Comet 67P, which the European Space Agency’s Rosetta spacecraft has been orbiting for more than a year, is blowing molecular oxygen (O2) out into space, an astonishing new study in Nature reports.
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The revelation came as quite a shock. “It is the most surprising discovery we have made so far, because oxygen was not among the molecules expected in a cometary coma”.
Prof Kathrin Altwgg, project leader for one of Rosetta’s measuring devices, the mass spectrometer, said she and her colleagues had been startled by the discovery. The third most abundant element in the universe is actually very hard to find outside of Earth, especially in its breathable O2 form.
According to the paper, most comet comas are comprised of up to 95 per cent molecular water (H20) and molecular carbon dioxide (CO2), with the remaining five per cent comprised of other molecules.
This new oxygen study appears to suggest that the models may, in a few way, be incorrect, but a lot more work will need to be done before anyone can definitively say that this interpretation is correct. After making sure their results were correct, they then looked to find out how the O2 could be there. As it flew farther away, it detected less. Exo-fauna hunters view the presence of oxygen and methane as positive hints for life on distant planets since both molecules are often produced by primitive life forms. This occurs when energetic particles coming off the sun break up the bonds of water ice. Nevertheless, oxygen molecules were present on the comet. These particles only penetrate a few metres into the surface, however. In each of its revolutions around the Sun, though, the comet loses between one and ten metres from its circumference. Using instruments aboard the Rosetta probe, which orbits the rubber duck-shaped comet, scientists discovered its existence in a halo around the comet, according to a paper published today in the journal Nature.
Pristine, icy grains containing oxygen would not have made it through such violence intact, the scientists said, leading them to speculate that the process was, in fact, “gentler”. The tools on Rosetta already found earlier this year that the comet had its own kind of water. “The detection of molecular oxygen is new and very surprising. It starts to give you a peek into the environment in which the solar system formed”.
The findings lead to two puzzles for computer modelers to tackle. Comet 67P is not the only object in space that has been detected with molecular oxygen, several moons of Jupiter and Saturn have also been detected with molecular oxygen in past discoveries.
“The comet shows us there are situations we hadn’t considered, and this will happen over and over again”, said Professor Seager. However, high levels of O2 in an exoplanet’s atmosphere could still reflect extraterrestrial life.
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The only other possibility is that the O2 had been trapped inside the comet and was being released as its host shed its surface material during its close solar encounter.
