The Mystery of Oxygen in the Atmosphere of a Comet

The Mystery of Oxygen in the Atmosphere of a Comet

Comets might have Molecular Oxygen stored in them for as long as 4.5 billion years. Rosetta team stick to their idea that traces found inside Coma came from within 67P.

Molecular Oxygen is an essential commodity for life on Earth and that’s the reason why it is considered a sign while searching for life in other parts of the universe. This combination of two Oxygen atoms is produced by plants during Photosynthesis and they release them into the atmosphere. Many moons of the Jupiter are considered potential candidates for extraterrestrial life as scientists found its traces around them. Despite all these detections, it was never found around a comet until Rosetta spacecraft of the European Space Agency escorted Churyumov-Gerasimenko (67P). The spacecraft remained in space from August 2014 to September 2016 before crashing onto the surface of the Sun. It encountered the comet quite close to the Sun’s surface and found molecular Oxygen in its surroundings.

When a comet comes too close to the Sun, the ice on its surface sublimes to form a gaseous atmosphere called Coma. Rosetta performed an analysis of this coma and found Carbon Dioxide, Carbon Monoxide, and water vapors. The surprising thing was that molecular Oxygen was also traced in that mixture. The initial reports of the researching team of Rosetta suggested that the nucleus of the comet was the source of this Oxygen. It was a massive statement because it meant that the gas was already there when the comet was formed at the beginning of the Solar System. This information shocked the world and consequently, different theories were proposed about this finding.

One of these propositions came from a group of scientists who had figured out a way to create molecular Oxygen in space. They told the world that the process of creating Oxygen can be initiated through electrically charged ions. They elaborated that a lot of energetic ions are present on the surface of 67P and they could be the reason for this Oxygen instead of the core of the comet. This created enough doubt in the minds of the researchers of the Rosetta team and they decided to give it a second look.

They analyzed the 67P’s data about Oxygen in accordance with this new theory and the results were published in ‘Nature Communications’ on 3rd July 2018. According to the scientists, the proposed mechanism for producing Oxygen on the surface of the comet doesn’t satisfy the quantity of the gas that was found by the Rosetta spacecraft. Kevin Heritier, the Lead Author of the study who is a Representative of the Physics Department of the Imperial College London, talked about their findings in the following words:

The first detection of molecular oxygen in 67P’s coma was both very surprising and exciting. We tested the new theory of surface molecular oxygen production using observations of energetic ions, particles which trigger the surface processes which could lead to the production of molecular oxygen. We found that the number of energetic ions present could not produce enough molecular oxygen to account for the amount of molecular oxygen observed in the coma.”

According to these reports, the original conclusion of the team is still the most accurate explanation of all the other proposed theories. Some of the recent researches that were done to strengthen the opinion that the molecular Oxygen existed in the early solar system also supported this theory. According to those models, Oxygen froze onto small dust particles which gathered more and more material to form comets. Despite that, none of the theories can be neglected currently as we have limited information at our disposal.

The researchers of Rosetta team do acknowledge that some of the molecular Oxygen could be formed at the surface of the comet but at the same time, they are confident that it is not the only source. Dr. Marina Galand, who is the Co-investigator of the Rosetta Plasma Consortium, referred to that as she said,

Surface generation of molecular oxygen may still happen on 67P, but the majority of the molecular oxygen in the coma is not produced through such a process.

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