High-speed ions make Comet 67P a surprising source of molecular oxygen
There’s a lot of oxygen in space, but not in a form you can breath. Thanks to the respiration of plants on Earth, our bodies have evolved to use O2, known as molecular oxygen, to pull off our own metabolic processes. Outside of our delightful atmosphere, the most likely place to find oxygen in the cosmos is bonded to other elements like hydrogen and carbon. O2 isn’t distributed equally around the universe, and scientists were starting to look at it as a marker of an Earth-like, habitual planet. However, newly released data from the Comet 67P/Churyumov-Gerasimenko is making us reconsider this most precious molecule yet again.
When the Rosetta spacecraft first reported molecular oxygen near Comet 67P, the assumption was that it was being released from deep within the comet’s core. As the comet got closer to the Sun, it warmed up, melting ice and loosening up, releasing gases that were normally frozen solid, including O2. This O2 would have then been some of our solar system’s original supply of oxygen, created 4.6 billion years ago alongside our Sun. However, unrelated research serendipitously suggested that O2 might not created as infrequently as previously assumed.
Synthesizing O2 with solar wind
Konstantinos Giapis looked at the data from the Rosetta spacecraft not from a geologists perspective, but from his experience as a chemical engineer developing microprocessors. His work involved studying the interactions between high-powered ions and semiconductor surfaces, usually for the purpose of improving memory components in computers. Giapis happened to be curious about this data from space, and recognized that the oxygen on Comet 67P was emerging in similar conditions to those he usually created in his lab.
The emerging hypothesis is that the molecular oxygen seen wafting off of Comet 67P isn’t from the birth of the solar system, and is instead being created as the comet orbits the Sun. Water molecules from ice inside the comet are indeed being released, but ions from the Sun, collectively known as solar wind, are actually breaking those water molecules apart. More oxygen is also being freed from rust and sand on the outside of the comet, and these loose atoms can then bond into new O2.
If this is confirmed, it’s good to know but certainly complicates our model of the universe. There had been hope that O2 could be an indicator of life on distant exoplanets, but knowing that it these molecules can be made with debris and the ions means that it’s not always going to be a sign of respiration. O2 is still rather unusual, but we now know there are more ways to get a hold of some if you don’t have any plants around.
Source: Comet 67P Found to Be Producing Its Own Oxygen in Deep Space by Nancy Atkinson, Seeker