Rosetta's Comet is Weirder Than We Thought

Early results from Europe’s ongoing Rosetta comet mission show the icy body, believed to be a remnant from the formation of the solar system, is far more complex and diverse than scientists expected.

The first batch of science papers reveals details of Comet 67P/Churyumov-Gerasimenko, which is approaching the sun accompanied by the orbiting Rosetta spacecraft. After a 10-year journey, Rosetta put itself into orbit around Comet 67P in August and three months later released a lander to its surface.

So far, the most surprising finding is that analysis of the comet’s water shows it is chemically different from water in Earth’s oceans, challenging a long-held theory that crashing comets brought water to Earth and other planets in the inner solar system. That discovery was released in December, in advance of seven papers published in a special issue of this week’s Science.

The new studies show wide variation in where gases are being released from the comet’s twin-lobed, duck-shaped body. The information is important for understanding what processes the comet has been through and continues to undergo since its formation some 4.6 billion years ago.

Scientists believe comets are primordial bodies leftover from the solar system’s planet-forming days. The primary purpose of the Rosetta mission is to learn more about the birth of the solar system by studying the comet close up.

The Rosetta team is hoping to work out whether 67P originally was two bodies that melded together, forming the oddly shaped nucleus that exists today. The other option is the neck feature of the comet’s duck-shaped body was eaten away over time from what was a more symmetrically shaped, single structure

“We don’t know the answer to that yet,” astronomer Michael A’Hearn, with the University of Maryland, told Discovery News.

“If we see significant differences between the two lobes in composition – that are not just a seasonal effect – they we may be able to say something about how the pieces moved around when the comets were forming, how the larger components, the 100 meter-and-up pieces, came together to form a nucleus. That’s a rather open questions at the moment,” A’Hearn said.

Results from the first two months of Rosetta’s mission indicate the comet’s mass is roughly 100 million times the mass of the International Space Station, with a bulk density similar to cork, wood or aerogel, Science said in an overview of the newly published research.

That would mean that 67P’s nucleus has an internal structure that is fluffier and more porous than computer models previously predicted.

The new research shows the comet’s body is covered with organic materials, but not much surface ice. Scientists expected to see complex carbon-containing molecules such as alcohols and carboxylic acids. So far, however, the surface instead seems to be dominated by simpler hydrocarbons, a finding that may have implications for understanding how carbon-based molecules formed and spread through the solar system, one of the Science papers reports.

Read more at Discovery News