On October 28, 2015, the European Space Agency’s (ESA) Rosetta spacecraft detected large quantities of molecular oxygen in situ as it outgassed from Comet 67P/Churyumov-Gerasimenko’s coma (“tail”) for the very first time.
The Rosetta mission dates back to March 2004, where the spacecraft has travelled to and fro about the inner solar system, circling the Sun nearly four times in its quest towards Comet 67P.
Since over a year ago, Rosetta has discovered an abundance of various gases pouring from Comet 67P’s nucleus, the most abundant of which are water vapour and carbon monoxide. However, other compounds containing nitrogen, sulphur, carbon, and even noble gases have also been observed.
According to Andre Bieler, a scientist of the University of Michigan, the discovery of oxygen came as “a big surprise” to the Rosetta team. This discovery challenges mainstream theories about our solar system’s formation, so it undermines all that we know – or think we know – about the genesis of our known planetary objects.
Rosetta’s measurements of the comet suggest that the oxygen molecules in Comet 67P/Churyumov-Gerasimenko’s gassy tail must have existed “before or at” its formation. In Bieler’s words, they believe that “this oxygen is primordial,” meaning that “it is older than [the] solar system.”
Kathrin Altwegg of the University of Bern in Germany, another scientist tied with the Rosetta mission, admitted that her team “all went a little bit into denial.” After all, oxygen is not an element expected to be found in a comet’s coma since it is a highly reactive element.
For instance, in the presence of ultraviolet light, an oxygen molecule splits, forming a free oxygen. Then, the free oxygen can combine with another O2 molecule to form ozone, O3. Oxygen can also react with hydrogen from cold dust grains in outer space to form water – according to all current theoretical models of the solar system’s formation.
From September 2014 to March 2015, the group of Rosetta scientists analyzed over 3,000 samples collected from the spacecraft’s vicinity to isolate and identify the O2. Relative to water, oxygen had a presence of 1-10% and “an average value of 3.80 ± 0.85%”, which is higher than predicted values in accordance to theoretical models describing the chemistry in molecular clouds.
Interestingly enough, the amount of O2 detected by Rosetta showed a strong correlation with that of H2O at any given moment. With this finding, scientists believe that there is a connection between water and oxygen’s origin in the comet’s nucleus and the mechanism by which the comet releases them.
Ultimately, not only does Rosetta’s sighting of molecular oxygen from Comet 67P call into question our theoretical model for the solar system, but it could also change the present method with which scientists use to detect for signs of extraterrestrial life.
Presently, oxygen and methane are two “chemical signatures” that supposedly indicate signs of life; however, both gases have been detected on Comet 67P, and yet the comet supports no life itself. Thus, Altwegg evaluates that “[oxygen and methane are probably not] very good biosignature[s].”
Even though the relevance of Rosetta’s discovery is rather distant to our daily lives, I personally believe that it serves as a gentle reminder: What we think we know may not be reality as it is. Just because an idea or concept is accepted to be true by society at large doesn’t necessarily mean that it is correct.
We as humans produce our finest work when we embark on the journey to seek the truth. The more we question our surroundings, the more we’ll learn, and the closer we’ll arrive at genuinely understanding the world in which we live. The results of the Rosetta mission serve as a true testament to this philosophy.
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