Panspermia The Origin of Life on Earth
[Applause]
the origin of life on earth is one of
our greatest mysteries
could life on earth have originated
elsewhere from our universe
could the comets that brought water to
earth have also brought the bacteria
that evolved into the rich variety of
life we see around us
today panspermia is a radical theory
that was first proposed by the ancient
greeks
it suggests that life can spread from
planet to planet in our universe and
could mean that our ancestry traces back
to an as yet undiscovered world
the theory suggests that tiny microbes
or bacteria can become embedded in rocky
debris which is then ejected into space
following collisions between planets
asteroids and comets
these asteroids and comets can then
travel to other habitable worlds crash
land on the surface and kickstart the
evolution of life once more
panspermia is certainly not a proven
process and not widely accepted by the
scientific community
but with thousands of distant planets
now detected in our galaxy the hunt is
on to detect a signal of life from one
of these distant worlds
i’d like to take you on a short journey
today exploring how life may be much
more widespread than previously thought
and how life may regenerate to populate
the universe
for many years the ingredients for life
have been discovered inside rocks
orbiting the solar system
and inside some rocks that have crash
landed on earth
these ingredients are formed of the same
elements as life on earth elements like
carbon nitrogen oxygen hydrogen
in 1969
meteorite landed in australia called the
merchants and meteorite
several studies since then have found
the evidence for amino acids the
building blocks for proteins and dna
buried within fragments of this
meteorite
another study was conducted last year
that found more evidence of complex
organic matter within fragments of this
meteorite
in 2014 the european space agency’s
filet lander probe surveyed a distant
comet in our solar system called comet
67p
as it was orbiting the comet it detected
the signs of organic matter in the
atmosphere around the comet
just before it touched down on the
surface of the comet
it sent its signals back to earth
reporting that the majority of the comet
was formed of water ice with a thin
layer of dust around the outside
in 1990 a meteorite fell in algeria
just last year a team in america
reported the first ever detection of a
long complex protein inside a fragment
of this meteorite
this is the first ever complex protein
detected inside a meteorite ever
the findings of these chemicals inside
rocks in our solar system suggests that
that they could be responsible for for
transferring matter across our solar
system
but could these rocks also transmit life
around our solar system or even further
afield
how far would life have to travel
between planets and what is the chance
of it surviving such a brutal trip
well space is a pretty inhospitable
place you won’t find many five-star
reviews on tripadvisor for outer space
the launch is pretty harsh you’ve got to
survive the intense vacuum and radiation
of your journey and then the landing at
the other end is almost as harsh
what kind of life forms could survive
such a journey
could life-forms have began life
elsewhere and traveled towards earth
for panspermia to have any scientific
merit
we need proof that life can survive
these types of extreme journeys
and we know of several life forms that
can indeed survive such a journey
one of the cutest animals that can
survive in outer space
is a tiny micro animal called a
tardigrade also known as a water bear
these are tiny microscopic eight-legged
animals discovered about 150 years ago
these animals can survive extreme
conditions here on earth the hottest
temperatures the coldest temperatures
the highest pressures at the bottom of
the ocean and they can even survive in
the vacuum of space
despite being known as water bears they
can actually survive for decades without
any water at all in a state of suspended
animation
many years ago hundreds of tardigrades
or water bears were flown into orbit
around earth for 12 days mounted to the
outside of a rocket a pretty
uncomfortable trip
this would have killed any other animal
but not the humble tardigrade most of
them survived completely unharmed and
unfazed
just this year more tardigrades water
bears were launched to the international
space station to investigate how their
genomes may help them survive the harsh
conditions of outer space
whilst the water bears are perhaps the
cutest animals that could survive in
outer space it’s much more likely that
tiny microscopic bacteria are the
passengers responsible for spreading
life in our universe
the most interesting type of bacteria
that could survive this trip is called
danococcus radiodurans
this is an extremophile bacteria you can
put it in any harsh conditions you like
and most of them will survive in
addition to surviving in extreme
temperatures and pressures they have a
special skill
they can withstand intense bursts of
radiation like the kind they experience
in outer space
and they can automatically repair their
own dna a feature not yet found in any
other life forms
many of these bacteria were launched
onto the international space station
this year as part of a japanese space
agency program called tan popo tan popo
is the japanese word for dandelion
and the word dandelion was chosen for
the experiment because it was thought
that the seeds of the dandelion drifting
through space resembled the seeds of
life spreading throughout our galaxy
but what happened to these these
bacteria on the space station
they were exposed to the harshness of
space for one two and three years
the vast majority of them survived by
using a thin layer of dead bacteria
almost like an umbrella to protect the
colony belief from the harmful radiation
so we know that these bacteria can
survive for at least three years
but scientists think that in fact they
can survive long enough to travel
between any two locations in the solar
system
certainly from earth to mars to venus to
the moons of saturn or the moons of
jupiter
but instead of bacteria traveling from
earth to another location
what about bacteria that’s traveled from
another location to earth
well we may all have martian ancestry
and it may not be just the men who are
from mars
hundreds of rocks on earth have been
traced back to the red planet via their
chemical composition
just this year nasa’s perseverance rover
touched down in the jezero crater on
mars
the rover is looking for signs of life
in addition to surveying the martian
climate and the martian geology
we think that mars was once a very
habitable world
full of liquid water stable warm
temperature and a thick atmosphere
the jezero crater itself where the rover
is currently was once a large lake with
its own river system
the rover is looking for signs either
that life once existed on mars billions
of years ago or is still there buried
beneath the surface
if life did exist on mars perhaps it all
died out after the evaporation of the
martian atmosphere
but perhaps it survived by going
underground later being transported to
earth via panspermia
such a trip from mars to earth would
take a couple of years not too long on
the cosmic scale
again the bacteria would have to
withstand the intense pressures of being
launched into space following a
collision the intense radiation and the
vacuum of space and then the harsh
landing at the other end
and we know that bacteria can in theory
survive this trip
but what about a longer journey
our milky way galaxy could be exchanging
life across vast distances
this depends on a number of factors
including the distance between the stars
and the planets how fast the comets or
the asteroids are traveling
how much material gets ejected into
space after a collision and of course
how long the organisms can survive for
the most likely place to find this kind
of interstellar panspermia is in
clusters of stars really dense groups of
stars and we find several of these
within our own milky way galaxy
if we’re looking for panspermia anywhere
these are the locations that we might
find it
we have evidence for these longer
distance transits within the last few
years
in 2017 a small rocky object named
umuamua which i believe is hawaiian for
traveler was found entering our solar
system
it passed our sun
past the planet and return to the cold
dark space
between the stars
in 2019 another small rocky object was
detected entering our solar system a
small comet a few kilometers wide
nicknamed borisov
these two objects could not have been
created within our own solar system
they’re moving far too fast around two
hundred thousand kilometers per hour
they must have come from a different
star system
comet borisov came probably from a
relatively close red dwarf star system
named kruger 60.
it began life as an icy remnant orbiting
around its home star
came slightly too close to another
planet or a comet
was ejected out of its orbit and
traveled and accelerated towards our own
solar system
this journey could have taken millions
of years
but we think some bacteria could survive
this trip by going into a state of
hibernation and coming back into life at
the opposite end
we need more evidence if we’re going to
believe any such crazy theory
there are currently two probes
investigating whether the theory of
panspermia could be true
the nasa probe osiris-rex and the
japanese craft hayabusa ii are currently
orbiting the solar system looking for
more evidence of organic matter in
distant asteroids and comets and they
may return more evidence that our solar
system really is littered with the
ingredients for life itself
panspermia is quite a novel theory and
again it’s not widely accepted in the
scientific community
but if it is responsible for spreading
life around our cosmos there may be a
huge number of life forms out there
waiting to be discovered
depending on who you are and what you
believe some people think that life is
rare and can only form here on earth
some people believe that life can form
on any planet given the right conditions
entirely independently
but some people believe
that life can all form from the same
primordial seed scattered across the
galaxy via panspermia
i wonder how that might change the
opinion here on earth if we discovered
distant life on another planet
well with thousands of habitable planets
now detected many of which full of
liquid water the hunters on to be the
first to detect a signal of life from
one of these distant worlds
i wonder how that might change things on
earth
it’s amazing to think
that the story of life on earth many
billions of years in the making
could have begun with our distant
ancestors on a far away planet a long
long way away thank you
[Applause]