In the immortal words of Ian Malcom (Jeff Goldblum) “Life … um … finds a way”. Back in 2005, an article in Nature used the famous quote from Jurassic Park to describe the possibility of surviving life on Mars. It embodies the hope that the adaptability of life, which has so often proven itself on earth, could also apply to other planets. Now a new paper in astrobiology shows that there might well be a place where life on the red planet – just below the surface – can be preserved.
One thing that all life needs is a source of energy. Typically this source of energy on earth is the sun. However, there are cases when life uses other sources of energy, such as hydrothermal springs deep in the ocean. In fact, such environments are believed to have existed on Mars in the past. The team behind the new article, led by Jesse Tarnas, then a PhD student at Brown, found a slightly different non-solar energy source on Mars.
UT video about finding life on Mars.
Water is a key component in many chemical processes. Some of these processes release energy when they occur. Radiolysis occurs when rocks break down water trapped in their porous structure and then bombarded with radiation from the decay of radioactive isotopes in the rock formation. The broken water molecules release elemental oxygen and hydrogen.
Each of these molecular components play an important role in the biological process that sustains some types of microbes. The hydrogen is directly absorbed back into the water, while the oxygen can react with other materials such as pyrite (fool’s gold) to form a type of material known as sulfates. Bacteria have been found in isolated parts of the subsurface of the earth that eat up the hydrogen dissolved in the water and then use the oxygen formed with the sulfates to burn off the hydrogen and produce the energy necessary for life. It has been found that entire colonies of these sulfate-burning bacteria live a kilometer underground and have no source of energy other than the radiolysis process.
Graphic to show the radiolysis process.
Photo credit: NASA / JPL-Caltech / SETI Institute
Dr. Tarnas was interested in whether the materials needed to support this radiolysis process would be available in the Martian underground. Three of the main constituents they were looking for were radioactive elements like thorium or potassium, sulfides, which could be converted to sulfate by adding oxygen, and porous rocks, which could trap the water long enough for the radiolysis process to take effect.
To find these ingredients, the team looked at the most convenient sources – Martian meteorites. They found that all three major components of a radiolysis ecosystem were present in the meteorites they studied in sufficient quantities to support a bacterial colony similar to those found on Earth.
Persistence has a tool for looking underground on Mars known as the Radar Imager for the Mars Underground Experiment (RIMFAX – pictured above), but it would not be suitable for finding life that exists there could.
Photo credit: NASA / JPL – Caltech
This is not the first time the Brown team has addressed this issue. Instead, they analyzed gamma ray spectroscopy data from Odyssey as early as 2018 and came to a similar conclusion about the potential for life to arise in the subsurface of Mars. Brown’s team isn’t the only one looking for this off-earth process, either. Other teams have examined the potential for the process on ocean worlds.
Just because the environmental conditions are right does not mean that a bacterial colony actually exists. So far there has been no conclusive evidence of the existence of life on Mars. However, that does not prevent the scientists from looking. With this new research, there is now a stronger case for a mission specifically looking for underground life on the red planet. When a mission is started and life is eventually found there, that famous quote from Mr. Goldblum takes on a whole new meaning.
Learn more:
Brown – Mars has the right ingredients for today’s microbial life beneath its surface
Astrobiology – Earthlike habitable environments in the subsurface of Mars
Mining.com – Meteorites provide clues to the possible existence of microbial life on Mars today
UT – You’re going to need a bigger drill bit. The best place to live on Mars is deep, deep underground
Mission statement:
Jesse Tarnas, the paper’s lead author, collected samples in a mine shaft that, in its surroundings, could prove to be similar to the subsurface of Mars.
Photo credit: Jesse Tarnas
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