Comets R Us
After analyzing the dust particles of a variety of comets with NASA's Spitzer Space Telescope, the Deep Impact spacecraft and the internationally funded Infrared Space Observatory, Dr. Carey Lisse, of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., suspects that the answer is yes.
"Comets are the stepping stones to planets," said Lisse. "With these missions, astronomers know more about comets today than ever before, and we're still only beginning to scratch the surface."
He presented his findings at the 38th meeting of the Division for Planetary Sciences of the American Astronomical Society in Pasadena, Calif.
According to Lisse, the Deep Impact mission, which sent an 820-pound impactor into the path of a hurtling comet about 5 by 8 kilometers (3 by 5 miles) wide, provided a "Rosetta stone" for studying solar system formation in the universe. The collision, on July 4, 2005, unleashed a plethora of pristine particles that had been locked in the core of comet Tempel 1 since the dawn of our solar system.
From its lofty perch in space, Spitzer was in the perfect position to scrutinize the cometary material ejected from comet Tempel 1. The sensitive telescope's spectrometer instrument detected dust particles finer than human hair, and discovered the presence of silicates (crushed rock or sand), carbonates (chalk), smectite (clay), metal sulfides (like fool's gold), amorphous carbon (soot) and polycyclic aromatic hydrocarbons (carbon-rich molecules found on barbecue grills and in automobile exhaust on Earth).
Scientists have determined that comet Tempel 1 is a loosely assembled icy dirtball with the consistency of talcum powder. "The impactor was able to go 20 to 30 meters into the comet and release material that hadn't been baked or boiled by the comet's previous trips around the sun," said Lisse.
Lisse and his team later compared their Tempel 1 data to observations of comet Hale Bopp made by the Infrared Space Observatory in 1997. Although Hale Bopp did not show any of the iron-rich olivine silicates found in Tempel 1, team members did find many chemical similarities, like ice made of water, carbonates, sulfides, polycyclic aromatic hydrocarbons and other types of silicates.