Comet 67P/Churyumov-Gerasimenko has stunned scientists with the unexpected detection of oxygen molecules out-gassing from the comet. It suggests that the molecules were incorporated into the comet during its formation.
In a news conference held by Nature, Kathrin Altwegg, one of the study’s authors who is in charge of Rosetta‘s ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis), said: “It is the most surprising discovery we have made so far, because oxygen was not among the molecules expected in a cometary coma.”
“It’s also unanticipated because there aren’t very many examples of the detection of interstellar O2. And thus, even though it must have been incorporated into the comet during its formation, this is not so easily explained by current Solar System formation models,” Altwegg added.
The European Space Agency‘s (ESA) spacecraft Rosetta has been studying Comet 67P for over a year now. It has been able to detect a number of different gases coming from its nucleus, with water vapor, carbon monoxide, and carbon dioxide being the most prolific. Other gases that were detected include; nitrogen-, sulfur- and carbon-bearing species, and even “noble gases” were also recorded, according to ESA.
Watch ODN take on the discovery:
Andre Bieler of the University of Michigan and co-author told journalists that the measurements made by Rosetta have suggested oxygen molecules in 67P gassy halo must have existed “before or at” its formation.
If this is the case, then this could have implications on our understanding of the chemistry that was involved during 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.
The presence of oxygen (O2) on comets like 67P had been previously ruled out by scientists, because O2 mixes easily with other elements. “We never thought that oxygen could ‘survive’ for billions of years” in such a pristine state, said Altwegg, of the University of Bern.
She added: “This evidence of oxygen as an ancient substance will likely discredit some theoretical models of the formation of our Solar System.”
Even though oxygen is the third most abundant element in the Universe, the simplest molecular version O2 has been hard to find, even in star-forming clouds. This is because it’s highly reactive and will readily break apart to bind with other atoms and molecules, explained ESA.
For example, oxygen atoms can combine with hydrogen atoms on cold dust grains to form water, or a free oxygen split from O2 by ultraviolet radiation can recombine with an O2 molecule to form ozone (O3). Despite its detection on the icy moons of Jupiter and Saturn, O2 had been missing in the inventory of volatile species associated with comets until now, the ESA added.
Rosetta mission finds oxygen on comet 67P — a report by euronews (in English):
Altwegg said in a statement: “We weren’t really expecting to detect O2 at the comet — and in such high abundance — because it is so chemically reactive, so it was quite a surprise.”
The Rosetta spacecraft was designed to try and unlock the secrets of the origins of life on Earth, and has been tracking the comet during its space journey around the sun.
According to PHYS ORG: 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. Scientists believe that comets had “seeded” early Earth with some of the ingredients needed for life on Earth.
But the study authors say that the pristine, icy grains that contain the oxygen would not have survived through such violence intact, which has led to speculation that the process was much “gentler.” With Altwegg saying that the oxygen molecules must have “survived from the dark molecular clouds from which they were probably formed into comets as we have them today.”
Matt Taylor, ESA’s Rosetta project scientist, said in a statement: “This is an intriguing result for studies both within and beyond the comet community, with possible implications for our models of Solar System evolution.”