Our best image of the dwarf planet Ceres as seen by the Hubble Space Telescope and processed for contrast only shows the little planet as near featureless ball
The Magellans and Columbuses of our time are not Internet moguls or search engine developers. Present day explorers of the edge of far-flung frontiers include patient scientists extracting every last photon from the edge of the solar system through powerful machines on land and orbiting above, and most especially sturdy robotic probes powered by ions and inertia plying the lonely, cold ocean of interplanetary space. One of those outposts has reported back a fascinating discovery.
On the Earth there is a geographic snow line, a wobbly circle around both Poles where water stays frozen all year long. Our solar system also has a snow line of sorts, an imaginary circle around the sun where water forms into ice and can persist, from tiny grains of ice making up Saturn's sparkling rings to giant snowball moons and comets in the outer system. Water, as it turns out, is quite common in our solar system and that's a big deal. It's useful for lots of things, the primary constituents, hydrogen and oxygen, are critical to the exploration of space. And astro-biologists now believe water is also the most important single ingredient for life. So it was with great excitement and no small amount of hype that the Herschel Telescope found evidence for water spewing off the surface of one of the most mysterious objects in our solar system: Ceres, named after the Roman goddess of grain and fertility.
Ceres was discovered in 1801 by Giuseppe Piazzi and originally classified as a planet. But other astronomers quickly found other objects orbiting in the same band now called the Asteroid Belt. Ceres is the largest asteroid or smallest planet known, depending on what classification system used. But whatever it ends up being called, Ceres is a mysterious, dim object with enormous potential for science and, possibly, one day industry.
We know very little about it. But this week the Herschel Space Telescope detected signs of watery emissions from its dark surface and that has the planetary science community buzzing. What is Ceres? Is it a respectable Kuiper Belt Object that migrated in close to the sun or a planetary embryo suffering from arrested development that grew in situ?
Join us below the fold for more of the little we know of this ancient, tiny world.
Scientists know it lays just inside the water frost line, so there shouldn't be ice on its surface; it would have long ago sublimated into space like dry ice does on Earth. There must be a dusty covering at least. There are no large bodies like a primary planet or other moons that could cause tidal flexing, the phenomenon that leaves the Jovian moon Io the most volcanically active body in the soar system and the Saturnian moon Encledeus blasting out water like Old Faithful on steroids. But Ceres does live in a violent neighborhood, residual heat from past impacts could certainly keep it warm. The asteroid has an elongated orbit compared to most planets and is tilted 10 degrees to the ecliptic, so it would experience significant seasonal and orbital changes over the course of its 1,680 day "year."
Dr. Michael Brown, co-discoverer of several trans-Neptunian worlds and author of How I Killed Pluto and Why It Had It Coming noted that "Ceres has always been a bit of an oddball in the asteroid belt, and because of its relatively low mass, scientists have suspected that it is made, in part, of ice. Now it seems that some of that ice is vaporizing or melting and jetting off into space, making Ceres look more like a huge comet than a rocky asteroid."
Dr. Alan Stern, principal investigator of NASA's New Horizons mission to Pluto and beyond explained: "The discovery of water vapor plumes emanating from Ceres, a small planet in the asteroid belt, is simply astounding. It's sending a lot of scientists back to drawing boards to understand how such geysers could be powered on Ceres, and its further raised expectations for the arrival of NASA's Dawn mission in orbit around Ceres early next year."
That's the good news: in this case, finally, we're going to get some hard data real soon! The ion-powered Dawn spacecraft, illustrated right, will arrive to closely examine the enigmatic little world about one year from now. In fact, we should be getting better images than any we've ever had for several weeks beforehand as Dawn chases the mysterious object down. And if that's not good enough, just a couple of months later, New Horizons will beam back better pictures of Pluto and its moons than we've ever had, allowing us to compare and contrast deep space objects with Ceres. That combination could well lend insight into the origin of both bodies, paint a much clearer picture of the early and violent history of our solar system, and could even shed light on how solar systems form in general.
In terms of pure futurist speculation, Ceres has an unusual set of properties that could make it a critical exploration and industrial hub. It seems to have water, it probably has impact craters and basins all over it, made by all kinds of smaller objects colliding with it, including nickel-iron or perhaps even platinum group metal-rich asteroids. Perhaps most interesting of all, if we want to dream, is Ceres spins about once every nine hours and its surface gravity is less than 3 percent Earth-normal. That means a space elevator would be completely practical using materials we already have. One day Ceres could surrounded by artificial rings, with elevator spokes reaching nodes on the ground.
If so, someday, it might be venting to beat the band, a new and semi-permanent naked-eye comet fixed in the ecliptic, as automated machines crawl over and through it, collecting and transferring resources to a growing off-world civilization. It could become the gateway to the outer solar system. And once we get that far, out past Pluto where only the comets coast through the night, the stars will be the only logical place left to go.
