Building Blocks of Ancient Comets Discovered in Meteorite
A meteorite discovered on the La Paz Icefield in Antarctica held onto a deep secret — a sample of carbon left over from the formation of the oldest comets in the Solar System. Analysis of this carbon-rich (C-rich) sample from the earliest age of the Solar System revealed a makeup and structure similar to primitive comets found in the Kuiper Belt, orbiting in the distant reaches of our family of planets.
LaPaz Icefield 02342, like other meteorites, are remnants of asteroids which survived journeys through the Earth’s atmosphere, before being recovered on the ground. Asteroids, like comets, coalesced from the gas and dust which formed the Solar System. However, asteroids formed much closer to the Sun than comets, resulting in a lower concentration of water ice and carbon in their bodies.
“Asteroids are believed to grow by accretion, where dust particles grow into dust clumps that grow into bigger clumps that grow into rocks etc., eventually building up into much larger objects. This C-rich object probably didn’t land on a fully formed body, but rather probably accreted into a much smaller clump of material that eventually became part of the meteorite’s parent asteroid,” explained Dr. Larry Nittler of The Carnegie Institution for Science, in an exclusive interview with The Cosmic Companion.
