Deep space molecule may help explain origins of life

A special type of molecule discovered deep in space may point to why life developed as it did on Earth.

Simple molecules existing around the galactic center show off a spectrum of light that makes them possible clues in the mystery of how life developed on Earth.

The Washington Post explains that molecules found on Earth can be chiral, which means they are right- or left-handed.  Whether such molecules are oriented in a right- or left-handed way deeply impacts their function.  Almost all life forms rely on left-handed molecules, but scientists are unsure as to why or how the trend got started.

“You could just as easily imagine us building things out of right-handed molecules,” Brandon Carroll of the California Institute of Technology said. “So asking how and why we settled on what we did is one of the biggest unanswered questions in biology.”

The advantage to skewing in one direction or another with chiral molecules is that more complex forms can be produced when every molecule of one type is facing the same way.  DNA, for example, owes its shape to coordinated chiral molecules.

A team of researchers have now found the first example of a chiral molecule residing in deep space. The team used data from the Green Bank Telescope Prebiotic Interstellar Molecular Survey (PRIMOS) to observe evidence of the chiral molecule propylene oxide (CH3CHOCH2) in a huge star-forming cloud called Sagittarius B2.

The molecules were detected by observation of which wavelengths of radio light were reflected or absorbed.  Each type of molecule has a distinct set of frequencies, and the radio light detected in the cosmic cloud could only have been produced by propylene oxide.

Future study will hopefully determine whether the propylene oxide in Sagittarius B2 is mostly right- or left-handed.  Finding a bias towards left-handed molecules would make an intriguing case for Earth’s life originating from molecules of interstellar gas and dust.

“One plausible theory is that a small excess of left-handed molecules was produced in interstellar space before our solar system was formed, and biochemical processes on the young Earth amplified that initial interstellar excess,” Ben McCall of the University of Illinois said.  “This theory can only be tested by observing chiral molecules in space, and this work sets the stage for such tests.”

Understanding more about the handedness of different types of chiral molecules in the universe could reveal how unique Earth may or may not be when it comes to the development of life.

“Ideally, we should strive to detect other chiral species, especially those of interest in biology or found in meteorites,” Stefanie Milam of NASA said.  “This is a very exciting discovery for astrobiology.”

The study was accepted for publication in the journal Science.