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NASA's Dawn spacecraft is set to enter orbit around Ceres the second of two dwarf planets it set out to study in when it launched in 2007

Discovered in 1801 by Giuseppe Piazzi and was once considered a planet, Ceres has long fascinated astronomers from afar.  This celestial body resides in the inner solar system within the asteroid belt located between Mars and Jupiter.  It is the largest body in the asteroid belt.

Ceres was classified as a dwarf planet along with Pluto and Eris in 2006 as part of a three-way categorization by the International Astronomical Union (IAU) to create two distinct classes of objects for the planets category.

In recent years interest in Ceres has grown, in part, due to the presence of water ice on its surface. Researchers speculated that there might be subterranean oceans.  And where there's water, there's potentially life.  Interested was mounting fast to take a closer peek.

Solar system

Ceres speculative model
Diagram show Ceres' position in the solar system (top) and an artist render of Ceres' hypothetical ocean.
[Image Source: Amazing Astronomy (bottom); SolStation (bottom)]

Now mankind is getting that peek with NASA's Dawn Mission.

Launched in 2007, NASA's Dawn spacecraft is a part of the Discovery Program and managed by Jet Propulsion Labratory at Cal Tech Pasedena.  Ceres isn't Dawn's only target dwarf planet in the Asteroid Belt.  Its first mark was 4 Vesta, the second largest known asteroid after Ceres.   

Dawn Probe
An artist's rendering shows the ion thruster-driven Dawn space probe. [Image Source: NASA]

Dawn entered 4 Vesta's orbit in July of 2011 and stayed there for about a year before jetting off to its next mission -- Ceres.

4 Vesta
The probe diligently mapped out Vesta (brown is older sediments, colorized are from certain impacts). [Image Source: Wikimedia Commons/NASA]

Dawn is expected to entered Ceres' orbit later this week on March 6.  The Dawn probe is the first exploratory probe to utilize ion thruster technology.  Thrust is produced via a trio of xenon ion thrusters, which offer 90 mN of combined thrust.  It took 275 kg (606 lb) to get to 4 Vesta's orbit.  By the time the probe reaches Ceres -- its final destination -- it will have shot off an additional 110 kg (243 lb) of ionized xenon.

With the probe already providing key insight into 4 Vesta's composition and solar evolution, hopes are high that even greater insights will be provided into Ceres' composition.

Dawn spacecraft orbit
NASA's Dawn spacecraft travels from launch to Vesta to Ceres [Image Source: jpl.nasa.gov]
 

"Studying Ceres allows us to do historical research in space, opening a window into the earliest chapter in the history of our solar system," said Jim Green, director of NASA’s Planetary Science Division at the agency’s Headquarters in Washington. "Data returned from Dawn could contribute significant breakthroughs in our understanding of how the solar system formed."

Already Dawn is beginning to provide insight about Ceres.  Upon its approach it's spotted a number of bright spots, which researchers are currently puzzling over.  NASA scientists say the feature has not been observed in other planets or objects in Earth's solar system.

Comments JPL geophysicist Carol Raymond, who is leading the investigation:
They’re literally fossils that we can investigate to really understand the processes that were going on at that time.  The team is really, really excited about this feature because it is unique in the solar system.  And we will be revealing its true nature as we get closer and closer to the surface. So the mystery will be solved, but it is one that’s really got us on the edge of our seats.

The Dawn probe has been busy tweeting on Twitter's microblog (@NASA_Dawn) about the phenomena an exciting pictures it's snapped of the dwarf planet: The bright spots correspond to locations on Ceres surface where water was seen ejecting into space, as spotted by Earthbound observatories.  The water sprays give further hint at an underground unseen ocean and the elusive possibility of extraterrestrial life.  They also provide an intriguing mystery as the researchers explore the link between the bright spots and the sprays.

With the arrival and orbit around Ceres, Dawn will become the first spacecraft to orbit two destinations in the solar system. During its orbit around Ceres, Dawn will be logging scientific data over several months as it orbits at a range of distance above the surface from 8,400 miles down to 233 miles during its close orbit examination.

The probe will spend roughly a year in orbit around Ceres.  It is expected to maintain a stable orbit and thus will become the first manmade permanent satellite placed in orbit around the dwarf planet Ceres.

Sources: NASA, Jet Propulsion Laboratory, Twitter (@NASA_Dawn, LA Times





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