Molecular oxygen in comet’s atmosphere may alter solar system formation theory

BBC : Since rendezvousing with comet 67P/Churyumov–Gerasimenko in 2014, the Rosetta spacecraft has been sampling the comet’s atmosphere. In a new paper, Kathrin Altwegg of Bern University in Switzerland and her colleagues report that they were surprised by what the spacecraft found. Besides the expected water vapor, carbon monoxide, and carbon dioxide, Rosetta detected molecular oxygen, O₂, which appears to be the fourth most common gas in the comet’s atmosphere. Because of oxygen’s highly reactive nature, its discovery was unexpected. For it to be present in the atmosphere, the oxygen must have been frozen very quickly and become trapped in the body of the comet early in the formation of the solar system; it then gets released when the comet approaches the Sun and heats up. However, most theories about the formation of the solar system have proposed a violent process that should have kept the oxygen warm and gaseous. The possibility of a quieter formation process will require a reexamination of current formation models.