Water Found on Asteroid Ceres

By Bill Andrews | January 22, 2014 12:07 pm
Ceres 2

An illustration of Ceres. Credit: ESA/ATG medialab

Looking for water is a pretty big deal on Earth, and an even bigger deal elsewhere. The chemical is not only vital to sustaining life as we know it, but it’s also an important clue that can reveal secrets about an object’s past. Astronomers had long been looking for it in one particular place, the asteroid belt between Mars’ and Jupiter’s orbits, and it looks like they finally found it — on Ceres, one of the belt’s most enigmatic bodies.

Ceres, SRSLY

Ceres has been in the news, off and on, ever since its discovery in 1801. Initially considered a whole new planet, it was later demoted (just like Pluto) to dwarf planet status because it turned out to be just one of many similarly tiny objects named asteroids. About the size of Texas, and dwarfed by our moon (and by Pluto), Ceres is still a pretty big deal: it contains about a quarter of all the mass in the asteroid belt.

Astronomers had found evidence suggesting Ceres had water before, and they’d long suspected it was made up of an icy mantle surrounding a rocky core. But a paper in today’s Nature shows conclusively, for the first time, actual observations of water on the dwarf planet.

Specifically, the authors using the European Space Agency’s Herschel Space Observatory detected two sources of water vapor spewing about 6 kilograms of water into space per second. Since there are two sources, that indicates that the presence of water is a more permanent phenomenon, and not just the temporary result of something like a recent impact with an icy body.

Water World

The authors suggest that the water vapor could have two causes: the direct sublimation of exposed water ice into vapor, similar to a comet’s behavior; or cryo-volcanism, where geysers or ice volcanoes directly rocket the stuff into space. This confirmation that the asteroid really does have stores of water (possibly rivaling the amount of freshwater on Earth) also suggests that Ceres formed farther from the sun that it currently resides. Other, drier asteroids were likely spots of hot volcanic activity, suggesting they originated closer to the sun.

And if it does turn out to be acting like a comet, it would further blur the lines between asteroid and comet. Once upon a time, astronomers considered them distinct, dissimilar objects: asteroids were dry rocky bodies between Mars and Jupiter, and comets were icy wet ones from beyond Neptune. But recent discoveries have been showing them to be more alike than thought, suggesting maybe they have origins and structures in common, with the differences only arising because of where they’ve traveled.

It’s great timing for the discovery as NASA’s Dawn probe is on its way to Ceres, likely arriving in orbit there in February 2015. The more astronomers know about the dwarf planet beforehand, the better they’ll be able to make use of Dawn’s instruments to answer specific questions. It’s an exciting time for Ceres research and water-hunting alike!


CATEGORIZED UNDER: Space & Physics, top posts
  • Greg Zsidisin

    Need to git there fast ‘n cap them wells! ))

  • http://blogs.discovermagazine.com William Stolley

    Now if the headlines read: Gold found on asteroid! You’d find all the space funding in the world.

    • Matt Secessionist Gadsden

      Pretty ignorant comment. If water was scarce it would be worth more than gold. In other words, it’s not worth mining water, period. There’s no purpose to it.

      • ian gardner

        Actually as a use for fuel and human needs the cost to carry it into space probably is close to the cost of gold

  • http://laurele.livejournal.com laurele

    Both Ceres and Pluto ARE whole planets, and their demotions should be rejected. Neither is one of many similar tiny objects. Unlike the majority of objects in the asteroid belt or Kuiper Belt, Ceres and Pluto are spherical, meaning they are massive enough to be rounded by their own gravity. This makes them complex worlds with geology and weather. Both are likely geologically differentiated into core, mantle, and crust. Both may very well have subsurface oceans. All of these make Ceres and Pluto very different from tiny, shapeless asteroids shaped only by their chemical bonds. Ceres and Pluto have all the same structure and processes as the larger planets; they just happen to be smaller. This is why dwarf planets should be viewed as a subclass of planets, which was the intention of Dr. Alan Stern when he first coined the term back in 1991.


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