The universe is teeming with complex organic molecules

Asteroids are less pure than comets, as they often withstand heating and the effects of liquid water. But these effects can produce exciting new organic complexity. For decades, scientists have known that meteorites called chondrites, which originate from asteroids, contain an amazing diversity of organic molecules. The Murchison meteorite, which fell in Australia in 1969, contains more than 96 different amino acids. Life uses only 20 or so. Osiris-Rex and Hayabusa 2 confirmed that the asteroids Bennu and Ryugu are as complex as those meteorites. At least some of this complexity appears to have arisen before the asteroids themselves: a Initial analysis Bennu’s sample indicates that it has preserved organic materials, including polycyclic aromatic hydrocarbons, from the protoplanetary disk.

Chemistry of life?

Organic molecules on the early Earth took a new and wonderful step in complexity. they They organized themselves somehow To something alive. Some hypotheses regarding the origins of life on Earth include an initial collection of organic materials from space. For example, the “PAH world” hypothesis posits a primordial soup phase that was dominated by polycyclic aromatic hydrocarbons. From this clay the first genetic molecules appeared.

More generally, understanding how complex organic materials form in space and end up on planets may give us a better idea of ​​whether life arose on other worlds as well. If the raw materials for life on Earth were formed in the interstellar medium, then the material for life should be everywhere in the universe.

For now, such ideas remain largely untestable. But because life itself represents a new level of organic complexity, astrobiologists are looking for complex organic materials as a potential biosignature, or sign of life, on other worlds in our solar system.

The European Space Agency’s Juice mission is already on track to study Jupiter and three of its icy moons, and NASA’s Europa Clipper mission blasted off toward one of those moons, Europa, in October. Both will use onboard instruments to search the atmosphere for organic molecules, as will a future Dragonfly mission to Saturn’s moon, Titan.

However, it is difficult to determine whether a particular molecule is organic or not Is the signature biometric or not?. If scientists can find complex enough organic molecular assemblies, that will be enough to convince at least some researchers that we have found life on another world. But as comets and asteroids reveal, the inanimate world is complex in its own right. Compounds believed to be biosignatures have been found on lifeless rocks, such as dimethyl sulfide that Haney’s team recently identified in 67P.