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The meek may well inherit the Earth |
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July 15, 2017 |
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By Eleanor Imster
EarthSky.org
The world’s most indestructible species, say
scientists, is the tardigrade, an eight-legged
micro-animal, also known as the water bear. The
tiny creature 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. That’s according
to a study published Friday in
the journal Scientific Reports.
The research implies that life on Earth in
general, will extend as long as the sun keeps
shining. It also suggests that once life
emerges, it is surprisingly resilient and
difficult to destroy, opening the possibility of
life on other planets.
Tardigrades are have a reputation as the
toughest, most resilient form of life on earth.
They can live for up to 60 years, are able to
survive for up to 30 years without food or
water, and endure temperature extremes of up to
150 degrees Celsius (300 degrees F), the deep
sea and even the frozen vacuum of space.
The tiny, water-dwelling animal – maximum size
is 0.5mm (.2 inches) – is best seen under a
microscope. The researchers – from the
Universities of Oxford and Harvard – say that
tardigrades will likely survive all
astrophysical calamities, including an asteroid,
since they will never be strong enough to boil
off the world’s oceans.
Rafael Alves Batista of the Department of
Physics at Oxford University, is a study
co-author. Batista said in a statement: "Without
our technology protecting us, humans are a very
sensitive species. 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."
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. 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.
According to an Oxford statement, 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.
* Asteroids: There are only a dozen known asteroids and
dwarf planets with enough mass to boil the
oceans (2×10^18 kg), these include (Vesta
2×10^20 kg) and Pluto (10^22 kg), however none
of these objects will intersect the Earth’s
orbit and pose a threat to tardigrades.
* Supernova: 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: 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.
It is difficult, the researchers say, to
eliminate all forms of life from a habitable
planet. In highlighting the resilience of life
in general, the research broadens the scope of
life beyond Earth, within and outside of this
solar system. |
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