The universe is full of complex organic molecules

Asteroids are less pure than comets, often enduring heat and liquid water. But these effects can create dramatic new organic complexity. For decades, scientists have known that meteorites from asteroids, called chondrites, contain a surprising variety of organic molecules. The Murchison meteorite, which fell in Australia in 1969, contained more than 96 different amino acids. Life just takes more than 20 uses. Osiris-Rex and Hayabusa2 confirmed that the asteroids Bennu and Ryugu are as complex as those meteorites. And at least some of this complexity predates the asteroids themselves: A preliminary analysis The Bennu sample suggests that it retains organic material from the protoplanetary disk, including polycyclic aromatic hydrocarbons.

The Chemistry of Life?

Organic molecules on the early Earth took a remarkable new step in complexity. They are somehow they organized themselves to a living thing. Some hypotheses about the origin of life on Earth involve a starting set of organic material from space. For example, the “PAH world” hypothesis assumes an initial soup phase dominated by polycyclic aromatic hydrocarbons. The first genetic molecules appeared from this ointment.

In general, understanding how complex organic matter forms in space and ends up on planets can give us a better idea of ​​whether life could have originated on other worlds. If the raw materials for life on Earth originated in the interstellar medium, then the ingredients for life must be everywhere in the universe.

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

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

However, it is difficult to determine whether a particular organic molecule is present biosignature or not. If scientists were to find complex enough organic molecular compounds, it would 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 itself is complex. Compounds thought to be biosignatures have been found in nonliving rocks, such as dimethyl sulfide, which Hänni’s team recently identified in 67P.