The Rosetta space probe, which is exploring Comet Churyumov-Gerasimenko (67/P according to the official classification), discovered molecular oxygen, which is older than our solar system, in the cloud of substances emitted by the object's nucleus into space (the so-called "coma"—a mixture of gases and dust). This discovery has stumped scientists and challenged several theories that had prevailed for decades.
"We never thought oxygen could survive for billions of years in its pure form, without combining with other substances, in the depths of a comet. Even more astonishing was the fact that the oxygen concentration was the same throughout all regions of the comet, indicating its incredible antiquity." – said Rosetta scientific team member Katherine Altwegg from the University of Bern.
Until now, cometary comas have primarily contained water, carbon monoxide, and carbon dioxide. Oxygen could only be found in cometary material as water, since it formed early in the formation of the solar system and would have subsequently reacted with hydrogen. However, the oxygen-to-water ratio remains stable, despite solar heating making the comet more active.
All this means, astronomers say, that molecules of "cometary" oxygen were present at the very beginning in a special substance that gave birth to our home solar system. Experts believe this primordial substance was preserved in its pristine form within cometary bodies. The oxygen found in the comet, according to scientists, does not fit within the accepted models of the formation of the solar system.
