Planetary scientists have found a wide range of molecules that are crucial for life among a lot of other organic substances present in asteroids, meteors, and even interstellar space. Now, scientists report new insights into asteroid Bennu, which was sampled by the NASA mission OSIRIS-REx. The latest research suggests tentative evidence for a substance we have not encountered before in extraterrestrial material.
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When it comes to molecules fundamental to life, we usually focus on the nucleotide bases: adenine, cytosine, guanine, thymine, and uracil, which are the fundamental units of DNA and RNA. There are also amino acids, which are the building blocks of proteins. Although over 500 are known, only 22 are used by known life. Of those 22, only 14 have been found in stuff from outer space – until now, possibly.
The new work confirms the presence in the sample of all five nucleobases and of the 14 amino acids that were already found by others. They also report tentative detections of tryptophan, a pretty important amino acid. This molecule is the precursor of the neurotransmitter and “happiness molecule” serotonin, of the hormone melatonin, which regulates the sleep cycle, and the vitamin B3. A form of vitamin B3 has previously been detected in the Bennu sample, which gives credence to this new detection.
Still, the team is looking into other ways to check the Bennu material to confirm the presence of tryptophan without doubt. Tryptophan is pretty fragile, so it is not a big surprise that it has not been found before in meteorites. The delicate collection of 121.6 grams (4.3 ounces) of material by OSIRIS-REx might have kept this and other dainty molecules safe.
“Our findings expand the evidence that prebiotic organic molecules can form within primitive accreting planetary bodies and could have been delivered via impacts to the early Earth and other Solar System bodies, potentially contributing to the origins of life,” the authors wrote in the paper.
OSIRIS-REx dropped a capsule with the sample in the Utah desert after over two years orbiting the 500-meter (1,630-foot) wide Bennu, which is currently the number one most dangerous asteroid, as it has a 1-in-1,750 chance of hitting our planet between 2178 and 2290. The date of greater risk is September 24, 2182. Coincidentally, the sample came back to Earth on September 24, 2023.
The study is published in the Proceedings of the National Academy of Sciences.
[H/T: ScienceAlert]
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