This animation comprises 101 images acquired by the Navigation Camera on board ESA’s Rosetta spacecraft as it approached comet 67P/C-G in August 2014. The first image was taken on 1 August at 11:07 UTC at a distance of 832 km. The last image was taken 6 August at 06:07 UTC at a distance of 110 km. ((c) ESA/Rosetta/Navcam)
Back on Aug. 6 the European Space Agency‘s unmanned space probe Rosetta completed its decade long journey across space to meet up with its target, Comet 67P/Churyumov–Gerasimenko, making it the first spacecraft to rendezvous with a comet.
As the spacecraft neared its target, it took some close-up photos of the comet with its two camera Navigation Camera system (NAVCAM).
After examining the images, members of the Rosetta team at ESA couldn’t help but notice that Comet 67P/C-G appeared to be a very oddly shaped object. Its peculiar shape led them to nickname the comet the “rubber duck”.
As they continue to study Comet 67P/C-G, the scientists are looking to get a better understanding of its surface properties.
Mark McCaughrean, ESA’s Senior Science Advisor thinks that there should be a number of craters on the comet’s surface. If so, scientists would like to know how they were formed. Are they impact craters from being hit by various objects or could they be the result of residue left by materials that burst out from inside the comet?
Rosetta is now traveling in front of the comet at an average speed of about one meter per second said McCaughrean.
The spacecraft is now only about 50 kilometers away from Comet 67P/C-G, which is about 450,000,000 kilometers from the sun.
The Rosetta team is planning to place the spacecraft in orbit around the comet in a couple of weeks where it’ll stay for the remainder of its planned mission.
McCaughrean said that once Rosetta is in orbit it will do so at an average distance of about 30 kilometers.
Artist impression of ESA’s Rosetta approaching comet 67P/Churyumov-Gerasimenko. ((c) Spacecraft- ESA/ATG Medialab/Comet – ESA/Rosetta/NAVCAM
The team is planning to occasionally lower the spacecraft’s orbit to about 10 kilometers above the comet’s surface or possibly even lower when the Rosetta’s attached Philae lander is deployed in November.
But before deciding to drop Rosetta to a lower altitude McCaughrean said that the team will need to consider the comet’s activity, such as how much gas and dust is flowing way from it.
Along with getting the spacecraft ready to orbit the comet, scientists have been quite busy trying to find an ideal landing spot for the Philae lander.
They have selected a number of possible landing sites and ESA is expected to announce the primary and back-up landing sites on September 15.
McCaughrean described the ideal landing site for Philae as one that would be about one square kilometer in size and able to provide enough sunlight to charge the probe’s battery.
Since the comet’s gravity is so low, the probe will most likely bounce when it first touches down, so ESA engineers have equipped it with two harpoons and some ice screws to keep the probe steady and attached to 67P/C-G’s surface.
While the Rosetta spacecraft is the mission’s most powerful machine and will be doing most of the work, the Philae lander, since it will actually be on the surface of the comet, will be able to do things that Rosetta can’t.
Artist’s impression of Rosetta’s lander Philae on the surface of comet 67P/Churyumov-Gerasimenko. Philae will be deployed to the comet in November 2014. ((c) ESA/ATG Medialab)
One of the first tasks assigned to Philae is to take a 360° panorama of its location.
It will use its onboard microscopes to get a closer look at the surface. Then it will drill about 25 centimeters into the comet to pull material up for analysis by Philae’s small laboratory so scientists can learn more about what makes up Comet 67P/C-G.
“We’re learning a huge amount (about the comet), but there’s still a huge amount to be learned in the next four years we sit next to this comet as it evolves,” said McCaughrean.
You can listen to the Science World radio interview with Mark McCaughrean either through the player below or check out the entire show at the times and places listed in the right side column.
Very Interesting article and interview! Just for clarification however, I believe that the scientist (toward the end of interview) said that Rosetta would learn much more over the next ‘full year’ (not four years) as the comet evolves.
Looking at it ‘geologically’ as it rotates, the three segments of the comet appear to be limited by four parallel planes. If the comet were sitting in Antarctica one would say it had broken off the Antarctic ice sheet which is a layered entity. The dimensions of the comet just happen to be around the thickness of the Antarctic ice sheet at 4 to 5 km. This is not to say it came from Antarctica but may be it could come from an asteroid impact with a planetary or lunar ice sheet somewhere in the solar system. The gas content of any ‘air’ bubbles in the comet’s ice would be of considerable interest in this case.