One nitrogen atom, three hydrogen atoms. That’s all it takes to make the basic ammonia molecule. This simple compound was one of the most important building blocks for the origin of life, scientists believe, providing the nitrogen that is crucial to many organic compounds. They just don’t know for sure how so much of it could form under the conditions of the early Earth.
In a new study this week, Sandra Pizzarello and colleagues tie the ammonia surplus to one of the more fascinating theories about the rise of life—that some of its basic components seeded the Earth from space on board meteorites that pounded the planet’s surface.
Pizzarello’s team analyzed a particular meteorite found in Antarctica. Its name is Graves Nunataks (GRA) 95229, and it was discovered in 1995. But its important characteristic is that the it belongs to a class of meteorites called carbonaceous chondrites that are full of organic materials. In the lab, the researchers tried to simulate how those materials in GRA 95299 might have reacted when they reached the younger Earth.
Pizzarello and her co-authors subjected a sample of the meteorite … to temperatures of 300 degrees Celsius at high pressures in the presence of water to simulate hydrothermal conditions on the meteorite’s parent asteroid or on Earth. Under heat and pressure, GRA 95229 released almost nothing but ammonia, in amounts that constitute roughly 1 percent by mass of the type of meteoritic material examined. Its parent asteroid, the authors speculate, must have been rich in ammonia. [Scientific American]