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Scientists from the Institute for Space Astrophysics and Planetology, for the first time, have found water ice on a comet's surface with the help of technology, on the European Space Agency's (ESA's) Rosetta orbiter. Even though they understood that molecules of water comprise most of the comet, or clouds of gas around the nucleus, the new discovery is a breakthrough in the detection of water ice.

"First, not finding ice was a surprise; now, finding it is a surprise," Murthy Gudipati, co-author of the paper, said in a press release. "It is exciting because now we are starting to understand the upper dynamic layers of the comet and how they evolved."

The water ice on the comet existed in two areas in the region called Imhotep, which was situated in the bottom of the main lobe.

The VIRTIS infrared instrument on the Rosetta picked up the water ice spectra signals just after the orbiter came on the ground on 67P in the late part of 2014. Being situated on cliff walls and debris falls, the ice was clearly visible.

"It looked like there was a breakage, or something fell down on the surface of the comet, and a large, new inside area that had water ice was exposed," Gudipati said. "Although we knew water ice had to be in the nucleus, this was our first direct detection of that interior ice."

The water ice grains were either tinier ones that were inside the micrometer range or bigger ones merely a few millimeters. Smaller grains were linked with the thinner frost layer while the bigger ones were sourced from the cooler lower surface.

"Keep in mind that comets are very porous, like cotton candy," Gudipati said. "Seventy percent of this comet is a void, and because of that, the heat from the surface does not go that deep."

Gudipati and his team are also investigating how the ice exposure altered even as the comet approached the sun.

"We knew water ice made up the majority of the comet, but we didn't know how deep or in what condition it was," he said. "This shows that it not very deep at all - perhaps just a few feet beneath the surface."

The findings were published in the Jan.13,2016 issue of Nature.