Víctor Rivilla and his colleagues at the Spanish Astrobiology Centre in Madrid have made an astounding detection. The team spotted a vital component of the simplest phospholipid in space. If you aren't aware, phospholipids are molecules that comprise the membranes of all cells on Earth. In a pre-print that hasn't been peer-reviewed, the team explains their discovery of the phospholipid component, known as ethanolamine, and note that this finding indicates that all of the precursors for life could have originated in space.
Science is yet to provide full disclosure on the origin of life, but we do know a few things. We know that life started on Earth about 4.5 billion years ago and involved innumerable molecular components. One theory explains that these components were available on Earth because the planet was seeded from space with the building blocks needed for life — that space is filled with gas and dust that contain all the organic molecules necessary for life.
Astronomers have observed and recorded these building blocks, which comprise amino acids, the precursors of proteins, and molecules that can store information in the form of DNA. But, there exists another pivotal component for life — molecules that can form membranes capable of encapsulating and protecting the molecules of life in compartments called protocells. Phospholipids have never been observed in space. Until Rivilla and his team's discovery.
The origin of life on earth and other planets
The group analysed light from an interstellar cloud of gas and dust called Sagittarius B2, just 390 light-years from the center of the Milky Way. Ethanolamine has the chemical formula NH2CH2CH2OH. The team simulated the spectrum that this molecule ought to produce at the cold temperatures thought to exist in the cloud. They then looked for, and found, clear evidence of this spectrum in light that had passed through the cloud. "This has important implications not only for theories of the origin of life on Earth but also on other habitable planets and satellites anywhere in the Universe," said the team.
Previously, astronomers have found ethanolamine in meteorites. Researchers are still unaware how it got there, with some arguing that it was solely formed through a bizarre set of reactions on a parent asteroid.
However, according to the latest discovery, ethanolamine is much more pervasive.
The secrecy never ends
On Earth, ethanolamine forms the hydrophilic head of phospholipid molecules that self-assemble into cell membranes. Rivilla and colleagues told Astronomy Magazine its discovery in interstellar clouds suggests “ethanolamine could have been transferred from the proto-Solar nebula to planetesimals and minor bodies of the Solar System, and thereafter to our planet.” That, in turn, could have led to the formation of cells in the prebiotic soup from which our earliest ancestors emerged.
Another radical idea is that ethanolamine might allow the formation of protocells in the interstellar medium itself. The interstellar medium is rich in other prebiotic components, such as water and amino acids. The result would then be ready-made melting pots of prebiotic goop ready to seed the Earth or any other body that passes by.
Though none of these answers the question of how life began on Earth, the work is an indication that there is no longer any mystery about where the building blocks of life might have come from. “These results indicate that ethanolamine forms efficiently in space and, if delivered onto early Earth, it could have contributed to the assembling and early evolution of primitive membranes", said Rivilla and the team. That said, what happened next is still shrouded in secrecy.