Since the 17th century, scientists and astronomers have searched for clues of life on Mars through every method available to them. While the search for Martian life began by peering through telescopes, we now have the ability to send autonomous robotic rovers to the Martian surface to dig through the soil by hand. Creepy robotic hand, that is.
While concrete evidence of life on Mars has yet to be found, there have been some recent promising developments. Evidence of flowing water on Mars, including a massive underground frozen lake, has been found which gives some hope to the theory that where there is water, there is likely life. However, scientists are still uncertain if the geological and atmospheric conditions of the planet are hospitable for any forms of life. Just last year, however, a team of Dutch scientists found that Martian soil - the most abundant resource on the barren planet - is capable of sustaining plant life.
Now, more promisingly, a new research project at the NASA-funded University of Arkansas Center for Space and Planetary Sciences have found that Mars could indeed have the necessary conditions to sustain certain microbial life forms. The study resolved one of the most enduring questions surrounding life on Mars: whether or not any life could withstand the low Martian atmospheric pressure. To test this question, researchers placed four separate species of methanogens - microbes which survive on ambient hydrogen and carbon dioxide - into a hypobaric chamber which simulated conditions on Mars. According to the published data, the microbes survived for days, meaning they could hypothetically survive the Martian climate:
The study reported here tested the survivability of four methanogen species under low pressure conditions approaching average martian surface pressure (6 mbar – 143 mbar) in an aqueous environment. Each of the four species survived exposure of varying length (3 days – 21 days) at pressures down to 6 mbar.
The Martian atmosphere pressure ranges anywhere from one-hundredth to one-thousandth of Earth’s. Water does not easily stay liquid at pressures so low, which could be one reason why liquid water has yet to be found on the Red Planet. Despite the lack of water, this research shows that life could exist in places we haven't examined yet, such as deep below the Martian surface.
In a NASA press release, lead researcher Rebecca Mickol stated that while this study gives researchers hope in the search for life on Mars, more testing is of course needed before any firm conclusions can be drawn:
These experiments show that for some species, low pressure may not really have any effect on the survival of the organism. The next step is to also include temperature.
Temperatures on Mars fall far below temperatures found on Earth, meaning any potential life on Mars would have to survive an extremely inhospitable environment. However, given that microbial life has been found in some of the most inhospitable depths of our own planet, it’s not an impossibility that life might indeed be somewhere on Mars.