Comet Dust Discovered On Earth’s Surface For The First Time Ever
by Lisa Winter
Photo credit: Takaaki Noguchi
Though most recent excitement surrounding comets has been focused on Rosetta and her lander Philae becoming the first manmade object to do a controlled landing on the surface of a comet, a recent announcement has brought the thrill of comets a bit closer to home. A group of researchers discovered particles of comet dust embedded under the ice in Antarctica; the first time comet dust has ever been found on the surface of the planet. Takaaki Noguchi of Kyushu University is lead author of the paper, which was published in Earth and Planetary Science Letters.
Comet dust, more formally known as “chondritic porous interplanetary dust particles,” was assumed to be unable to survive on Earth’s surface because they’re extremely delicate and porous. Noguchi’s team discovered the particles after drilling 17 meters (58 feet) down into the ice. Not only that, but they were in exceptionally good shape.
These particles are normally retrieved for study by high-altitude planes with collection plates coated in silicon oil, which is sticky enough to trap the particles falling through the stratosphere. Unfortunately, using this oil contaminates the dust and needs to be cleaned off, prohibiting researchers from studying any organic attributes the dust may have. The dust found in the ice does not have that contamination and will allow researchers to do a more complete analysis of the particles.
Not only is the comet dust found in Antarctica cleaner than what is collected with planes, it is more plentiful. After several hours of the plane flying around, researchers are lucky to get a single speck of dust to study. This small availability of material limits the rate of experiments. On the other hand, melting snow and ice from two different sites yielded over 3,000 micrometeorites, 40 of which were deemed to be comet dust. This will give researchers much more freedom in the way they can study these particles, and could change the game for how they are collected.
A 2010 study from an unrelated group found evidence of comet pieces with an abnormally high carbon content, but this dust has been confirmed to have come from a comet and is more in line with what would be expected from a comet’s composition, based on results from NASA’s Stardust mission.
By analyzing comet dust—pristine and preserved dust, at that—researchers will be able to find clues about what comets may have brought to Earth while the planet was forming. Comets are commonly believed to have brought water and organic molecules that could have been the precursors to life, and these particles could help answer those questions. The particles discovered are some of the oldest cosmic samples available for study.