Ammonia-Emitting Meteorite Hints At Life’s Origins

A meteorite that leaches ammonia is providing new fodder for the question of whether objects from space helped spark life on Earth (Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.1014961108). Ammonia contains the reduced form of nitrogen needed to participate in reactions that make the biomolecules essential for life, but researchers aren’t sure how ammonia may have originated on early Earth. Sandra Pizzarello of Arizona State University and colleagues turned up some unexpected ammonia when analyzing insoluble carbon-rich material from a meteorite found in Antarctica called Grave Nunataks 95229. The team added water to powder from the meteorite and subjected the material to high temperature and pressure, mimicking hydrothermal activity on Earth or on parent asteroids. Under those conditions, the meteorite gave off ammonia with a nitrogen isotopic signature distinct from that currently found on Earth, which the researchers say rules out contamination. A meteorite that fell to Earth’s surface might not have experienced high temperatures and pressures, but the experimental hydrothermal processing might have accelerated the meteorite’s intrinsic ammonia leaching, says biogeochemist Matthew A. Pasek of the University of South Florida. “Meteorites may indeed have served as life’s earliest fertilizers,” he adds.