Dawn imaging leaves mystery of bright spots unanswered


An enhanced colour view of the surface of Ceres.
NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

NASA has released the first detailed look at dwarf planet Ceres with a colour image that reveals the diversity of the surface of this planetary body. But the data fails to explain the mysterious bright spots – as many as 10 – that have puzzled scientists.

Differences in morphology and colour across the surface suggest it was once an active body.

"This dwarf planet was not just an inert rock throughout its history. It was active, with processes that resulted in different materials in different regions. We are beginning to capture that diversity in our colour images," said Chris Russell, principal investigator for the Dawn mission, based at the University of California, Los Angeles.

The Dawn mission made history on 6 March as the first spacecraft to reach a dwarf planet, and the first spacecraft to orbit two extraterrestrial targets. Previously, Dawn studied giant asteroid Vesta from 2011 to 2012.

Images from Dawn's visible and infrared mapping spectrometer (VIR), highlight two regions on Ceres containing bright spots.
NASA/JPL-Caltech/UCLA/ASI/INAF

Ceres is believed to be 25% water ice by mass. But the latest imagery has failed to answer the question of what the mysterious bright spots on the body are.

"The bright spots continue to fascinate the science team, but we will have to wait until we get closer and are able to resolve them before we can determine their source," Russell said.

Dawn's imaging spectrometer shows that the temperature of the brightest of the spots is similar to its surroundings, while another lies in a region that is cooler than the rest of the surface.

"The bright spots continue to fascinate the science team, but we will have to wait until we get closer and are able to resolve them before we can determine their source," said Russell.

Dawn begins its first intensive science phase on April 23 at which time it will scan the surface from a distance of 13,500 kilometres.

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