Oxygen detected near Chury
“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,” says Kathrin Altwegg of the University of Bern, and principal investigator of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument, ROSINA.
Hard to track down
Rosetta has been studying comet Chury for over a year now. Altwegg’s team has collected and analysed over 3000 samples in which a wide range of different gasses have been detected. Noble gasses as well as carbon monoxide were found, but now oxygen can be added which has large implications.
Oxygen is the third most abundant element in the Universe, but the simplest molecular version of the gas, O2, has proven surprisingly hard to track down, even in star-forming clouds, because it is highly reactive and readily breaks apart to bind with other atoms and molecules.
Intriguing result
The amount of molecular oxygen detected by Altwegg and her team showed a strong relationship to the amount of water measured at any given time, suggesting that their origin on the nucleus and release mechanism are linked. By contrast, the amount of O2 seen was poorly correlated with carbon monoxide and molecular nitrogen, even though they have a similar volatility to O2. In addition, no ozone was detected.
The presence of oxygen in the vicinity of comet Chury suggests the molecules were there when the comet was formed, 4.6 billion years ago. “This is an intriguing result for studies both within and beyond the comet community, with possible implications for our models of Solar System evolution,” says Matt Taylor, ESA’s Rosetta project scientist.
