Those pictures, some of which are sharp enough to spot features 10 centimeters across, were taken by the European Space Agency’s Rosetta probe, which has been orbiting the comet (seen here in July from a distance of about 160 kilometers) for more than a year now.
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Comets are valuable assets for scientists studying the early solar system, since they are essentially frozen remains of the same rocks and dust that formed the system’s eight (or nine) planets.
The August 22, 2014 photo taken by the Navcam of the Rosetta space… They found that the layers on the larger lobe of the comet were 650 meters thick in some places, which wasn’t the case with the layers on the smaller lobe.
One of the main goals of the Rosetta mission is to measure in situ the volatile inventory of 67P, a Jupiter family comet. These co-centric strata suggest that the structure of the comet is similar to that of an onion. This suggests the lobes formed individually, each around their own center of mass.
Jay Melosh, a professor of planetary science at Purdue University who wasn’t involved in the study, told AP the discovery indicates that “the two lobes grew separately and only joined together later in their history, gently “docking” together during an ancient encounter that apparently did little damage to either partner”.
“I would say it’s a quite beautiful love story”, lead study author Matteo Massironi said.
Joseph Masiero, a Jet Propulsion Laboratory scientist who specializes in asteroids and comets and who was not involved in the study, said the argument is convincing.
However, questions remain. The paper does not address what processes helped these two bodies become one. Could these two objects simply have nudged each other and then stuck together? The cosmic fender bender may have happened less than 100 million years after the solar system formed.
Using data collected by the OSIRIS cameras onboard Rosetta, scientists were able to determine that the flat planes and arcs on 67P’s surface are in fact terraces that wrap around the two lobes like layers around an onion.
“I think gravity might not be the only holding agent”, he said.
The mission was conceived to unravel the mysteries of comets, which many scientists believe “seeded” early Earth with some of the ingredients for life.
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It seems more work will need to be done on that line of inquiry as well. “But how do you stick them together?”
