When the Sun turns into a red giant and swells to consume the Earth in a fiery death, we can be sure that there will be at least one living creature to experience the destruction. Able to survive the crushing pressures of both the deep-sea and the freezing vacuum of the space, the adorable tardigrades will outlive us all.
Due to the near impossibility to actually kill a tardigrade, which can survive for a fairly impressive 30 years without food or water, researchers looked into cataclysmic events that could potentially cause all life forms – including tardigrades – to be wiped out. They suggest boiling oceans may be what it takes. They identified three events that could cause this kind of event: large asteroid impact, supernovae, or a gamma-ray burst.
They found that there are only a handful of known asteroids and dwarf planets that have enough mass that if they were to hit Earth, they would boil the sea. The closest of these is the asteroid Vesta and dwarf planet Pluto, but the orbit of both of these mean that they are unlikely to intercept Earth before the Sun dies.
For a supernova or an exploding star to boil the water on our planet it would have to be ridiculously close. Within 0.14 light-years, to be precise. With our nearest star, aside from the Sun obviously, being some 4 light-years away this scenario can be ruled out too. Finally, the researchers then turned their attention to a gamma-ray burst, a brighter but rarer occurrence than supernovae. This would have to happen within 40 light-years, the odds of which are also pretty minor.
This means that water bears, an affectionate term for tardigrades, are most probably going to survive for an impressive 10 billion years, or until the Sun dies.
Despite giving the little moss piglets (another great nickname) some newfound respect the research actually gives an interesting look into what we could expect from life on other celestial bodies. Living creatures, it would seem, are far more resilient and much harder to wipe out entirely than we could have imagined, meaning that if life has evolved somewhere else in the universe, which it almost certainly has, it is most likely still knocking about.
“Tardigrades are as close to indestructible as it gets on Earth, but it is possible that there are other resilient species examples elsewhere in the universe,” says Dr Rafael Alves Batista, co-author of the paper published in Scientific Reports. “In this context, there is a real case for looking for life on Mars and in other areas of the solar system in general. If Tardigrades are Earth’s most resilient species, who knows what else is out there.”
So when we finally touch down on the Red Planet, perhaps we’ll find the water bears' Martian relatives.