Comets wear off as they are heaved through space by the forces of gravity from other space bodies, and now the characteristic jets emitted by comets as they approach the sun has been traced back to their origin on the comet surface. It appears as if sinkholes are the origin of several of the jets coming from the comet 67P/Churyumov-Gerasimenko.
By studying the high-resolution images from the ESA Rosetta spacecraft, which is orbiting the comet at a distance of 10-30 kilometers, the scientists have found 18 quasi-circular pits on the northern half of the comet, and some of these are really active spots.
While varying in size, from just a few tens of meters all the way up to some hundreds of meters in diameter, their depth can be as much as 210 meters below the surface. Jean-Baptiste Vincent from the Max Planck Institute for Solar System Research talks about the view they have of the comet pits, via Rosetta: “We see jets arising from the fractured areas of the walls inside the pits. These fractures mean that volatiles trapped under the surface can be warmed more easily and subsequently escape into space.” Vincent is also the lead author of the study, which was published in the journal Nature.
As the scientists go through and analyze the photos, captured by the OSIRIS camera, they believe that the pits have been formed starting out as as ceilings of several cavities below surface, which then became to thin to carry their own weight, eventually meaning they had to collapse, forming sinkholes. With sinkholes it’s easy to understand that the comet is quite fractured on the inside, and as they appear, any material located beneath the surface becomes the new target for erosion as time passes by.
Studying stones might never cease to be the fascination of many scientists, be those on Earth, the moon or those circulating the sun far out in the deep space. Yet, these tasks still carry with them the possibility for us to learn more about the origin of our solar system, and with that, the origin of life.