Boulders in Formation on Comet 67P/Churyumov-Gerasimenko

Scientists from the OSIRIS camera team for the European Space Agency’s Rosetta mission have released a rare image of the surface showing a most impressive site: a group of three icy boulders (one of which is about 30 meters/about 90 feet) across, standing upright on the rugged surface of the comet. The image (which was obtained last September and is only NOW being made public) shows these objects riding along on the comet at the rim of a small surface depression.  They appear to be only slightly attached to the comet itself.

Why these rocks are only tenuously attached is still something of a mystery, nor do the scientists completely understand how they formed. Somehow some sort of cometary activity causes surface boulders to move around on the surface. These aren’t the first boulder-type objects to be seen on the comet; earlier in the mission, scientists identified a rubble pile that was roughly the shape of a pyramid, and they nicknamed it “Cheops”).

Balanced rocks are nothing new on Earth. You may have seen them as you traveled around the American Southwest or Australia, or other places where erosion has cut into stone. Erosion forces include wind, water, and the action of glaciers.

The standing stones we know about on our planet are connected to the underlying rock by small “necks” of rock.  In the case of Comet 67P, there are a number of forces and activities at work that could be producing and moving these boulders around the surface.  There aren’t any good answers yet as to why and how these boulders exist, but the team intends to continue monitoring them as the mission proceeds.

The Rosetta mission is doing a long-term study of this comet, and will move along with it as Comet 67P rounds the Sun during its perihelion (closest approach) on August 13, 2015. Already, it has taught and shown us more about comets in a few months than years of Earth-based observations. As a former comet researcher, I find the mission to be a dream come true because we finally really get to truly “ride along” with a comet as it does its thing. Stay tuned—I’m sure there’ll be more great images coming out. If you want to follow along, surf over to the Rosetta mission site for the latest news.

Close-up of a Boulder Named Cheops 

The Rosetta mission keeps slowly cranking out good images of features on Comet 67P/Churyumov-Gerasimenko, the latest being this close-up of a 45-meter-long boulder on the surface of the comet. The blocky chunk was first spotted in images taken in August, but it has taken the OSIRIS imaging team at Max Planck Institute this long to release the high-resolution image, taken with their OSIRIS camera. The chunk reminded the scientists of an Egyptian pyramid, so they named it Cheops, after the famous Pharoah.

The comet has a lot of these boulders on its craggy, rugged surface, and they remain something of a challenge to understand. Nobody’s quite sure if these chunks are made of rock or ice, how they got there, and where they came from. Better images may solve some of the mysteries about this chunk and its icy parent body, and the next phase of imaging begins soon. I can’t wait to see them, and hope that they will release them as soon as they can. As a former comet researcher looking in, all I have to say is “Wow!  I want to see more!”

The Rosetta mission has been releasing lower-resolution NavCam images as the spacecraft orbits the comet, mapping its surface. I’ve been posting them and they’re all over the Web. In November, if all goes well, the control teams will send the Philae lander to settle down on the surface to take in situ (a fancy Latin term for “on site”) measurements and samples.

News from the mission continues to stream almost daily, but the image stream seems spotty at times. Many followers (comet observers, science writers, amateur and professional observers) have questioned the OSIRIS team’s slow pace of delivering much-touted high-resolution images.  One explanation for the slow stream is that there is a six-month “embargo” on releases to give scientists time to analyze the data and images. The world-wide community of observers  and others used to NASA’s fast release of Mars and images from Hubble Space Telescope, are challenging the Max Planck Institute to release images in a more timely manner — not six months from now when public interest is likely to have evaporated.

I understand the promises made to the camera scientists to let them get first crack at the images to do their scientists.  It lets them do their science without having to do do “instant science”. That’s pretty standard in most missions. However, most missions these days also have robust public outreach arms that allow for timely image releases that satisfy public appetites for cool science and also preserve a scientist’s right to do the science he/she was promised in return for devoting part of one’s career to building, testing, and flying an experiment. Indeed, the Rosetta mission folks at the European Space Agency have done a remarkable job of whipping up public interest in advance of the spacecraft’s arrival at the comet, and since then have worked to get out the lower-res images as they can.

To be fair, the process for getting and processing the images does take some time. You have to factor in the time it takes to actually get the images, and then transmit them back to Earth (which is not instantaneous) for quick analysis and processing. However, once they are ready, there should be nothing keeping the PR teams from selecting some good ones for release. This is where the NavCam images come from — and they have been delighting the public, and the many other scientists and amateur observers who are keenly interested in comets.

The seeming holdup for OSIRIS images comes (from what I understand) not from ESA, but from Max Planck Institute, which is a separate institution. Its scientists who worked on the camera are holding on to their rights to keep most of the images to themselves in order to get first crack at the science results.  They legally have six months before they have to make things public, and have (in the past) cited the fear that somebody somewhere might get an image, do some science on it, and scoop the team. It’s possible that could happen, but in all the years that NASA has been releasing spectacular images from spacecraft, it hasn’t happened. And, those missions that supply great images early on enjoy great public support (which is important the next time a scientist goes to apply for money for another spacecraft or experiment).

Regardless of where the images come from, the next few weeks are going to be blockbusters for the Rosetta mission. If you don’t have their web pages bookmarked, do it. And check in every day or so there and at the Max Planck Institute (linked above).  It’s not often you get fantastic images from the surface of a comet as it’s going around the Sun. This is an historic first!