What if there’s life on Mars, and we brought it there? The bacteria Deinococcus radiodurans can survive in space, hitchhiking a ride to the surface of Mars.
What if microbes were able to float freely in the vastness of space, like pollen in the wind, carried from one flower to the other, planting the seeds where new life would emerge? What if bacterial could do the same thing throughout the solar system and galaxy? Could life on Earth have begun like this? What is the survival rate of microscopic microorganisms such as bacteria in space?
An experiment on the International Space Station (ISS) has just shed new light on these questions, and it tells us that panspermia is far more likely than initially thought.
Whether alien life exists is one of the greatest enigmas in science. So far, Earth is the only planet that can sustain life as we know it, or at least that’s what we have learned this far. Nonetheless, life may exist in different places in the solar system, but we haven’t found it yet.
Good places to look for life are Mars, the atmosphere of Venus, and moons in the solar system such as Enceladus or Europa. This life, if it exists, may have developed there in the distant past, and is native to planets or moons.
However, a new study has now suggested that microscopic lifeforms, such as bacteria, may actually survive in space and could stay alive in a six-month journey from Earth to Mars.
A new study has suggested that certain types of bacterial could actually travel between Earth and Mars when forming aggregates. This raises concerns in regards to the prevention made on Earth when sending spacecraft, landers, and rovers to Mars.
A new research study, part of the Tanpopo astrobiological mission, showed that a genus of bacteria called Deinococcus are capable of surviving three years in the vacuum of space – resisting microgravity, intense radiation ultraviolet, and extreme temperatures, reveals Science Alert.
This means that not only can this type of bacteria survive in space, but it can also stay alive just long enough to send up on the surface of different cosmic bodies across the solar system.
Deinococcus measures between 1.5 and 3.5 nanometers in diameter and was found in the 1950s during an experiment to sterilize food using radiation.
The tenacious bacteria made meat to rot in an experiment even after being subjected to a high dose of gamma rays that killed all other microorganisms. In fact, it can survive a dose of 5,000 grays or 500,000 rad, of ionizing radiation with almost no loss of viability, whereas for a human a fatal dose equates to just 5 grays, the reason why it is unsurprising to find it can survive so long in the vacuum of space.
To see just how resistant in space the bacteria really is, colonies of the bacteria composed of different densities were exposed to the environment of space, outside the International Space Station for one, two, and three years in order to analyze their survival rate.
After three years, scientists found that all bacteria colonies larger than 0.5 millimeters had partially survived the harsh conditions of the vacuum of space (only the bacteria in the upper layer died), by generating a protective layer to the bacteria that were in the lower layers, which guarantees the survival of the colony.
Following the success of the experiment carried out by Japanese scientists, Deinococcus radiodurans has become a strong argument in favor of the panspermia theory, which suggests that life could have reached the Earth brought from another planet, for example, Mars. The existence of the bacteria also greatly increases the chances of life having developed in distant solar systems and other galaxies across the universe.
“The results of the study performed onboard the ISS suggests that bacteria such as Deinococcus could survive the journey from Earth to Mars and vice versa,” explained biologist Akihiko Yamagishi from Tokyo University.
In this sense, Mars, for example, may already be contaminated by us. It has previously been suggested that many bacterial spores from Earth have been transported to the surface of the red planet by the various spacecraft that have landed on Mars. Some of the bacteria may have been protected within Martian rovers and landers, which means that Mars may already have been interplanetarily contaminated despite our best effort to prevent this from happening.
If Deinococcus radiodurans can survive harsh environments such as the vacuum of space for years, and live long enough to reach Mars from Earth, what are the odds against it reaching the surface, somehow?
A recent study has also suggested that certain types of microorganisms exist inside the Earth that are able to survive without having developed the need to breathe. As revealed in a study published in Frontiers in Microbiology, researchers have explained that live independently using an ancient mode of energy production that does not involve breathing.
“They may be remnants of ancient forms of life that had been hiding and thriving in the Earth’s subsurface for billions of years.”
All of this makes me wonder if we already contaminated, not only Mars, the Moon, but other places in the solar system as well. Maybe life has sprung into existence in various places in the solar system in the last couple of decades, and were the messengers who transported it, seeding life across planets and moons.
If future missions do find life on Mars, will we be able to discern if it is native to the planet or brought there by us?