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.
