There are few vermin as important for space exploration as tardigrades. In fact, tardigrades and sepiolids They usually have a reserved seat in NASA space missions for a reason. If they are so essential for science, it is because They are almost indestructibleso they serve as a thermometer to analyze the potential development and survival of living beings in extreme conditions. We have bad news: they survive the vacuum of space, radiation and extreme desiccation, but they can’t stand the soil of Mars.
The kryptonite of tardigrades. A research team put to the test to these very tough microscopic animals in the Martian regolith. The objective is twofold: they could serve to prepare arable soils on Mars and to better understand the risk of a potential escape of tardigrades from a possible human phase. Bad news: the Martian soil turned out to be toxic.
After two days of exposure to the artificial soil designed on Earth to simulate the characteristics of Mars MGS-1, not a single specimen of Hypsibius exemplaris was left alive. Ramazzottius S778 had better luck: some individuals survived. The research team observed an essential fact: by washing the soil simulant, the damage was greatly reduced. What does this mean? That the main suspect is a soluble chemical compound specific to Martian soil: perchlorates, oxidizing salts very abundant on Mars, such as detected the Phoenix probe almost two decades ago and confirmed the Curiosity rover.
Images of tardigrade samples with the simulant and exposure time in days. Corien Bakermans, Matteo Vecchi and Gillian Pearce
Why is it important. Because if we eventually want to send humans there and establish a base, we will first have to be able to grow food there and for that the Martian soil must be productive and capable of supporting terrestrial life. This study shows that as it is, that soil is toxic to even the most hardy animals on Earth. On the other hand, these results have direct consequences for the protection of the planets: if an organism escapes from a Martian habitat, we must know if it could survive in the Mars environment by contaminating it.
Context. Tardigrades have been the reference model for studying Extremophiles for decades. Thus, the TARDIS experiment in 2007 demonstrated that survive direct exposure to outer space and ultraviolet and ionizing radiation in a state of cryptobiosis (a state of extreme latency in critical environmental conditions). But it is one thing to resist in “off” mode and another in an active state, which is precisely what is of interest for eventual biological colonization. This experiment is precisely one of the first to test whether they can withstand these most vulnerable conditions and was carried out on simulated soils of Gale Crater, the area explored by the Curiosity rover.
In detail. To better understand the survival of tardigrades on Mars, the research team exposed populations of these animals only to the Martian simulants MGS-1 and OUCM-1, without including other conditions typical of the planet such as radiation, vacuum or extreme temperatures. For the comparison, they used terrestrial sand as a control and monitored how many individuals remained active throughout the study time (four days). Statistical analysis determined that survival depended on both soil type, species, and exposure time.
Yes, but. The results provide a good basis of information, but as the team explains, more testing is needed to fully understand the potential habitability and dangers of the Martian regolith. The next logical step will be to progressively incorporate the other environmental variables of Mars (radiation, pressure, temperature) in future experiments. This is, therefore, a study that is still very premature to know the ideal conditions for survival.
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