Given it is still a virtually unexplored part of out Solar System, will the Dawn spacecraft uncover something new from Ceres?
By: Ringo Bones
Since its launch in 2007, there has been scant press coverage on the Dawn spacecraft and its intended destination – a region in our Solar System that lie between the planets Mars and Jupiter called the asteroid belt. Besides some Earth like asteroids fictionalized in the first season of The Twilight Zone, it seems that the asteroid belt is an out of sight out of mind part of our Solar System. Fortunately, the recent pictures sent by the Dawn spacecraft has slightly peaked everyone’s interest of these so-called “dwarf planets” – as they are now called by the International Astronomical Union – that reside in the asteroid belt.
As of Friday, March 6, 2015, the Dawn spacecraft entered the orbit of Ceres. According to the mission’s chief engineer Marc Rayman at NASA’s Jet Propulsion Laboratory, which manages the 473-million US dollar mission says: “It went exactly the way we expected. Dawn gently, elegantly slid into Ceres’ gravitational embrace.”
Ceres is the second and final stop for Dawn, a robotic spacecraft that was launched in 2007 on a voyage to the main asteroid belt, a zone between Mars and Jupiter that’s littered with rocky leftovers that dates back from the formation of the Sun and the planets some 4.5 billion years ago. Dawn will spend 16 months photographing the icy surface of Ceres. Dawn previously spent a year at Vesta – the only “dwarf planet” of the asteroid belt that can occasionally seen with the naked eye from the Earth’s surface, exploring the asteroid’s surface and sending back stunning close-ups of its lumpy surface before cruising onto the Texas-sized Ceres, the largest object in the asteroid belt.
The 4.8 billion kilometer trip was made possible by Dawn’s ion propulsion engines which provide a gentle yet constant acceleration and are more efficient than chemical-based rocket thrusters. As Dawn approaches Ceres, it beamed back the best pictures ever taken of the “dwarf planet”. Some puzzling images revealed a pair of shiny patches inside a crater – signs of possible ice or salt – which is something that can’t be seen by earthbound telescopes. Marc Rayman says that the Dawn spacecraft is currently in Ceres’ shadows and won’t take new pictures until it emerges in April, he said.
Since its discovery in the evening of January 1, 1801 by the Italian astronomer Giuseppe Piazzi, Ceres has intrigued generations of astronomers. Ceres measures 965-kilometers (600 miles) in diameter and is named after the Roman goddess of agriculture and harvest. It was initially called a planet before it was demoted into an asteroid and more recently classified as a “dwarf planet”. Like true blue planets, dwarf planets are spherical in shape because their size or mass generates enough gravitation for it to attain hydrostatic equilibrium and thus attaining a spherical shape unlike the smaller oddly-shaped asteroids.