Two critical DNA and RNA components have been found in this rock, a 2-gram fragment of the 1969 meteorite that crashed in Murchison, Australia, for the first time ever found in an extraterrestrial source, according to researchers.

The finding adds to the body of evidence suggesting life originated in space.

Additional components necessary for life have been discovered in meteorites.

According to research published in Nature Communications on April 26, the five bases that store information in DNA and RNA are present in space rocks that have fallen to Earth within the last century.

The genetic code of all life on Earth is made up of these “nucleobases”—adenine, guanine, cytosine, thymine, and uracil—along with sugars and phosphates. It is still unknown if these essential components for life were initially produced on Earth or whether they originated in space (SN: 9/24/20). The discovery, however, the researchers argue, adds to the body of evidence that points to the beginning of life in space.

Since the 1960s, researchers have found fragments of adenine, guanine, and other chemical molecules in meteorites (SN: 8/10/11, SN: 12/4/20). Uracil has also shown some signs, but up until now, cytosine and thymine have eluded researchers.

Astrochemist Daniel Glavin of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, claims that all the bases found in DNA and RNA as well as life on Earth have been identified, and they are also present in meteorites.

A few years ago, geochemist Yasuhiro Oba of Hokkaido University in Sapporo, Japan, and associates developed a method for delicately extracting, separating, and analyzing several chemical components in liquified meteorite dust.

In comparison to other investigations, “our detection method has orders of magnitude more sensitivity,” claims Oba. A similar method was employed three years earlier by the researchers to find ribose, a sugar required for life, in three meteorites (SN: 11/22/19).

One of those three meteorite samples, as well as three additional ones, were examined in the latest work by Oba and colleagues in collaboration with astrochemists from NASA in search of nucleobases, another sort of essential component for life.

The researchers believe that by using cold water instead of the traditional acid in their softer extraction method, the chemicals are preserved. We’re discovering that this extraction method is highly suitable for these delicate nucleobases, adds Glavin. “Instead of preparing hot tea, it’s more like a cold brew.”

Using this method, Glavin, Oba, and their colleagues examined four samples of meteorites that originated in Australia, Kentucky, and British Columbia decades ago to determine the abundances of bases and other chemicals important to life. Adenine, guanine, cytosine, uracil, and thymine, various molecules connected to those bases, and a few amino acids were found and quantified in all four.

The scientists also analyzed chemical abundances in soil taken from the Australia location using the same method, and then they compared those results to the measured meteorite levels. The meteorite values exceeded those of the surrounding soil for some compounds that were found, indicating that these substances may have entered Earth’s atmosphere via these rocks.

Nevertheless, the soil abundances for some chemicals, such as cytosine and uracil, are up to 20 times higher than in the meteorites. According to cosmochemist Michael Callahan of Boise State University in Idaho, this could indicate contamination from the earth.

Callahan believes that the researchers correctly identified these chemicals. They “didn’t present enough convincing data to persuade me that they’re actually extraterrestrial,” nevertheless. Callahan previously worked for NASA, where she measured organic compounds in meteorites alongside Glavin and other researchers.

Yet, Glavin and his associates cite a few particular compounds that were found to back up the idea of an extraterrestrial origin. According to Glavin, the researchers measured more than a dozen other chemicals connected to life, including isomers of the nucleobases. Isomers and the bases they are connected with have identical chemical structures, but their constituent parts are arranged differently. Several of those isomers were discovered by the team in the meteorites but not in the soil. “We should have found those isomers in the soil as well if there had been contamination from the earth. And we failed to,” he claims.

Direct contact with pure asteroids, the origin of such meteorites, might provide the solution. The asteroid Ryugu, which Japan’s Hayabusa2 mission brought to Earth in late 2020, has already been subject to Oba and colleagues’ extraction procedure (SN: 12/7/20). Similar samples from the asteroid Bennu are anticipated to be returned by NASA’s OSIRIS-REx mission in September 2023 (SN: 1/15/19).

“We’re quite interested in the narratives that resources have to offer,” says Glavin.