Data and high resolution images from the European Space Agency's Rosetta spacecraft are revealing that the composition and surface features of Comet 67P/Churyumov-Gerasimenko are far more alien than anticipated.
According to Discovery News, the water on the comet is chemically different from that in Earth's oceans, a finding that challenges the theory that terrestrial water arrived via comets crashing into a younger Earth.
There is also a wide variation in how gases are being released from the rubber-duck-shaped comet, depending on day/night swings in its surface temperatures. Most of the outgassing is occurring at the comet's "neck," and scientists are investigating whether variations between the gasses being released by each of its lobes is evidence that the comet consists of two bodies that were melded together around the time the solar system was born.
It is also possible that the comet was originally symmetrical, but that its composition was such that the central area was eaten away more quickly than the remaining lobes.
"We don't know the answer to that yet," Michael A'Hearn, a University of Maryland astronomer 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.
As to the comet's composition, an article published in Thursday's Science argued that it is more porous than computer models predicted. It has the bulk density of cork, meaning that "this comet would float on a lake," according to Holger Sierks of the Max Planck Institute for Solar System Research.
The surface of the comet is covered in organic material, but instead of the complex carbon materials -- like alcohols and carboxylic acids -- that scientists expected to find, the majority of them are simple hydrocarbons.
But as Fabrizio Capaccioni, a planetary scientist at Italy’s National Astrophysics Institute, said, this is still "the first time we’ve seen such an abundance of organic material throughout [a comet’s] surface," and he and his team hope that further study will reveal the presence of carboxylic acids, one of the building blocks of amino acids.
Watch a video on Comet 67P/Churyumov-Gerasimenko via Discovery News below.
