Scientific experiments are full of surprises. Just recently, researchers have shown that lab-grown comet ice contains ribose and other sugars, which are believed to be building blocks for RNA and DNA and molecules integral to all known forms of life.
The experiment opened up the possibility of ribose and similarly structured sugars being assembled under cosmic ice conditions during the formation of the solar system. The compound, according to scientists at the University of Nice Sophia Antipolis in France, had not been previously detected in cometary ice or meteorites.
For study author and astrochemist Cornelia Meinert, successfully identifying ribose and other sugar molecules in the artificial comet was “new and entirely unexpected.”
“[This] is relevant for many theories on the origin of life,” she says in an email interview with Discovery News.
DNA and RNA are the genetic materials of all living creatures on Earth, including viruses. Science has long pondered on the origin of these compounds, with some believing that the planet was seeded by comets or asteroids containing basic building blocks needed for the formation of the molecules.
A number of amino acids and nucleic acid components, in fact, have already been detected in meteorites as well as lab-made comets. Ribose, RNA’s other key component is only recently created under astrophysical settings when French scientist teams simulated ice making up comets.
The team placed a mix of water, methanol, and ammonia at low temperatures and pressures, simulating the creation of comets’ raw material, or dust grains with ice coating. They then irradiated the material with ultraviolet light, and upon analyzing it with highly sensitive techniques, they detected sugars and ribose, which were suggested to form from formaldehyde.
The experiment is rooted from previous work to craft an organics detector for the Philae lander, dispatched by the Rosetta spacecraft in 2014 on the surface of Comet 67P/Churyumov-Gerasimenko. While the lander of the European Space Agency (ESA) did not find ribose on the comet, it captured three organic materials that also appeared in the experiment.
For astronomer Donald Brownlee, who was not involved in the study, ribose is a prerequisite to life that can survive entry to the atmosphere. Meteorites are hot on the surface, but not in the interior, and cosmic dust hailing from comets probably carry the sugar through the atmosphere, he explains.
The question, he proposes, is whether our planet could manufacture ribose, as irradiating frozen volatile materials can easily take place in space, but not on Earth.
The research team is yet to figure out how or why exactly these sugar molecules formed in artificial ices, but plan to further probe their nature and structure in hopes of shedding more light on DNA evolution.
The findings were published April 8 in the journal Science.
