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- Mar 1, 2002
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https://www.quantamagazine.org/radi...underground-and-inside-other-worlds-20210524/
Two papers appearing in February by different research groups now seem to have solved some of this mystery for cells beneath the continents and in deep marine sediments. They find evidence that, much as the sun’s nuclear fusion reactions provide energy to the surface world, a different kind of nuclear process — radioactive decay — can sustain life deep below the surface. Radiation from unstable atoms in rocks can split water molecules into hydrogen and chemically reactive peroxides and radicals; some cells can use the hydrogen as fuel directly, while the remaining products turn minerals and other surrounding compounds into additional energy sources.
Although these radiolytic reactions yield energy far more slowly than the sun and underground thermal processes, the researchers have shown that they are fast enough to be key drivers of microbial activity in a broad range of settings — and that they are responsible for a diverse pool of organic molecules and other chemicals important to life. According to Jack Mustard, a planetary geologist at Brown University who was not involved in the new work, the radiolysis explanation has “opened up whole new vistas” into what life could look like, how it might have emerged on an early Earth, and where else in the universe it might one day be found.
Astrobiologists are also realizing how crucial it might be to consider radiolysis when constraining the habitability of planets and moons throughout the solar system and the rest of the galaxy. Sunlight, high temperatures and other conditions might not be strictly needed to sustain extraterrestrial life. Radiolysis should be practically ubiquitous on any rocky planet that has water in its subsurface.
Two papers appearing in February by different research groups now seem to have solved some of this mystery for cells beneath the continents and in deep marine sediments. They find evidence that, much as the sun’s nuclear fusion reactions provide energy to the surface world, a different kind of nuclear process — radioactive decay — can sustain life deep below the surface. Radiation from unstable atoms in rocks can split water molecules into hydrogen and chemically reactive peroxides and radicals; some cells can use the hydrogen as fuel directly, while the remaining products turn minerals and other surrounding compounds into additional energy sources.
Although these radiolytic reactions yield energy far more slowly than the sun and underground thermal processes, the researchers have shown that they are fast enough to be key drivers of microbial activity in a broad range of settings — and that they are responsible for a diverse pool of organic molecules and other chemicals important to life. According to Jack Mustard, a planetary geologist at Brown University who was not involved in the new work, the radiolysis explanation has “opened up whole new vistas” into what life could look like, how it might have emerged on an early Earth, and where else in the universe it might one day be found.
Astrobiologists are also realizing how crucial it might be to consider radiolysis when constraining the habitability of planets and moons throughout the solar system and the rest of the galaxy. Sunlight, high temperatures and other conditions might not be strictly needed to sustain extraterrestrial life. Radiolysis should be practically ubiquitous on any rocky planet that has water in its subsurface.
