Rosetta Detects Exposed Water Ice on Comet 67P

Scientists have discovered exposed water ice on the surface of Comet 67P, also known as Churyumov-Gerasimenko.


The European Space Agency’s (ESA) comet-chasing Rosetta spacecraft arrived at Comet 67P in mid-2014. Since then, the orbiter has been studying the comet in great detail.

In a recent study, scientists used high-resolution images captured by Rosetta’s OSIRIS narrow-angle camera to determine that there are more than one hundred patches of water ice on the surface of Comet 67P.

This new study found 120 regions on the comet that are up to ten times brighter than an average comet’s surface. And all of these bright areas reside in areas with shadows, like at the base of cliffs, which minimizes the amount of solar energy these regions receive.


Although scientists can’t definitively say these bright patches are water ice, the evidence makes it the likely explanation.

“At the time of our observations, the comet was far enough from the Sun such that the rate at which water ice would sublimate would have been less than 1 mm per hour of incident solar energy,” explains the study’s lead author Antoine Pommerol. He continues, “By contrast, if carbon dioxide or carbon monoxide ice had been exposed, it would have rapidly sublimated when illuminated by the same amount of sunlight. Thus we would not expect to see that type of ice stable on the surface at this time.”

The team performed other experiments that lead them to believe what they have observed is water ice. And these researchers believe that further confirmation is coming soon.

Rosetta Detects Exposed Water Ice on Comet 67P - Clapway

Rosetta project scientist Matt Taylor details, “As the comet continues to approach perihelion, the increase in solar illumination onto the bright patches that were once in shadow should cause changes in their appearance, and we may expect to see new and even larger regions of exposed ice.”

The study was published in the journal Astronomy & Astrophysics.


Rosetta’s mission was only scheduled to run through December 2015. But the ESA announced on Tuesday, June 23 that the mission has been extended through September 2016.

With the extra time, Rosetta will attempt riskier research, like the collection of ejected dust samples, and ultimately, landing on Comet 67P. Rosetta delivered its Philae probe to the comet’s surface in 2014. Philae landed in an unfortunate, shadowed location, forcing the probe to enter hibernation mode just a couple days after landing. But Philae woke up on June 13. So, if Rosetta can stick its landing, the pair of comet researchers will be reunited.


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