Furukawa and 13 co-authors reported that deliveries of organic molecules from space, such as those found in carbonaceous meteorites, have long been hypothesized as a source of the inventory of the first life on Earth. This hypothesis is strengthened by detections of two of life’s fundamental building blocks—nucleobases and protein-building amino acids—in pristine samples returned by spacecraft from the carbonaceous asteroids Bennu and Ryugu.
The caption for the above graphic is as follows:
a, Multiple reaction monitoring (MRM) chromatograms of derivatized pentose fragments in the Bennu extract using a DB-17ms column.
b, MRM chromatograms of derivatized pentose standards.
c, MRM chromatograms of SiO2 blank.
d, Fragmentation of electron ionization (EI) of derivatized ribose (ribononitrile tetraacetate).
e, EI fragment spectrum of derivatized ribose. Collision-induced dissociations of the EI fragments are shown in Extended Data Fig. 2.
Only the presence of peaks for all five transitions with consistent intensity ratios to standards leads to a confident detection. The additional peaks observed are derived from co-eluting compounds. The co-eluting compounds least influenced the mass transition of m/z 242 to 140. Signal Int., signal intensity; STD, standard.
However, life also requires sugars, which cannot be searched for in Ryugu samples due to limited available mass, and their presence in some meteorites is equivocal owing to terrestrial exposure. Here we analyse an extract from a sample of asteroid (101955) Bennu collected by the OSIRIS-REx spacecraft and identify several bio-essential sugars, including ribose (RNA sugar) and glucose (metabolism substrate).
These sugars complete the inventory of ingredients crucial to life. Their distribution is consistent with that in the condensation products of formaldehyde solution. Given that Bennu contains formaldehyde and originates from an ancient parent asteroid that underwent long-term alteration by aqueous fluids, we postulate that the detected sugars formed in the parent asteroid from brines containing formaldehyde. This indicates that material with all three components necessary to life could have been dispersed to prebiotic Earth and other inner planets.
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