4 Jul 2018

Weird Bright Spots on Ceres Get a Close-Up from Dawn As Mission Nears End



SA's Dawn spacecraft has gotten its best-ever looks at the weird bright spots that speckle the dwarf planet Ceres.

Early last month, Dawn maneuvered its way to a new orbit around Ceres, an elliptical path that takes the probe within a mere 21 miles (34 kilometers) of the dwarf planet on nearest approach. That's more than 10 times closer than Dawn had gotten previously during its three-plus years at Ceres.

The views from this low altitude are amazing, as some newly released imagery of the 57-mile-wide (92 km) Occator Crater shows. [In Pictures: The Changing Bright Spots of Dwarf Planet Ceres


Occator's floor hosts odd bright deposits, which Dawn discovered during its approach to Ceres in early 2015. Subsequent observations by the probe revealed that the bright stuff, which also occurs at several other locations around Ceres, consists of sodium carbonate.

Scientists think this material was left behind when salty water boiled away into space. But it's unclear where exactly that water came from. Was it concentrated in reservoirs near the surface? Or did it snake up to the surface via fissures from deep underground?

The newly released photos of Occator, which Dawn captured on June 14 and 22, could shed light on this mystery by painting a more complete picture of the crater floor, mission team members said.

"Acquiring these spectacular pictures has been one of the greatest challenges in Dawn's extraordinary extraterrestrial expedition, and the results are better than we had ever hoped," Dawn chief engineer and project manager Marc Rayman, of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, said in a statement. "Dawn is like a master artist, adding rich details to the otherworldly beauty in its intimate portrait of Ceres."

The $467 million Dawn mission launched in September 2007 with an ambitious goal: to orbit and study Vesta and Ceres, the two biggest objects in the main asteroid belt between Mars and Jupiter. Vesta and Ceres — which are 330 miles (530 km) and 590 miles (950 km) wide, respectively — are building blocks left over from the solar system's planet-formation period, which explains the mission's name.

Dawn orbited Vesta from July 2011 through September 2012, when it departed for Ceres. The probe arrived at the dwarf planet in March 2015, becoming the first spacecraft ever to orbit two objects beyond the Earth-moon system.

Source - NDTV 

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