Another Rosetta first! Water ice found on the surface of comet 67P

L A Times ^ | 01/13/2016 | Deborah Netburn•

[BenLurkin]

The finding, published Wednesday in Nature, solves a long-standing mystery about water ice in comets. Scientists already knew that the coma... is dominated by water molecules....

"It is exciting because now we are starting to understand the upper dynamic layers of the comet and how they evolved."

The surface of comet 67P, like most comets, is primarily covered by dark organic materials that appear almost black. That's because as comets fly toward the sun, they are exposed to warm temperatures that cause volatiles like water ice on their surface to sublimate - or go directly from solid to gas.

What remains on the crust are what are known as refractory materials. These include silicates similar to rocks, sand and dirt on Earth and carbonaceous materials. Because these materials do not sublimate, the comet's surface becomes increasingly organic and silicate rich over time, said Michael Combi, who studies comets at the University of Michigan and coauthored the paper.

The surface water ice on comet 67P Churyumov-Gerasimenko was discovered in two places several tens of feet across in a region known as Imhotep, on the bottom part of the main lobe of the comet. It was found using the VIRTIS infrared instrument, which scanned the area looking for water ice spectra signals not long after the Rosetta orbiter caught up with 67P in the fall of 2014.

In both cases the ice appeared on cliff walls and debris falls, and appeared as noticeably bright patches in visible light.

"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."

[soycd]

The biggest surprise would be a comet without H2O.

[RetiredTexasVet]

“It is exciting because now we are starting to understand the upper dynamic layers of the comet and how they evolved.”

I’m sure many lives on earth will be immeasurably improved by this “exciting discovery”!

[mkmensinger]

Water Ice?

[Don W]

You called?

[Pete from Shawnee Mission]

OK, so we have a giant comet glacier plowing through space, full of ice, debris, and dust that it has gathered in its million year sojourn in the Oort cloud. As it approaches the sun, perhaps on multiple passes, the ice sublimates away leaving a surface crust of dust and aggregate. Eventually, the water underneath the crust is gone leaving a loose consolidation of material. If there is enough mass and gravity, it holds together. If it comes close enough to the sun the heat may fuse or partly fuse the material and it becomes a small planetary body. If not, it may continue around the sun like the shot from a 12 gauge, dispersing with time and distance, and become a regular meteor shower...

Nifty!

[Jack Hydrazine]

Why did it take so long to find water? Astronomers for the longest time have told the public that comets are essentially dirty snowballs just full of water!

Guess they have to re-write the text books.