Comet and Oxygen

At https://phys.org/print449835597.html … molecular oxygen found on Comet Churyumov-Gerasimenko back in 2016 is not produced on its surface according to an analysis of Rosetta data. Instead, it must have an origin in the interior of the comet. Instruments onboard Rosetta analysed the comet's coma and revealed it had water, carbon monoxide, carbon dioxide, and molecular oxygen. On Earth oxygen is essential for life – and it is thought to be produced by photosynthesis. It seems oxgen on Earth may also have an origin inside the planet – topped up by photosynthesis. Some hoary old ideas are being tested here – but downplayed. Further, researchers have found a new way to produce molecular oxygen in space – by energetic ions (electrically charged ions).