DNA Sequencing Microchip Could Detect Earth-Like Life on Mars
Conditions on Mars are harsh. Its atmosphere is made up mostly of carbon dioxide and is 100 times thinner than Earth’s. Temperatures on the surface can plummet to minus-126 degrees Celsius. But the environment below the Martian surface may be similar to our own planet and may hold all the major elements required for life, some scientists say.
Does life still exist on Mars, even today? And if it does, could it somehow be related to life on Earth?
These are questions that many planetary scientists, astrophysicists and others interested in the emerging field of astrobiology are asking.
In the quest for answers, a team of scientists from MIT, Harvard University, Caltech, Brown University and Massachusetts General Hospital in the United States have proposed a new method for determining whether life on Earth could have originated on Mars, or vice versa. These researchers have developed a DNA sequencing microchip that can detect and decode RNA and DNA sequences in microbes harvested from alien environments, such as those that exist on Mars. RNA and DNA are clear and unmistakable indicators of life, and if microbes examined on both planets demonstrate certain commonalities is could reveal surprising secrets about how life truly evolved in our solar system.
“If there’s life on Mars and it is based on RNA and DNA, you would get not one but many sequences and you’d be able to understand the relatedness of any Earth life,” explained project leader Christopher Carr, a professor in the department of Earth,Atmospheric and Planetary Sciences at MIT.
Between four and 3.5 million years ago, Earth and Mars went through a period of heavy bombardment by meteorites and asteroids. Major impacts could have blown materials off the planet surfaces and out into space, creating new meteorites that may have traveled the gravitational path between Earth and Mars, going in either direction on this interplanetary highway.
“If life was around on one planet or the other, it could have hitched a ride and ended up on the other planet,” said Carr. Many scientists believe this type of cross-contamination could have taken place approximately 3.5 billion years ago, creating a situation where life might have evolved on each planet in parallel.
It isn’t clear if DNA sequencing technology could determine the direction of the contamination. But it would be able to distinguish between actual Martian life and microorganisms that originated on Earth, but were accidentally carried to the planet by a Mars mission.
The new DNA sequencing microchip would be the core element in a larger device that could be transported to Mars on a future NASA rover mission. Carr and his fellow researchers have named this device the Search for Extra-terrestrial Genomes (SETG) instrument, and with financial and logistical assistance from NASA their exploratory tool remains under development.
Crucial radiation testing has already been completed, and it has verified that the SETG DNA sequencing microchip can be protected against radiation damage during space travel or while on the Martian surface
The SETG initiative has been highly publicized. But it is not the only research and development project focusing on astrobiological DNA sequencing.
In partnership with NASA’s Ames Research Center in California, in 2018 the Canadian Space Agency sponsored a study involving a DNA sequencing device called MiniOn, which was designed and manufactured by Oxford Nanopore Technologies in the United Kingdom.
In the search for testing grounds with similar characteristics to the Martian landscape, a team of researchers headed by McGill University professor Lyle Whyte deployed MiniON on the frozen permafrost of Axel Heiberg Island, just 900 kilometres from the North Pole. This island features a series of cold, salty perennial springs that are known to host microbial life. Even in this inhospitable environment, the MiniOn was able to detect these microorganisms and accurately record their DNA and RNA sequences.
Meanwhile, research carried out at the University of Arkansas-Fayetteville in the United States has confirmed the viability of microbial life on Mars.
The atmosphere on Mars is known to contain quantities of the gas methane, which can be created either by volcanoes or by the actions of microbes called methanogens. These organisms don’t require oxygen, and if they lived just below the surface of Mars they would be shielded from the destructive effects of ultraviolet radiation penetrating Mars’s super-thin atmosphere. The Arkansas-Fayetteville experiments revealed they could survive the red planet’s lack of atmospheric pressure as well, meaning that they could actually be responsible for creating the methane that currently floats above the Martian surface.
Future Destinations in the Search for Life
While much of the attention has been focused on Mars, this is not the only body in the solar system identified as a possible source of life. Three of Jupiter’s moons (Europa, Callisto and Ganymede) and three of Saturn’s moons (Enceladus, Titan and Mimas) may have subsurface oceans trapped beneath their icy exteriors, any of which could conceivably host microscopic (or even larger) forms of life. Even on Pluto, evidence suggests that liquid oceans may be found several kilometres below its rigidly frozen surface.
The Hubble Space telescope spotted eruptions of water from beneath the ice on Europa, while the Cassini Space Probe identified geysers spouting high in the air above the surface of Enceladus. These two moons are considered top candidates for future exploration, which could be carried out by rovers similar to those now being routinely sent to Mars.
Pluto may be beyond our reach, but the moons of Jupiter and Saturn may be future destinations for unmanned missions searching for signs of life. Should life be found in any of these locations, it is unlikely to be traced to cross-contamination, as the separation between Earth, Mars and these far-off bodies is simply to great for meteorites to bridge the gap.
Immersed in a Living Universe?
In life is found in one or more of these locations, it may have evolved separately and independently from life on Earth. It might be that conditions conducive to life have an inherent tendency to produce life, wherever those conditions might be found.
One intriguing possibility is revealed through the doctrine of panspermia. The developers of this hypothesis suggest that the universe is teeming with microorganisms and other building blocks of life, which can be transported across vast distances of space on comets, asteroids or meteorites. If a comet from the depths of interstellar space crashed into the Earth billions of years ago, it could have seeded the planet with alien life, and if similar objects hit other planets or moons it could have caused the same effect.
If life is indeed discovered to exist on more than one planet or moon in our otherwise unremarkable solar system, it could mean that life is abundant throughout the galaxy and beyond. It would signal the possibility that wherever life is possible it is likely to develop, meaning life is not a fluke or rare occurrence but a predictable emergent outcome in a universe designed to produce it.
How much of that life might be intelligent is of course a matter for speculation.
Top image: The search for life on other planets. Credit: Sergey Nivens / Adobe Stock
By Nathan Falde