One of the precursors to DNA, adenine, and other prebiotic molecules, have been discovered in interstellar space by researchers at the National Science Foundation’s Green Bank Telescope (GBT) in West Virginia. The discovery of these molecules in the cold space between stars indicates that some of the precursors to life as we know it likely formed upon the dusty ice grains present there.
The discovery was made by researchers studying a large gas cloud located about 25,000 light-years from the Earth, towards the center of the Milky Way. The chemicals that were observed in the gas cloud included “a molecule thought to be a precursor to a key component of DNA and another that may have a role in the formation of the amino acid alanine.”
“One of the newly-discovered molecules, called cyanomethanimine, is one step in the process that chemists believe produces adenine, one of the four nucleobases that form the ‘rungs’ in the ladder-like structure of DNA. The other molecule, called ethanamine, is thought to play a role in forming alanine, one of the twenty amino acids in the genetic code.”
“Finding these molecules in an interstellar gas cloud means that important building blocks for DNA and amino acids can ‘seed’ newly-formed planets with the chemical precursors for life,” said Anthony Remijan, of the National Radio Astronomy Observatory (NRAO).
“In each case, the newly-discovered interstellar molecules are intermediate stages in multi-step chemical processes leading to the final biological molecule. Details of the processes remain unclear, but the discoveries give new insight on where these processes occur.”
It had been previously theorized by researchers that processes such as these occurred primarily “in the very tenuous gas between the stars.” But as these new discoveries suggest, “the chemical formation sequences for these molecules occurred not in gas, but on the surfaces of ice grains in interstellar space.”
“We need to do further experiments to better understand how these reactions work, but it could be that some of the first key steps toward biological chemicals occurred on tiny ice grains,” Remijan said.
The ability to identify these molecules was possible because of a “new technology that speeds the process of identifying the ‘fingerprints’ of cosmic chemicals. Each molecule has a specific set of rotational states that it can assume. When it changes from one state to another, a specific amount of energy is either emitted or absorbed, often as radio waves at specific frequencies that can be observed with the GBT.”
“New laboratory techniques have allowed astrochemists to measure the characteristic patterns of such radio frequencies for specific molecules. Armed with that information, they then can match that pattern with the data received by the telescope. Laboratories at the University of Virginia and the Harvard-Smithsonian Center for Astrophysics measured radio emission from cyanomethanimine and ethanamine, and the frequency patterns from those molecules then were matched to publicly-available data produced by a survey done with the GBT from 2008 to 2011.”
“This is a pretty special discovery and proves that early-career students can do remarkable research,” Pate said.
It’s an interesting discovery, and perhaps lends more credence to the possibility of panspermia, or even the possibility that simple life has, or regularly, develops in comets and asteroids.
There is also the interesting question of how different regions in the galaxy differ with regards to the organic molecules found, and how that relates to the emergence of possible life, and variations from what we know it to be.
Image Credits: Bill Saxton, NRAO/AUI/NSF