Water behavior on Comet 67P/C-G

Please consider donating to Behind the Black, by giving either a one-time contribution or a regular subscription, as outlined in the tip jar to the right. Your support will allow me to continue covering science and culture as I have for the past twenty years, independent and free from any outside influence.

A new paper based on accumulated data from Rosetta has given scientists a better understanding of the behavior of water ice on Comet 67P/C-G, including the process by which it escapes and is also covered by dust on the surface.

Although water vapour is the main gas seen flowing from comet 67P/Churyumov–Gerasimenko, the great majority of ice is believed to come from under the comet’s crust, and very few examples of exposed water ice have been found on the surface. However, a detailed analysis by Rosetta’s VIRTIS infrared instrument reveals the composition of the comet’s topmost layer: it is primarily coated in a dark, dry and organic-rich material but with a small amount of water ice mixed in.

In the latest study, which focuses on scans between September and November 2014, the team confirms that two areas several tens of metres across in the Imhotep region that appear as bright patches in visible light, do indeed include a significant amount of water ice. The ice is associated with cliff walls and debris falls, and was at an average temperature of about –120ºC at the time.

Note that many media sources today are falsely reporting the “discovery” of water by Rosetta on the comet. This is ridiculous, as water has been detected there for years. To suggest that “discovery” indicates a remarkable level of stupidity and ignorance by these news organizations about science. Either they think their readers are dumb, or they themselves don’t know anything.

Unfortunately, I worry that the answer is both.



  • steve mackelprang

    Hey! these are credentialed journalism majors… they not only know all this stuff cold, but also know what is best for general consumption

  • Edward

    Robert wrote: “Either they think their readers are dumb, or they themselves don’t know anything. Unfortunately, I worry that the answer is both.”

    I try to limit my technical news to only a few trusted sources. Too many editors and producers send their political analysts or newly graduated journalists to cover technical issues for which they have little or no background or previous knowledge. That is how we get questions about whether a black hole might have swallowed a missing airliner. Occam’s razor, folks. Start with the basics and pay attention.

    I once worked for a scientist who was interviewed for the local evening news. We received a copy of the unedited interview and many of us in the lab watched it. The reporter had him tell her the whole story in his own words, and when he finished a few minutes later, she asked him to tell it again more briefly. A minute or so later she had him do it a third time even more briefly, and when he missed an important step she mentioned it for him as a quick correction, and he finished the summation in only a quarter minute, or so. That was the version that aired.

    I was impressed that she had understood that the missed step was important to understanding the story and the technology. She was not a technology reporter, and probably did not know anything about the topic, but she knew how to interview.

    The same scientist was talking to some of his non-scientist friends about the plasma in the sun’s corona. One of his friends asked how blood gets to the sun, and he realized that most people learn the word “plasma” from TV medical shows and don’t know that the word also means a gas that is so hot that it is no longer a gas — a fourth phase of matter.

Leave a Reply

Your email address will not be published. Required fields are marked *