How Dust Lightens Up The ‘Dark Side’ Of Rosetta’s Comet

How do you see a side of a comet that is usually shrouded in darkness? For the plucky scientists using the Rosetta spacecraft, the answer comes down to using dust to their advantage. They’re trying to catch a glimpse of the shadowed southern side using light scattering from dust particles in anticipation of watching the comet’s activity heat up next year.

Using Rosetta’s OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) instrument, scientists are diligently mapping Comet 67P/Churyumov-Gerasimenko’s surface features as it draws closer to the Sun. Funny enough, the shadowed side will be in full sunlight by the time the comet gets to its closest approach. This gives scientists more incentive to see what it looks like now.

The comet side is in shadow because its is not perpendicular to its orbital plane, the Max Planck Institute for Solar System Research stated. This means that areas of the comet can stay in shadow for months at a time. But using OSIRIS’ powerful receptors, scientists can get a few hints about what those surface features are, using dust scattering.

Playing with saturation levels in these images, scientists using the Rosetta’s spacecraft imaging system are able to get more information about surface features in the image at right. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

“For a normal camera, this tiny bit of scattered light would not help very much”, stated OSIRIS team member Maurizio Pajola from the University of Padua in Italy. A normal camera has eight bits per pixel of information (256 shades of gray), while OSIRIS’ 16 bits allow it to distinguish between 65,000 shades. “In this way, OSIRIS can see black surfaces darker than coal together with white spots as bright as snow in the same image,” he added.

The scientists were not specific in a press release about what they are seeing so far, but they said that in May 2015 they expect to get a lot more data very quickly — once the area goes into full sunlight.

Rosetta, a mission of the European Space Agency, has been orbiting the comet since August. Next Wednesday it will release a lander, Philae, that will attempt to make the first soft landing on a comet’s surface.

Source: Max Planck Institute for Solar System Research

Elizabeth Howell

Elizabeth Howell is the senior writer at Universe Today. She also works for, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.

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