14 July, 2017
Will our Earth be a no-man's land?
Most of Earth's life forms will only survive if the sun keeps shining.
The study, which was conducted by a team from Oxford University, examined a series of apocalyptic catastrophes and evaluated whether or not this creature could survive them.
Also known as "water bears", these eight-legged micro-animals live in the least habitable places on Earth, from Antarctica to the deep sea.
Despite a range of cataclysmic events that could put an end to our species - such as a large asteroid strike or a nearby exploding star - none would be serious enough to completely eradicate all life. They found it would be nigh impossible - once life takes root, it is surprisingly hard to eradicate. The tardigrade deemed to be an ultimate survivor on the Earth.
However, the hardy tardigrade could potentially survive even this. "As we are now entering a stage of astronomy where we have seen exoplanets and are hoping to soon perform spectroscopy [on those planets], looking for signatures of life, we should try to see just how fragile this hardiest life is".
Although supernovae or asteroid impacts would be catastrophic for humans, tardigrades could be unaffected. But the fact that tardigrades are so resistant to other potential apocalypses in the interim implies that "life is tough, once it gets going", Shostak says. "Species, or even entire genera may become extinct, but life as a whole will go on".
His Oxford colleague, Dr Rafael Alves Batista, contrasted the tardigrade's hardiness with human's relative fragility.
"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". Even subtle changes to our environment can have a drastic effect on our health. There are many more resilient species on Earth.
"There is a third scenario, where life continues around geothermal vents on a rogue planet until capture by a new host system, or the source of heat is extinguished... life could [endure] on a rogue planet long enough for it to be recaptured [into another solar system]."But researchers wanted to know what it would take to annihilate one of the world's most resilient creatures, so they turned to tardigrades. Instead, scientists considered star explosions (both supernovae and gamma ray bursts) and a major asteroid impact.
Astronomers have found a dozen asteroids and dwarf planets (including Vesta and Pluto) that are big enough to evaporate Earth's water upon impact, but none of these celestial bodies is on a collision course with our planet. However, none of them are on a trajectory to intersect with our orbit.
To boil away Earth's oceans, the researchers wrote, a gamma-ray burst would have to occur less than 40 light-years away, if it were aimed right toward Earth. Scientists have known for some time that tardigrades are almost impossible to kill - although they dwell in water, they can be without it for 30 years - but research published Friday in Scientific Reports takes that notion a step further: The species will live through every disaster until the sun itself explodes.
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