- Is there life on Mars? If so, it is likely microbial and deep below the surface, where temperatures are warmer and it is protected from the harsh surface conditions.
- The best place to search is beneath a vast plain called Acidalia Planitia, in the northern hemisphere, according to a new study from Spain.
- Any microbes there might be methanogens, organisms that expel methane as a byproduct. They might help explain the puzzling mystery of methane in Mars’ atmosphere.
Are there microbes on Mars?
Does life exist anywhere on Mars today? Mars’ surface is extremely cold, with a whisper-thin atmosphere and harsh radiation coming from the sun. But some scientists think living microbes might survive deep below the surface of Mars. And now, researchers in Spain say they’ve identified the best place to search: Acidalia Planitia, a vast plain in Mars’ northern hemisphere. The researchers said that microbes on Mars would most likely be methanogens, which are also found on Earth, and which leave behind methane as a byproduct. It’s a scenario that might help explain the mysterious presence of small amounts of methane in Mars’ atmosphere.
Astrophysicist Paul M. Sutter wrote about the news in Universe Today on December 21, 2024. The researchers submitted their peer-reviewed paper to the journal Astrobiology on November 22, 2024. A preprint version is also available on arXiv.
Mars-like conditions on Earth
Andrea Butturini at the University of Barcelona in Spain led the new study. The research team looked for locations on Earth that could be analogs for the Martian environment. These are also places where methanogens exist. Methanogens are anaerobic (requiring an absence of free oxygen, that is, oxygen that is not a part of a compound) archaea that produce methane as a byproduct of their metabolism. The researchers found three kinds of locations that were analogous to Mars. As Sutter wrote in Universe Today:
The researchers found three potential Mars-like conditions on Earth where methanogens make a home. The first is deep in the crust, sometimes to a depth of several kilometers, where tiny cracks in rocks allow for liquid water to seep in. The second is lakes buried under the Antarctic polar ice cap, which maintain their liquid state thanks to the immense pressures of the ice above them. And the last is super-saline, oxygen-deprived basins in the deep ocean.
Earthly analogs where methanogens thrive
Those kinds of conditions also exist on Mars. So, could methanogenic-types microbes live there?
On Earth, the researchers mapped out the analog locations. They measured temperature ranges, salinity (salt) levels and pH values (acidity). In addition, they measured the abundance of molecular hydrogen at those locations. With all the data, the research team determined specifically where methanogens were most abundant.
Then, the data were compared to data from Mars, to find which locations on Mars were the most similar to those on Earth where methanogens thrived. One region in particular stood out: Acidalia Planitia. This is a vast plain in the northern hemisphere of Mars. It is a geologically rich region, with evidence for past hot springs, steam vents, glaciers and even possible mud volcanoes and oceans.
Here, conditions are the most similar to the Earthly analogs. Not on the surface, but rather below it. Several miles deep, in fact.
Acidalia Planitia, by the way, was the landing region for the human mission to Mars in both the book and movie “The Martian.”
Landing site in Acidalia Planitia featured in The Martian (top right). pic.twitter.com/zXkJ2lhLJu
— Andrew Rader (@marsrader) October 2, 2015
HiPOD: Pitted Mounds in Acidalia Planitia
This image in the Acidalia Planitia region of Mars shows numerous round hills that have a large circular depression on their tops. These pitted mounds may be ancient mud volcanoes.https://t.co/148A3dTnRJ
NASA/JPL-Caltech/UArizona#Mars pic.twitter.com/r9zZMusGw5— HiRISE: Beautiful Mars (NASA) (@HiRISE) July 19, 2023
Acidalia Planitia, the best place for life on Mars?
The paper stated:
The intense debate about the presence of methane in the Martian atmosphere has stimulated the study of methanogens adapted to terrestrial habitats that mimic Martian environments. We examinate the environmental conditions, energy sources and ecology of terrestrial methanogens thriving in deep crystalline fractures, sub-sea hypersaline lakes and subglacial water bodies considered as analogs of a hypothetical habitable Martian subsurface.
We combine this information with recent data on the distribution of buried water or ice and radiogenic elements on Mars and with models of the subsurface thermal regime of this planet to identify a 4.3-8.8 km-deep [2.6-5.4 miles] regolith habitat at the mid-latitude location of Acidalia Planitia, that might fit the requirements for hosting putative Martian methanogens analogous to the methanogenic families Methanosarcinaceae and Methanomicrobiaceae.
The paper concluded:
As a result, both our analysis (which builds upon recent advances in understanding Mars’ subsurface) and previous research more focused on its surface converge in identifying the southern of Acidalia Planitia as a promising target area for future missions in the search for extant life in Mars’ subsurface.
Still a challenging environment
Even though conditions beneath the surface in Acidalia Planitia are far better than on the surface, it would still be a challenging environment for microbial life. As the paper noted:
Methanogens are significant, but not ubiquitous, in the microbial ecosystems thriving in the subsurface ecosystems believed to be terrestrial analogs of the Martian subsurface. Thus, although methanogens feed on simple molecules and their metabolism can be described by straightforward redox equations – making them ideal models for astrobiologists – studies of terrestrial deep temperate-hot crystalline fractures are revealing that these habitats are challenging for methanogens. Consequently, the cold Martian subsurface is likely an even harsher habitat for putative terrestrial-like methanogens.
Beyond the need for water, appropriate environmental conditions, and adequate energetic and carbon resources, the proliferation of methanogens also depends on complex ecological constraints. Indeed, methanogens establish ecological and energetic interactions with organisms with diverse metabolisms, suggesting that the conjecture that they might form mono-specific communities does not fit with what is regularly observed in terrestrial subsurface ecosystems. So, if terrestrial-like methanogens were to thrive in Mars’ subsurface, they would most likely be members of a complex and diverse ecosystem.
More study needed
The paper said:
The subsurface of the southern of Acidalia Planitia is a putative target region for hosting cold-adapted Methanosarcinaceae-like and/or Methanomicrobiaceae-like methanogens (if they can associate with bacteria-like organisms). In this region, the radiogenic heat-producing elements are at the highest abundance and subsurface water is likely. Thus, water radiolysis could supply the energetic resources required for these hypothetical methanogens.
Our knowledge of Mars’ subsurface is advancing thanks to orbiters, landers and rovers, but critical gaps exist. To make substantial progress in identifying habitable niches in the subsurface of Mars, it will be essential to elucidate the availability of inorganic carbon in the subsurface, and to determine more accurately the depth at which water is located and the porosity/fracturing of the regolith, as these factors directly affect the thermal gradients and the efficiency of water radiolysis.
Needless to say, actually finding any evidence for microbes that far below the Martian surface will be difficult. Even now, rovers can only drill a matter of inches – or a few feet as with the upcoming ExoMars rover – into the ground or rocks. But perhaps another future mission will be able to analyze the puzzling methane emissions even closer, and determine whether they have a biological or non-biological source. That could reveal the existence of the hypothetical methanogens without having to dig at all.
Bottom line: A new study suggests that microbes on Mars might exist deep below the surface, and in one region in particular. They might even explain Martian mysterious methane.
Source: Potential habitability of present-day Mars subsurface for terrestrial-like methanogens
Read more: Want to find life on Mars? Look deep underground
Read more: The strange case of methane on Mars: Possible new answers
The post Are methane-belching microbes on Mars hiding underground? first appeared on EarthSky.
from EarthSky https://ift.tt/Pnal5pk
- Is there life on Mars? If so, it is likely microbial and deep below the surface, where temperatures are warmer and it is protected from the harsh surface conditions.
- The best place to search is beneath a vast plain called Acidalia Planitia, in the northern hemisphere, according to a new study from Spain.
- Any microbes there might be methanogens, organisms that expel methane as a byproduct. They might help explain the puzzling mystery of methane in Mars’ atmosphere.
Are there microbes on Mars?
Does life exist anywhere on Mars today? Mars’ surface is extremely cold, with a whisper-thin atmosphere and harsh radiation coming from the sun. But some scientists think living microbes might survive deep below the surface of Mars. And now, researchers in Spain say they’ve identified the best place to search: Acidalia Planitia, a vast plain in Mars’ northern hemisphere. The researchers said that microbes on Mars would most likely be methanogens, which are also found on Earth, and which leave behind methane as a byproduct. It’s a scenario that might help explain the mysterious presence of small amounts of methane in Mars’ atmosphere.
Astrophysicist Paul M. Sutter wrote about the news in Universe Today on December 21, 2024. The researchers submitted their peer-reviewed paper to the journal Astrobiology on November 22, 2024. A preprint version is also available on arXiv.
Mars-like conditions on Earth
Andrea Butturini at the University of Barcelona in Spain led the new study. The research team looked for locations on Earth that could be analogs for the Martian environment. These are also places where methanogens exist. Methanogens are anaerobic (requiring an absence of free oxygen, that is, oxygen that is not a part of a compound) archaea that produce methane as a byproduct of their metabolism. The researchers found three kinds of locations that were analogous to Mars. As Sutter wrote in Universe Today:
The researchers found three potential Mars-like conditions on Earth where methanogens make a home. The first is deep in the crust, sometimes to a depth of several kilometers, where tiny cracks in rocks allow for liquid water to seep in. The second is lakes buried under the Antarctic polar ice cap, which maintain their liquid state thanks to the immense pressures of the ice above them. And the last is super-saline, oxygen-deprived basins in the deep ocean.
Earthly analogs where methanogens thrive
Those kinds of conditions also exist on Mars. So, could methanogenic-types microbes live there?
On Earth, the researchers mapped out the analog locations. They measured temperature ranges, salinity (salt) levels and pH values (acidity). In addition, they measured the abundance of molecular hydrogen at those locations. With all the data, the research team determined specifically where methanogens were most abundant.
Then, the data were compared to data from Mars, to find which locations on Mars were the most similar to those on Earth where methanogens thrived. One region in particular stood out: Acidalia Planitia. This is a vast plain in the northern hemisphere of Mars. It is a geologically rich region, with evidence for past hot springs, steam vents, glaciers and even possible mud volcanoes and oceans.
Here, conditions are the most similar to the Earthly analogs. Not on the surface, but rather below it. Several miles deep, in fact.
Acidalia Planitia, by the way, was the landing region for the human mission to Mars in both the book and movie “The Martian.”
Landing site in Acidalia Planitia featured in The Martian (top right). pic.twitter.com/zXkJ2lhLJu
— Andrew Rader (@marsrader) October 2, 2015
HiPOD: Pitted Mounds in Acidalia Planitia
This image in the Acidalia Planitia region of Mars shows numerous round hills that have a large circular depression on their tops. These pitted mounds may be ancient mud volcanoes.https://t.co/148A3dTnRJ
NASA/JPL-Caltech/UArizona#Mars pic.twitter.com/r9zZMusGw5— HiRISE: Beautiful Mars (NASA) (@HiRISE) July 19, 2023
Acidalia Planitia, the best place for life on Mars?
The paper stated:
The intense debate about the presence of methane in the Martian atmosphere has stimulated the study of methanogens adapted to terrestrial habitats that mimic Martian environments. We examinate the environmental conditions, energy sources and ecology of terrestrial methanogens thriving in deep crystalline fractures, sub-sea hypersaline lakes and subglacial water bodies considered as analogs of a hypothetical habitable Martian subsurface.
We combine this information with recent data on the distribution of buried water or ice and radiogenic elements on Mars and with models of the subsurface thermal regime of this planet to identify a 4.3-8.8 km-deep [2.6-5.4 miles] regolith habitat at the mid-latitude location of Acidalia Planitia, that might fit the requirements for hosting putative Martian methanogens analogous to the methanogenic families Methanosarcinaceae and Methanomicrobiaceae.
The paper concluded:
As a result, both our analysis (which builds upon recent advances in understanding Mars’ subsurface) and previous research more focused on its surface converge in identifying the southern of Acidalia Planitia as a promising target area for future missions in the search for extant life in Mars’ subsurface.
Still a challenging environment
Even though conditions beneath the surface in Acidalia Planitia are far better than on the surface, it would still be a challenging environment for microbial life. As the paper noted:
Methanogens are significant, but not ubiquitous, in the microbial ecosystems thriving in the subsurface ecosystems believed to be terrestrial analogs of the Martian subsurface. Thus, although methanogens feed on simple molecules and their metabolism can be described by straightforward redox equations – making them ideal models for astrobiologists – studies of terrestrial deep temperate-hot crystalline fractures are revealing that these habitats are challenging for methanogens. Consequently, the cold Martian subsurface is likely an even harsher habitat for putative terrestrial-like methanogens.
Beyond the need for water, appropriate environmental conditions, and adequate energetic and carbon resources, the proliferation of methanogens also depends on complex ecological constraints. Indeed, methanogens establish ecological and energetic interactions with organisms with diverse metabolisms, suggesting that the conjecture that they might form mono-specific communities does not fit with what is regularly observed in terrestrial subsurface ecosystems. So, if terrestrial-like methanogens were to thrive in Mars’ subsurface, they would most likely be members of a complex and diverse ecosystem.
More study needed
The paper said:
The subsurface of the southern of Acidalia Planitia is a putative target region for hosting cold-adapted Methanosarcinaceae-like and/or Methanomicrobiaceae-like methanogens (if they can associate with bacteria-like organisms). In this region, the radiogenic heat-producing elements are at the highest abundance and subsurface water is likely. Thus, water radiolysis could supply the energetic resources required for these hypothetical methanogens.
Our knowledge of Mars’ subsurface is advancing thanks to orbiters, landers and rovers, but critical gaps exist. To make substantial progress in identifying habitable niches in the subsurface of Mars, it will be essential to elucidate the availability of inorganic carbon in the subsurface, and to determine more accurately the depth at which water is located and the porosity/fracturing of the regolith, as these factors directly affect the thermal gradients and the efficiency of water radiolysis.
Needless to say, actually finding any evidence for microbes that far below the Martian surface will be difficult. Even now, rovers can only drill a matter of inches – or a few feet as with the upcoming ExoMars rover – into the ground or rocks. But perhaps another future mission will be able to analyze the puzzling methane emissions even closer, and determine whether they have a biological or non-biological source. That could reveal the existence of the hypothetical methanogens without having to dig at all.
Bottom line: A new study suggests that microbes on Mars might exist deep below the surface, and in one region in particular. They might even explain Martian mysterious methane.
Source: Potential habitability of present-day Mars subsurface for terrestrial-like methanogens
Read more: Want to find life on Mars? Look deep underground
Read more: The strange case of methane on Mars: Possible new answers
The post Are methane-belching microbes on Mars hiding underground? first appeared on EarthSky.
from EarthSky https://ift.tt/Pnal5pk
