Today’s factismal: There is more water on the planet Ceres than there is fresh water on Earth!
You’ve got to hand it to plucky Ceres. Originally just called a planet, it was “reclassified” three times into being a “minor planet”, and asteroid, and a “dwarf planet” (most planetologists consider it to be a planet, no matter what the IAU says). But even worse than the constant reshuffling of its designation is the litany of woes it has faced. It was one of the last things to form in the asteroid belt and had its growth “starved” by near-by Jupiter which either ate the rocks that should have helped Ceres triple in size or tossed them into the void. After if formed, the interior of Ceres separated into a rocky core that was heated by the radioactive decay of aluminum and a slushy mantle made up of water and ice with a thin layer of rocks on top. And that wasn’t all; just as the face of the Moon was scared by the impact of rocks during the Late Heavy Bombardment, so, too, did Ceres suffer from scores of impacts. The largest of these formed a fuzzy white patch that is just barely visible in the best terrestrial telescopes; we call it Piazza, after the discoverer of Ceres.
That strange interior and scarred exterior are part of the reason that Ceres fascinates. The interior may just be warm enough today to allow a thin (50-100 mile thick) layer of water to exist in its interior.That layer holds more water than can be found in all of the lakes and rivers on Earth. Given the heat and water and rich mineral ooze, there are many who think that Ceres may harbor life! But if you want to watch that life, be prepared for a long trip. Before you get your space whale-watching gear on, you’d better pack enough groceries for a seven year long voyage.
That’s how long NASA’s DAWN spacecraft has been traveling. Launched from Earth on September 27, 2007, the DAWN spacecraft has been pushing its way toward Ceres using an ion thruster. This revolutionary rocket motor is too weak to lift anything off of Earth (they used a regular rocket for that) but is the champ when it comes to efficiency. Over the past seven years, DAWN’s ion engine has carried it from Earth to Vesta (Ceres’ little sister) and is now bringing it to Ceres where DAWN will orbit forever. When DAWN reaches Ceres in just under a month, it will be the first spacecraft to orbit two extra-terrestrial bodies, ever!
Even better, the data from the DAWN mission is being shared with us, right now. All of the images taken while DAWN orbited Vesta are available and ready for us to look at, enjoy, and classify! That’s right – we get to do real science that will then be used to help us understand how the planets formed and how solar systems come together. If you’d like to help with that (or just want to look at some really cool pictures), then thrust yourself over to Asteroid Mappers: