Large patches of water ice found on the surface of comet 67P

A team of scientists has, for the first time, exposed water ice on the surface of comet 67P. The discovery, made by instruments aboard European Space Agency's Rosetta orbiter, is expected to solve the age-old mystery surrounding water ice on comets.

So far, the scientists were aware about the presence of water ice in the nucleus of the comet. In addition, the fact that water ice is contained in the expanding cloud of gas surrounding the comet's nucleus was known as well. However, until now, the researchers were unable to detect its presence on the outer surface of the comet.

"First, not finding ice was a surprise; now, finding it is a surprise," said Murthy Gudipati, a planetary scientist at the Jet Propulsion Laboratory in California, reports Phys.org. "It is exciting because now we are starting to understand the upper dynamic layers of the comet and how they evolved."

The large grains of water ice have been recovered from two different locations on the surface of the comet Comet 67P/Churyumov-Gerasimenko. The Rosetta orbiter has been quite instrumental in reporting its findings since it started to orbit the comet in August 2014.

The researchers suspect that these big patches of water ice might have formed on the surface of the comet as a result of the heat from the sun that vapourised the water ice buried below the surface, a process called sublimation. The vapours might have then recondensed to and redeposited back on the surface, without ever leaving comet 67P, reports Space.com.

The researchers further say that the water ice found on the surface of the comet did not vapourize into space quickly because of its association with recent debris falls and cliff walls. The solar illumination was found to be negligible in the area where the two large patches were observed.

The complete findings have been reported in the journal Nature.