Tardigrades, the Earth’s most resilient species begs the question: what else is out there? The AFP reported that this microscopic, multicellular species, also known as the water bear, likely made it out alive following a crash landing on the lunar surface by Israel’s Beresheet probe in April, according to the US-based organization responsible for their trip..
Based on an analysis of the spacecraft’s trajectory and the composition of the device the micro-animals were stored in, “we believe the chances of survival for the tardigrades… are extremely high,” Nova Spivack, co-founder and chairman of the Arch Mission Foundation, told AFP, adding that the diminutive creatures, which are under a millimeter (0.04 inches) in size, had been dehydrated to place them in suspended animation, then “encased in an epoxy of artificial amber, and should be revivable in the future.”
The world’s most indestructible species, the tardigrade, an eight-legged micro-animal, will survive until the Sun dies, according to a 2017 Oxford University collaboration, The Resilience of Life to Astrophysical Events. “Tardigrades are as close to indestructible as it gets on Earth,” the researchers reported, “but it is possible that there are other resilient species examples elsewhere in the universe. In this context there is a real case for looking for life on Mars and in other areas of the solar system in general.”
“A lot of previous work has focused on ‘doomsday’ scenarios on Earth – astrophysical events like supernovae that could wipe out the human race,” said David Sloan, physicist at Oxford University in a July 14, 2017 post in The Galaxy about the tardigrade. “As we are now entering a stage of astronomy where we have seen exoplanets and are hoping to soon perform spectroscopy,” Sloan observed, “looking for signatures of life, we should try to see just how fragile this hardiest life is.
“To our surprise,’ Sloan added, “we found that although nearby supernovae or large asteroid impacts would be catastrophic for people, tardigrades could be unaffected. Therefore it seems that life, once it gets going, is hard to wipe out entirely. Huge numbers of species, or even entire genera may become extinct, but life as a whole will go on.”
“Without our technology protecting us, humans are a very sensitive species,” said Rafael Alves Batista, co-author of the Oxford study. “Subtle changes in our environment impact us dramatically. There are many more resilient species’ on earth. Life on this planet can continue long after humans are gone.”
“It is difficult to eliminate all forms of life from a habitable planet,” said Avi Loeb, co-author and chair of the Astronomy department at Harvard University. “The history of Mars indicates that it once had an atmosphere that could have supported life, albeit under extreme conditions. Organisms with similar tolerances to radiation and temperature as tardigrades could survive long-term below the surface in these conditions.
“The subsurface oceans that are believed to exist on Europa and Enceladus,” Loeb added, “would have conditions similar to the deep oceans of Earth where tardigrades are found, volcanic vents providing heat in an environment devoid of light. The discovery of extremophiles in such locations would be a significant step forward in bracketing the range of conditions for life to exist on planets around other stars.”
The study published in Scientific Reports, has shown that the tiny creatures, will survive the risk of extinction from all astrophysical catastrophes, and be around for at least 10 billion years – far longer than the human race. Although much attention has been given to the cataclysmic impact that an astrophysical event would have on human life, very little has been published around what it would take to kill the tardigrade, and wipe out life on this planet.
The research implies that life on Earth in general, will extend as long as the Sun keeps shining. It also reveals that once life emerges, it is surprisingly resilient and difficult to destroy, opening the possibility of life on other planets.
Tardigrades are the toughest, most resilient form of life on earth, able to survive for up to 30 years without food or water, and endure temperature extremes of up to 150 degrees Celsius, the deep sea and even the frozen vacuum of space. The water-dwelling micro animal can live for up to 60 years, and grow to a maximum size of 0.5mm, best seen under a microscope.
The researchers from the Universities of Oxford and Harvard, have found that these life forms will likely survive all astrophysical calamities, such as an asteroid, since they will never be strong enough to boil off the world’s oceans.
Three potential events were considered as part of their research, including; large asteroid impact, and exploding stars in the form of supernovae or gamma ray bursts.
There are only a dozen known asteroids and dwarf planets with enough mass to boil the oceans, these include Vesta and Pluto, however none of these objects will intersect the Earth’s orbit and pose a threat to tardigrades.
In order to boil the oceans an exploding star would need to be 0.14 light-years away. The closest star to the Sun is four light years away and the probability of a massive star exploding close enough to Earth to kill all forms of life on it, within the Sun’s lifetime, is negligible.
Gamma-ray bursts are brighter and rarer than supernovae. Much like supernovas, gamma-ray bursts are too far away from earth to be considered a viable threat. To be able to boil the world’s oceans the burst would need to be no more than 40 light-years away, and the likelihood of a burst occurring so close is again, minor.
Image credit top of page: Shutterstock