Wait, wait, wait. We’ve gone way too far with this. Allow us to represent a more scientifically precise thesis:
“Cosmic rays and their possible utilization”
And from here we shall begin!
Scientists have recently revealed a bizarre microbe found deep in a gold mine in South Africa that could provide a model for how life might survive in seemingly uninhabitable environments through the cosmos.
Known as Desulforudis audaxviator, the rod-shaped bacterium thrives 2.8 kilometers underground in a habitat devoid of the things that power the vast majority of life on Earth—light, oxygen, and carbon. Instead, this “gold mine bug” gets energy from radioactive uranium in the depths of the mine. Now, scientists predict that life elsewhere in the universe might also feed off of radiation, especially radiation raining down from space.
Most life on Earth’s surface takes in the energy it needs through one of two processes. Plants, some bacteria, and certain other organisms collect energy from sunlight through a process called photosynthesis. In it, they use the energy from light to convert water and carbon dioxide into more complex and energetic molecules called hydrocarbons, thus storing the energy so that it can be recovered later by breaking down the molecules through a process called oxidation. Alternatively, animals and other organisms simply feed off of plants, one another, etc., to steal the energy already stored in living things.
D. audaxviator takes a specific path:
It draws its energy from the radioactivity of uranium in the rock in the mine. The radiation from decaying uranium nuclei breaks apart sulfur and water molecules in the stone, producing molecular fragments such as sulfate and hydrogen peroxide that are excited with internal energy.
The microbe then takes in these molecules, siphons off their energy, and spits them back out. Most of the energy produced from this process powers the bacterium’s reproduction and internal processes, but a portion of it also goes to repairing damage from the radiation.
The radiation might not come from radioactive materials on the planet itself, but rather from galactic cosmic rays (GCRs)—high-energy particles that careen through the universe after being flung out of a supernova. They’re everywhere, even on Earth, but our planet’s magnetic field and atmosphere shields us from most GCRs.
The surfaces of other planets like Mars are much more susceptible to cosmic rays because of their thin atmospheres and, in the case of Mars, its lack of a magnetic field. Scientists argue GCRs could reach the Red Planet’s surface with enough energy left to power a tiny organism. This could also be the case on any world with a negligible atmosphere: Pluto, Earth’s moon, Jupiter’s moon Europa, Saturn’s moon Enceladus, and, theoretically, countless more outside our solar system.
Scientists do note, though, that because GCRs don’t deliver nearly as much energy as the sun, GCR-powered life would be very small, and simple, just like D. audaxviator.
Duncan Forgan, an astrobiologist at the University of St Andrews in the United Kingdom who was not involved with the work, agrees that Mars might be harboring D. audaxviator-like life because its stable temperatures and physical makeup are similar to that of the South African gold mine.
He does worry that on other planets that don’t receive light energy from a sun but still get bombarded with GCRs—such as free floating rogue planets not tied to any solar system—temperatures would dip too low and freeze life in its tracks.
He also cautions that too many cosmic rays could wipe life out altogether: “Life forms like this want a steady flux of energy from cosmic rays, but not so much that it’s damaging,” he says. “They might not be able to cope with a huge bout of radiation that pops in.”
In the future, scientists want to bring the gold mine bug into the lab and see how it responds to cosmic radiation levels equivalent to those on Mars, Europa, and others. That data would give them more clues to whether this kind of organism could survive beyond Earth.
“Desulforudis audaxviator is proof that life can thrive using almost any energy source available,” theysays. “I always think of Jeff Goldblum in Jurassic Park—life finds a way.”
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