Discovery of oxygen on comet stuns scientists

PARIS—Stunned scientists on Wednesday announced the unexpected discovery of large quantities of oxygen on a comet which streaked past the sun in August with a European spacecraft in tow.

The find came as a “big surprise,” and would challenges mainstream theories on the formation of the solar system, said scientist Andre Bieler of the University of Michigan.

Measurements made by the Rosetta probe suggested that oxygen molecules in the 67P comet’s gassy halo must have existed “before or at” its formation, he told journalists.

This may have implications for mankind’s understanding of the chemistry involved in the formation of the solar system some 4.6 billion years ago.

“We believe this oxygen is primordial, which means it is older than our solar system,” said Bieler.

Scientists had previously ruled out the presence of oxygen (O2) on comets.

As O2 mixes easily with other elements, “we never thought that oxygen could ‘survive’ for billions of years” in a pristine state, said Kathrin Altwegg of the University of Bern, who coauthored a study in the journal Nature. “This evidence of oxygen as an ancient substance will likely discredit some theoretical models of the formation of our solar system.”

The comet is being tracked on its deep space journey around the sun by the European Space Agency’s Rosetta spacecraft.

The historic mission seeks to unlock the mystery of the origins of life on Earth.

Prevailing theories of the solar system’s birth posit a chaotic, collision-strewn mixing of matter flowing toward and away from the newly formed sun.

Only twice before on the icy moons of Jupiter and Saturn have oxygen molecules been found in the solar system beyond Earth’s atmosphere, and never before on a comet.

Oxygen is difficult to detect with earthbound telescopes.

The new data suggests that water on comets is probably the rule rather than the exception, the scientists said.

In looking at exoplanets, “the combination of O2 and methane has been taken as a sign that you might have life underneath,” Altwegg said. “On this comet we have both, but we don’t have life. So having oxygen may not be a very good bio-signature.”