Staff writers
The latest images from NASA gives the clearest picture yet of the craters on Ceres, the dwarf planet that lies between Mars and Jupiter, and the shining bright material in them that have had observers baffled for months.
These images were taken from the spacecraft Dawn's lowest-altitude pass on – a distance of just 385 kilometres.
Among others, they show Haulani Crater (above), with a diameter of 34 kilometres, with evidence of landslides from its crater rim.
The enhanced false-colour view allows scientists to gain insight into the materials that make up the surface. In this image, bluish colours indicate relatively young ejected material.
"Haulani perfectly displays the properties we would expect from a fresh impact into the surface of Ceres. The crater floor is largely free of impacts, and it contrasts sharply in color from older parts of the surface," said Dawn scientist Martin Hoffmann from the Max Planck Institute for Solar System Research, Göttingen, Germany.
The crater is notable for the angular lines on its rim – most craters elsewhere in the solar system, including on Earth, are nearly circular, and scientists believe the hard edges on some of Ceres result from pre-existing stress patterns and a network of fault lines beneath the surface.
Scientists are also excited by the imagery of the 10-kilometre-wide Oxo Crater – the second-brightest feature on Ceres after the Occator crater's central area.
Oxo is unique because of the relatively large "slump" in its crater rim, where a mass of material has dropped below the surface – more evidence of active geology on Ceres.
Dawn science team members are also examining the signatures of minerals on the crater floor, which appear different from elsewhere on Ceres.
"Little Oxo may be poised to make a big contribution to understanding the upper crust of Ceres," said Chris Russell, principal investigator of the mission, based at the University of California, Los Angeles.
Data from Dawn managed to solve the puzzle of the bright spost, which scientists are now convinced consist of a mixture of ice and salts.
The spacecraft will continue on its low altitude mapping mission, collecting images of Ceres’ most prominent features and studying its materials and gravity until 30 June.
By then, the spacecraft will run so low on its hydrazine fuel that it can no longer point its instruments at Ceres’ surface or its antenna at Earth.
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