Scientists were shocked to discover pristine oxygen molecules detected by the European Rosetta mission control head: 'A perfect moment'Rosetta# aircraft on a comet.

"It is the most surprising discovery we have made so far on 67P, because oxygen was not among the molecules expected in a cometary coma," said Kathrin Altwegg of the University of Bern, who co-authored a study published Wednesday in the science journal Nature.

The information was gathered as Comet 67P/Churyumo-Gersimenko streaked past the Sun in August towing the European Space Agency's Rosetta spacecraft.

"We believe this oxygen is primordial, which means it is older than our solar system," said scientist Andre Bieler of the University of Michigan, who contributed to the study.

Before the discovery, scientists ruled out the possibility of oxygen (O2) due to the molecule's ability to easily mix with other elements. However, the latest discovery poses challenges to theories on the formation of earth's solar system.

Sara Seager, a planetary science professor at the Massachusetts Institute of Technology who was not involved in the study, said the findings were a "wake-up call."

"The findings will add fuel to the fire for an already ignited debate about O2's false-positive scenarios," Seager said, according to AP news agency.

ls/jil (AFP, AP)