The search for extraterrestrial life has ended up looking a lot more like Biology 101 than Prometheus.
Instead of ancient alien megastructures, we’re mostly looking for xenobacteria that can survive the harsh radiation, thin atmospheres, and extreme temperature changes of other planets. Mars has been a strong candidate for a while, but scientists had almost resigned themselves to the belief that whatever evidence of life we find on the Red Planet, it’s going to be past life.
However, a new study from Lomonosov Moscow State University may have given us a new hope.
In the study, scientists focused less on temperature and pressure conditions as the most dangerous factors for life (though they still simulated Martian conditions in their experiments) and instead focused on ionizing radiation.
Ionizing radiation is the extremely nasty stuff, the kind that can bathe a planet’s surface when there’s little atmosphere. Absorbed radiation is usually measured in Grays (shortened to ‘Gy’), and the human tolerance is usually around 4-10 Gy.
Some microorganisms, however, have displayed much higher tolerance—somewhere between 1,800 and 5000 Gy.
Well, in this study they subjected different types of microorganisms to around 100 kGy, or 10,000 Gy, all while keeping them in Martian conditions…in permafrost.
According to the study:
“We have studied the joint impact of a number of physical factors (gamma radiation, low pressure, low temperature) on the microbial communities within ancient Arctic permafrost. We also studied a unique nature-made object-the ancient permafrost that has not melted for about 2 million years. In a nutshell, we have conducted a simulation experiment that covered the conditions of cryo-conservation in Martian regolith. It is also important that in this paper, we studied the effect of high doses (100 kGy) of gamma radiation on prokaryotes’ vitality, while in previous studies no living prokaryotes were ever found after doses higher than 80 kGy.”
That’s a lot to throw at tiny critters that don’t even have a cell nucleus.
The upshot is that no prokaryotic beings had ever survived in the conditions tested, and prokaryotes are hypothesized to be the progenitors of the first living organisms.
This means that there may be life hiding in the Martian soil, or even other celestial bodies floating around the solar system.
“The results of the study indicate the possibility of prolonged cryo-conservation of viable microorganisms in the Martian regolith. The intensity of ionizing radiation on the surface of Mars is 0.05-0.076 Gy/year and decreases with depth. Taking into account the intensity of radiation in the Mars regolith, the data obtained makes it possible to assume that hypothetical Mars ecosystems could be conserved in an anabiotic state in the surface layer of regolith (protected from UV rays) for at least 1.3 million years, at a depth of two meters for no less than 3.3 million years, and at a depth of five meters for at least 20 million years. The data obtained can also be applied to assess the possibility of detecting viable microorganisms on other objects of the solar system and within small bodies in outer space.”
It just goes to show: never count out extremophiles. Life, uh, finds a way.