big deal, if it really exists. Fortunately, Dawn will get much closer and will take much better images, which will hopefully confirm this discovery!
    ==endquote==
     
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