In first, NASA craft orbits ‘fossil’ planet

In first, NASA craft orbits ‘fossil’ planet
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In a historical first, NASA’s Dawn spacecraft has entered orbit around a dwarf planet, which could presage untold new discoveries about the history of the solar system.

The 65-foot craft on Friday entered orbit around Ceres, a dwarf planet that is the largest body in the solar system’s asteroid belt between Mars and Jupiter.

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In coming months, the craft will circle the dwarf planet and beam images, maps and other data for scientists to study how planets are formed back to Earth.

"Studying Ceres allows us to do historical research in space, opening a window into the earliest chapter in the history of our solar system," Jim Green, the director of NASA's planetary science division, said earlier this week. “Data returned from Dawn could contribute significant breakthroughs in our understanding of how the solar system formed."

The mission is the first time a spacecraft has entered into orbit around a dwarf planet, a classification that does not qualify as either a planet or a moon. Pluto, which was once categorized as a planet, is the most well-known dwarf planet.  

Ceres is actually the second and final stop for Dawn, which was launched in 2007.

In 2011 and 2012, it explored the giant asteroid Vesta, the other massive body in the asteroid belt, and sent thousands of images back to scientists on Earth.

Exploration of both celestial bodies — whose path to becoming full-fledged planets was stunted by other bodies — is critical to learning about planetary evolution, scientists say.

"Both Vesta and Ceres were on their way to becoming planets but their development was interrupted by the gravity of Jupiter," said Carol Raymond, the deputy principal investigator for Dawn at NASA’s Jet Propulsion Laboratory, in a statement. "These two bodies are like fossils from the dawn of the solar system, and they shed light on its origins."

Ceres is much larger than Vesta and, unlike the very dry asteroid, is estimated to be about 25 percent water by mass.