In the popular mobile device science fiction game, Lifeline, a survivor of a crashed ship has a frightening experience on the surface of a distant world. The planet’s surface, under the protagonist’s space-suited feet, begins to quake, and alien ooze pours out through the cracks in an attempt to consume the survivor. That can’t happen right? According to a recent article published in the academic Astrobiology journal, life on other planets most likely exists in the cracks.
A team of scientists studied the faults, primarily caused by earthquakes, in the Outer Hebrides (a group of islands off the coast of Scotland). They noticed that elements and chemicals, such as hydrogen, were abundant in the rocks; abundant enough for bacterial life to survive. So how can life exist in this precarious state, especially without light or energy?
According to the article, the Earth’s crust contains radioactive elements. Almost all rocks contain some key elements, but in magmatic and metamorphic rocks, high traces of Uranium and Thorium can be found. These elements slowly decay and create radiation that splits water into hydrogen and oxygen. Organisms can then use this hydrogen to reduce gases and minerals present in the rocks to gain free electrons, which can be used to feed chemical reactions to sustain the organism's life.
In 2008, the bacterium Desulforudis audaxviator was found 9,800 feet below the Earth’s surface in the Mponeng mine in South Africa. The environment was very hot with a very high pH-value of 9.3. Scientists believe that this microorganism survived by enjoying a diet of nitrogen and sulfate pulled from the surrounding rocks and by cannibalising dead bacteria.
By studying the faults, the scientists found that this type of feeding process can occur basically anywhere, even in incredibly hostile conditions, so long as the elements were present in the rocks. If a planet is tectonically active, fluids and water can freely flow over these rocks freeing up hydrogen for the little bacterial buggers. Even if the planet does not experience earthquakes, meteor and asteroid strikes can provide enough local movement on the crust for faults to open up. As Jeff Goldblum put it in Jurassic Park...