Space rocks that fell to Earth contain
ribose, an essential molecule for life’s genetic machinery, and other
related sugars. The finding, reported online November 18 in Proceedings of
the National Academy of Sciences, lends support to the idea that many of
life’s ingredients were delivered to Earth by interplanetary debris.
Many organic molecules have been found in space. Comet
Lovejoy, for example, carts
around sugar and alcohol, the base ingredients for a decent interplanetary
cocktail (SN: 10/23/15). But until now, no one had confirmed an
extraterrestrial source for ribose. This molecule forms part of the
sugar-phosphate backbone of RNA, molecular workhorses within cells responsible
for reading and carrying out instructions encoded in DNA.
Yoshihiro Furukawa, a geochemist at Tohoku University in Sendai,
Japan, and colleagues found the ribose, along with several chemically similar
sugars, in samples from two meteorites, one collected from Morocco, the other
from Australia. By measuring the amounts of carbon-13 in the sugars — a variant
of carbon with an extra neutron, which appears more often in organic molecules
from space than in their terrestrial counterparts — the team found that the compounds
likely originated in space and weren’t picked up on Earth.