Rosetta Shows First Glimpse Of Comet 67P’s Dark Side

Posted: Oct 4 2015, 6:24am CDT | by , Updated: Oct 4 2015, 7:03pm CDT, in News | Latest Science News


Rosetta Shows First Glimpse of Comet 67P’s Dark Side
Courtesy of NASA/JPL

The images of the dark, cold southern region will help understand the surface and environment of the comet.

Since August last year, European Space Agencies’ Rosetta spacecraft has been surveying a strange double-lobed comet 67P/Churyumov-Gerasimenko and is striving to collect data about its surface and the environment.

The spacecraft has remained unsuccessful in reaching the dark and cold regions around the south pole of the comet for a long time. But now Rosetta has been able to access this isolated place and has provided the first peek at comet 67P’s dark side. The image was taken by Rosetta's Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS).

When Rosetta arrived at the comet, its northern hemisphere was experiencing summer which lasted 5.5 years while southern hemisphere was undergoing totally dark, cold winters. The southern region received very small amount of sunlight for almost last five years and the only way this region of the comet could observed was MIRO, the Microwave Instrument for the Rosetta Orbiter. 

"We observed the 'dark side' of the comet with MIRO on many occasions after Rosetta's arrival at 67P/C-G, and these unique data are telling us something very intriguing about the material just below its surface," said Mathieu Choukroun from NASA's Jet Propulsion Laboratory (JPL), Pasadena, California, lead author of the study.

After analyzing this initial data, Choukroun and his colleagues suggested that there might be large amount of ice present within few tens of centimeters under the surface in the region.

"Surprisingly, the thermal and electrical properties around the comet's south pole are quite different than what is found elsewhere on the nucleus," said Choukroun. "It appears that either the surface material or the material that's a few tens of centimeters below it is extremely transparent, and could consist mostly of water ice or carbon-dioxide ice."

Scientists say that this difference could be result of the comet’s peculiar cycle of seasons. In the next coming months, the situation is expected to get a lot clearer since comet will reach perihelion, a point when it will be closest to the Sun along the orbit. As a result, the southern region will become bright and hot and provide an opportunity for more accurate measurements.

"We plan to revisit the MIRO data using an updated version of the shape model, to verify these early results and refine the interpretation of the measurements,” Choukroun said.

Rosetta is currently orbiting at 1,500 kilometers from the comet. It will soon get closer to the celestial object with the focus of comparing its two regions, northern and southern hemispheres with other instruments Rosetta. 

"First, we observed these dark regions with MIRO, the only instrument able to do so at the time, and we tried to interpret these unique data. Now, as these regions became warmer and brighter around perihelion, we can observe them with other instruments, too,” said Mark Hofstadter, MIRO principle investigator at JPL. 

We hope that, by combining data from all these instruments, we will be able to confirm whether or not the south pole had a different composition and whether or not it is changing seasonally."

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Hira Bashir covers daily affairs around the world.




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