For the first time, scientists have discovered a special type of asymmetric molecule in space, a discovery that they say could be key to understanding the origins of life on Earth.
The newly discovered molecule is called propylene oxide. It was discovered in a cloud of gas and dust near the center of the Milky Way called Sagittarius B2.
The molecule’s most striking feature is its chirality, or “handedness,” meaning that the molecule has two possible mirroring branches, a “right hand” and a “left hand.”
"This is the first molecule detected in interstellar space that has the property of chirality,” said Brett McGuire, the Jansky Postdoctoral Fellow at the National Radio Astronomy Observatory, in a statement, “making it a pioneering leap forward in our understanding of how prebiotic molecules are made in the Universe and the effects they may have on the origins of life."
Scientists have been aware of molecules with chirality within our own solar system for some time, but this is the first time scientists have detected them in interstellar space.
Now that they have discovered the molecule, researchers say that they will be able to perform more complex tests.
First up: A test to determine which “hand” the propylene oxide favors. Currently, scientists are unable to determine which hand the molecule would rather shake with, but in the future, they intend to test the molecule's reaction to polarized light.
The different hands of chiral molecules are mirror images, but not interchangeable, scientists say. Propylene oxide comes in both “left handed” and “right handed” varieties, each of which forms chemical reactions with only other molecules that have the correct “handedness.”
"When you shake somebody's hand, your right hand shakes another right hand, and it forms that nice, interlocking gesture; if you try to shake a left hand with your right hand it's a little awkward because the interaction is different," Dr. McGuire told Space.com. "Chiral molecules work the same way.”
For this reason, many of Earth’s chiral molecules (such as amino acids) are all the same “handedness.”
Scientists say that this discovery opens the door for further research on the origins of life.
Brandon Carroll of the California Institute of Technology, one of study’s authors, said that while scientists have seen preferences towards one “handedness” or the other on meteorites in our solar system, it is important to understand the origin of those preferences.
And to do that, he says, scientists must understand the gas clouds, like Sagittarius B2, where meteorites are formed.
If chiral molecules exist in the gas clouds that form meteorites, as propylene oxide exists in Sagittarius B2, and they have pre-existing “handedness” preferences, then that could explain why chiral molecules on Earth have these preferences, too.
This finding could be further proof of the theory that the so-called building blocks of life were delivered to Earth by meteorites.
In May, researchers took another step towards proving this theory when they discovered an amino acid called glycine on a comet.
Speculating about the origin of differently oriented chiral molecules can be dangerous. What would our world be like if amino acids had been differently "handed" when they arrived via meteorite? In 2012, one prominent chemist made waves by speculating that different chiralities may have produced smarter dinosaurs.
Whatever the possible past could have been, scientists like McGuire are keen to explore, saying that, “By discovering a chiral molecule in space, we finally have a way to study where and how these molecules form before they find their way into meteorites and comets, and to understand the role they play in the origins of homochirality and life.”