There are places on comet 67P/Churyumov-Gerasimenko where cauliflowerlike textures look inward the dusty crust, similar goose bumps nether the skin. Scientists using the Rosetta spacecraft—which arrived at 67P inward August in addition to became the source mission to scope in addition to province on a comet—now intend they may accept discovered the source of these patterns on cliff faces in addition to inward deep pits: layer upon layer of rounded nodules, 1 to three meters across. These spherules, dubbed dinosaur eggs, could last the key edifice blocks that clumped together to cast the comet 4.5 billion years ago.
“These could last those fiddling cometesimals,” says Holger Sierks, primary investigator for Rosetta’s scientific discipline photographic television set camera in addition to a planetary scientist at the Max Planck Institute for Solar System Research inward Göttingen, Germany. Sierks presented the findings hither yesterday at a coming together of the American Geophysical Union.
In trying to sympathise how comets, asteroids, in addition to planets were built from microscopic pieces of dust whirling or in addition to thence the protoplanetary disk, modelers accept a employment they telephone band the “aggregation barrier.” It is relatively slow to larn small-scale pieces of dust to stick together, because of electrostatic forces in addition to van der Waals forces (tiny forces arising from the polarity of molecules). But in 1 lawsuit these clumps larn much bigger than a centimeter, high-speed collisions termination inward disintegrations rather than bigger clumps. So modelers accept had to come upwards up amongst ways to larn these centimeter-sized clumps to cluster together into the larger objects that eventually decease comets. There is some bear witness that small-scale clumps are the key edifice blocks: Many asteroids are made of chondrules, small-scale beads on the scale of a centimeter or less.
That’s 1 argue why Carey Lisse is in addition to thence surprised yesteryear the Rosetta observations. “I was hoping to consider marbles everywhere,” says Lisse, an astrophysicist at the Johns Hopkins University Applied Physics Laboratory inward Laurel, Maryland. “We’re getting non marbles but dinosaur eggs. They’re virtually a element of 10 to 100 bigger than predicted.” Lisse suggests that, upon closer inspection, the dinosaur eggs could really last composed of smaller marblelike units. Or perhaps, he says, formation models require to last adjusted to brand it easier for larger edifice blocks to grow inward the outer solar organization where comets cast in addition to where H2O ice in addition to organic molecules could assistance inward the sticking.
But some scientists are yet skeptical. Horst Uwe Keller, a planetary scientist at the Technical University of Braunschweig inward Germany, in addition to the one-time primary investigator for the Rosetta camera, says that it is every bit good early on to state whether the dinosaur eggs are really key edifice blocks. He notes that in that location are many deep pits on 67P where the texture is non found. And, he says, it is possible that the patterns could arise through some procedure of sublimation, inward which sunlight tin modify the comet surface yesteryear turning on jets of gas in addition to dust. “The images are real striking,” he says. “But nosotros don’t sympathise them.”