DAWN, Ceres, and Vesta

            On our last trip to JPL we learned about NASA’s DAWN mission. DAWN’s primary purpose was to observe the two celestial bodies known as Ceres and Vesta that orbit the sun from within the asteroid belt located between Mars and Jupiter. NASA’s scientists came up with DAWN out of the interest in learning more about the early stages of our solar system and how it initially formed.

            In the 18^th century astronomers mathematically predicted the presence of a planet in between Mars and Jupiter. On January 1, 1801 Ceres was discovered by Sicilian astronomer Giuseppe Piazzi. At the time Piazzi thought he had discovered a planet. Over the following decade more and more objects were discovered in this region of the solar system. The asteroid belt was discovered and Ceres was no longer considered a planet. In 2006 astronomers retitled Ceres as dwarf planet. After making calculations about the size and mass of Ceres, Scientists concluded that there must be a thick layer of water underneath the crust of the dwarf planet.

            On March 29, 1807 German astronomer Heinrich Olbers discovered Vesta, the second largest asteroid in the asteroid belt. Olbers was looking for evidence that Ceres and Pallas, the other asteroid Olbers had discovered, were fragments from a possible previously existing planet. Vesta has a large crater that is almost as long in diameter as the diameter of Vesta itself. The debris from the collision has become Vestoids that orbit near Vesta or have crashed down to earth as meteorites. Vesta consists of a cooled lava crust, a rocky mantel, and an iron and nickel core. Because of this some believe Vesta qualifies to be a protoplanet.

            One thing that draws the attention of astronomers to Ceres and Vesta is the difference in conditions between the to considering they are relatively the same distance from the Sun. While Vesta became very hot and dry overtime, Ceres remained cool and even retained water. It is also possible that Ceres has a thin atmosphere.

            The team of astronomers on NASA’s DAWN mission believes that by studying Ceres and Vesta they can learn more about the formation of planets and solar systems. They believe that Ceres and Vesta were on their way to becoming full planets until the larger celestial body Jupiter took up the resources they needed to continue to grow.

            On September 27^th back in 2007 DAWN launched. In July of 2011 DAWN reached its first target, Vesta. While orbiting Vesta DAWN closely observed the asteroid while taking clear photos of it to replace the blurry ones taken through telescope. A year later in 2012 it left Vesta to move on to Ceres. Dawn will reach Ceres in February of 2015. There it will conclude its primary mission. DAWN will be the first spacecraft to enter into orbit around one celestial body, then relocate to another celestial body and once again enter into orbit.