The Universe Is Teeming With Complex Organic Molecules

Asteroids are less primitive than comets, often exposed to heat and liquid water. But these effects can create dramatic new biological complications. For decades, scientists have known that meteorites called chondrites, which originate from asteroids, contain an astonishing variety of organic molecules. The Murchison meteorite that fell in Australia in 1969 contained over 96 different amino acids. Life only uses 20 or so. Osiris-Rex and Hayabusa 2 confirmed that asteroids Bennu and Ryugu are as complex as those meteorites. And at least some of this complexity seems to have originated before asteroids: A Preliminary analysis The Bennu sample suggests that it retains organic material, including polycyclic aromatic hydrocarbons, from the protoplanetary disk.

The chemistry of life?

Organic molecules on the early Earth took a new, extraordinary step in complexity. they are Organized themselves somehow Some hypotheses for the origin of life on Earth in living things involve a starter kit of organic matter from space. For example, the “PAH world” hypothesis posits a stage of primordial soup that was dominated by polycyclic aromatic hydrocarbons. From this slurry the first genetic molecules emerge.

In general, understanding how complex organic matter forms in space and ends up on planets can give us a better idea of ​​whether life originated on other worlds. If the raw material for life on Earth is formed in interstellar medium, then the universe should contain life elements everywhere.

For now, such ideas remain largely unsettled. But because life itself represents a new level of biological complexity, astronomers are looking for complex organic materials as possible biosignatures, or signs of life, on other worlds in our solar system.

The European Space Agency’s JUICE mission is already on its way to study Jupiter and its three icy moons, and NASA’s Europa Clipper mission headed for one of those moons, Europa, in October. Both will use spacecraft instruments to search the atmosphere for organic molecules, as will future Dragonfly missions to Saturn’s moon, Titan.

Yet it is difficult to determine whether a given organic molecule is A biosignature or not. If scientists find enough complex organic molecular assemblies, it will be enough to convince at least some researchers that we have life on another planet. But as comets and asteroids reveal, the nonliving world is complex in its own right. Compounds thought to be biosignatures have been found in lifeless rocks, such as dimethyl sulfide Haney’s team recently detected in 67P.