If
the radiance of a thousand suns
Were
to burst forth at once into the sky
That
would be like the splendor of the Mighty One
I
am become Death
The
shatterer of worlds.
Bhagavad
Gita
Is
life indigenous to the planet Earth or did it come from somewhere
else? Could it be that are we truly aliens that originally visited in
the guise of organic chemicals and possibly even microbes that
evolved and eventually colonized this beautiful planet of ours? The
first mention of this possibility was Greek philosopher, Anaxagoras,
in the fifth century B. C. In the nineteenth century, several
preeminent scientists such as English physicist Lord Kelvin, Swedish
chemist Jons Jacob Berzelius and German physician/physicist Hermann
von Helmholtz suggested that there is a process whereby life was able
to plant itself from one world to another. The process is known
as panspermia; that is, that life arose on Earth and on other planets
via a system of transfer from outer space.
Ideas
abound as to how this transfer takes place. Late nineteenth century
Swedish chemist Svante Arrhenius in an article written in 1903
entitled The Distribution of Life in Space, suggested
that life arrived on Earth in the form of spores, pushed here by
radiation pressure.
Panspermia
has been dismissed by many scientists. One scientist, more famous as
a science fiction writer, Isaac Asimov, contended that the theory was
not worth consideration. Yet the theory does have a number of
heavyweight supporters. Francis Crick of Watson and Crick fame
(discoverers of the DNA molecular shape) believed that an alien race
is responsible for the transfer of life onto our planet. In fact, in
his book, Life Itself, he describes the type of
spacecraft needed to seed the planets. Sir Frederick Hoyle, the late
British astronomer who is ironically credited with the naming of the
“Big Bang Theory” origin of the universe while at the same time
advocating for the contradicting Continuous Creation Theory, believed
that life was transferred to our planet on comets. Later Hoyle and
Wickramsinghe proposed that it is possible that outbreaks such as
influenza and other epidemics actually have outer space origins.
A
number of experiments have shown that bacterial spores if exposed to
the true vacuum of space will be destroyed, but if there is any
protection such as being embedded in clay or artificial meteorites,
spores are capable of amazing feats of survival.
There
has also been some accidental demonstrations of the survivability of
bacteria in outer space. NASA’s Surveyor 3 landed
on the Moon on April 20, 1967 and remained in place on the Moon
until Apollo 12 which landed on November 19, 1969 in
the vicinity of the landing site of the earlier spacecraft. One of
the tasks of Apollo 12 astronauts was to collect
parts of the Surveyor spacecraft to return to Earth
for study of the long-term effects of the lunar environment on human
technology. The findings were nothing short of amazing. Embedded
within the camera was a colony of Streptococcus mitis, a
common Earth bacteria. It had survived the vacuum of space, radiation
and temperature extremes of the lunar surface, in a camera housing
for over three years. Though some scientists contended that the
contamination was more recent, it did not stop NASA from initiating
very strict protocols to prevent the contamination of
extraterrestrial worlds. In fact, the crashing of
the Galileo spacecraft into Jupiter was intentional
to prevent the possible contamination of Europa by earthly bacteria.
Similarly, NASA also crash-landed the Cassini space
probe into the parent planet, Saturn, to prevent the possible
contamination of one of the planet’s fascinating and possibly
life-baring moons.
There
is another form of more likely panspermia known as pseudo-panspermia
which involves the transfer of the building blocks of life to other
worlds. Once on those planetary surfaces, the process of chemical and
eventually life evolution takes over. It was Sir Frederick Hoyle and
Chandra Wickramsinghe who first showed that interstellar molecules
are formed by chemical reactions in the interstellar clouds of dust
and clouds. In fact, they contended that the near absolute zero
temperature of space within hydrogen clouds provided ideal conditions
for the creation of life, far better than the violence of an early
Earth.
Hoyle
and Wickramsinghe were dismissed when they first proposed their
ideas, but increasingly evidence mounted that they were indeed
correct, that the cosmos was a place in which complex organic
compounds could be found. In 2008, organic compounds were found in
the Murchison meteorite which had landed in 1969 in Australia. Within
the meteorite, over fifteen amino acids were found. In August 2012,
astronomers at Copenhagen University reported that they found a sugar
molecule in a distant star system. In September 2012, NASA reported
that polycyclic aromatic compounds are transformed after exposure to
interstellar conditions into complex organics. Then, in 2013,
researchers reported that they had found a pair of prebiotic
molecules in icy particles of outer space. As our instrumentation to
detect chemicals in the cold depths of space has increased so has the
frequency of the discovery of organic chemicals in space.
We
see that organics are found in the frozen reaches of outer space, but
how do they arrive on Earth? One way is through the destructive power
of a comet. The word “comet” comes from the Greek, meaning “hairy
star” which is a perfect description. To an earthbound person that
is exactly what they look like.
Comets
are fragile extraterrestrial bodies made up of ices such as carbon
dioxide, ammonia, methane, carbon monoxide and water as well as a
dusting of silicates and a sparse sampling of metals. Their orbits
are generally highly elliptical with orbital periods that range from
a few years to several million years. The most famous comet of all is
Halley’s Comet which was the first comet whose orbit was predicted
in 1705 by English astronomer Edmond Halley. A number of writers have
looked at Halley’s Comet as a setting for their tales. Perhaps the
one that is most scientifically accurate is by hard science fiction
authors, Gregory Benford and David Brin, who wrote in The
Heart of the Comet, about a mission to Halley’s Comet.
Arthur C. Clarke in his novel, 2061: Odyssey Three, also
describes a manned mission to the famous comet. Sir Frederick Hoyle,
one of the pioneers of the panspermia concept, wrote the simply
titled, Comet Halley, about life being discovered
there.
In
our lifetime humans have been witness to the destructive power of a
comet. Fortunately, it was the planet Jupiter that pulled the comet
from any possible course that could have resulted in an earthly
impact. It has been now speculated that for intelligent life to
evolve in a solar system, there needs to be a “cosmic vacuum
cleaner” such as a Jupiter to clean up cosmic debris such as comets
before they can destroy life that is evolving elsewhere in the
system.
In
July 1994, the Comet Shoemaker-Levy 9 hit Jupiter. It was almost as
if some supreme intelligence had wanted the human race to see the
event just to make us understand how lucky we are to have our island
in the sky, the planet Earth. Not only was the event seen by
earthbound telescopes, but by the Hubble Space Telescope, and
if that were not enough, by the Galileo spacecraft
which was situated to almost have a front-row seat to the event.
Another
delivery mechanism for spores and organics from space come in the
form of meteoroids. Meteoroids are rocky or metallic objects
travelling through space. As the meteoroid hits the Earth’s
atmosphere, it can appear as a meteor or “shooting star” as
friction with the Earth’s atmosphere heats the object up to
incandescence. When the object hits the ground it is known as a
meteorite. They can range anywhere from dust to pebbles to small
rocks and even large bodies such as the asteroid strike that killed
off the dinosaurs about 65 million years ago. It has been estimated
that up to fifteen thousand tonnes of debris falls to the Earth every
year from space.
The
source of meteoroids can be made up of ejecta from impacts on nearby
objects in our sky such as the Moon and Mars. In 1996, NASA
introduced a meteorite, essentially ejecta from Mars that has a
possible remnant of biological activity. Initially the news made
headlines around the world, but conservatism in science won the day
and public interest dwindled when scientists began to offer alternate
explanations for the structures. However, science does not stand
still and in 2009, scientists from the Johnson Space Center
reasserted the possibility that the meteorite
showed evidence of past life as the structure of the magnetite
particles found in the object are similar to those produced by Earth
bacteria. Scientists extrapolated that if that was the case, Martian
bacteria perhaps would produce similar particles. Unfortunately,
recent work has demonstrated that these same magnetite particles
could conceivably have been produced by shock waves as one might find
during the collision between a meteorite and a planetary surface.
Other
possible extraterrestrial sources of life on Earth can be an
asteroid. Asteroids can come from several regions of space. One of
the most likely is the asteroid belt that lies in between Mars and
Jupiter.
There
are literally millions of asteroids and there are estimated to be
between 1.1 and 1.9 million asteroids over one kilometer in diameter,
many which are shattered remains of objects that failed to coalesce
into larger planets. Most of them have a very stable orbit with
relatively low eccentricity. However, due to strikes by other objects
in the asteroid belt or perturbations of the effects of gravity, they
may stray from their paths to potentially become a threat to life on
Earth. The first asteroid that was discovered was Ceres in 1801
by Guiseppe Piazzi. It also happens to be the largest of the
asteroids with a diameter of 945 kilometers, After that, more and
more were being discovered. The name “asteroid,” meaning “star
planet,” was first coined by Sir William Herschel the discoverer of
Uranus.
Ceres
has provided the most inspiration to writers. The first was
written by Garrett Serviss who wrote Edison’s Conquest of
Mars in 1898 about Martians engaged in a war with giants
from Ceres. Jerry Pournelle’s Exiles to Glory describes
a Ceres that serves as the setting for an interplanetary mystery.
In Venus Belt by L. Neil Smith, Ceres is a world
that is strewn with a network of highways that link smaller
settlements to a large underground city. In The Stone
Dogs, by S. M. Stirling, Ceres is home to the Alliance for
Democracy.
In
spite of the evidence of organic molecules in space, on comets and
even meteorites, along with possible delivery mechanisms, there are
some critics of panspermia. However, there is indirect evidence that
it could be possible. For example, scientists are discovering
increasingly older rocks on Earth which contain the stuff of life. In
Greenland, the clock has been turned back 3.9 billion years.
Therefore, the gap between the early Earth formation and the
beginning of life is very narrow, making the possibility of seeding
from outer space more attractive.
More
evidence is suggested that the early Earth atmosphere may not have
been as conducive to life as was originally thought. The Urey/Miller
Experiment, conducted by Dr. Harold Urey and Dr. Stanley Miller in
1953, recreated what was believed to be an early Earth atmosphere and
exposed the mixture to an electric charge to mimic lightning. The
resultant soup contained amino acids, the building blocks of life but
something was wrong.
Amino
acids have a handedness much like you and me. In Earthly life-forming
amino acids, the handedness of the molecules is left, whereas in
Urey/Miller experiments the handedness of the resultant molecules was
both in equal amounts. Extraterrestrial amino acids, on the other
hand, which have been detected in interstellar clouds and in
meteorites show a “left” dominance as well.
Recent
analysis of comets by spacecraft show that they are riddled with
organics. Even recent ground based observations show that this
organic debris can be detected in the tails as well, meaning that a
catastrophic impact with a comet is not necessary to seed another
planet. When a comet passes through the inner solar system, part of
it begins to boil away as a gas with dust forming the tail. Some of
this dust is swept up by Earth’s gravity. NASA scientists have been
able to snag some of this cometary dust with the ER2 aircraft that
flies at twice the height of commercial jets. Analysis of the dust
indicates that over fifty percent of it is organic.
Since
the Earth is predominately covered by oceans, one would expect to
find a number of extraterrestrial particles in the ocean. One study
seems to verify this. In coastal seawater, there are over ten million
particles of extraterrestrial dust per quart.
Comets
can also release material to a planet or moon in the form of
meteorites. Every August, the Earth passes through the orbit of Comet
Swift-Tuttle, displaying one of amateur astronomy’s annual
highlights, the Perseid meteor shower.
Certainly
the possibility of meteorites being a source of alien organic
chemistry or even microbes is not lost to science fiction. In an
interesting tale by Paul Preuss, Small Bodies, a
fundamentalist preacher and a scientist discover fossils on an
asteroid. Interestingly enough, though Preuss’ tale is fiction,
there may be an actual scientific analogue. A meteorite that may hold
some promise of life from outside the Earth, but also a lot of
disagreement in the scientific community, is the Polonnaruwa
meteroite that fell in December 29, 2012 in Sri Lanka. Chandra
Wickramasinghe published that his team had found fossilized diatoms
inside the meteorite. One problem is that peers did not recognize the
rock as a meteorite and therefore are not recording nor analyzing it.
It
is, therefore, very possible that the Earth was seeded by organics
and perhaps even bacteria from the comets, asteroids and even
meteorites of the past. However, what would happen with the energy of
impact? Calculations show that the heat generated by impact or
explosion actually still allows the organics to arrive intact on
Earth.
The
evidence is mounting. Perhaps life on our planet is not native at
all. It may mean that we are truly alien and that our early
space-faring predecessors were blessed with finding this rich and
varied planet for the taking. The more evidence that there is for
panspermia also bodes well for life elsewhere not only in our Solar
System but in the rest of the universe as well. Life
may indeed have been created in the empty reaches of space and
colonized the planets through transmission of materials by comets.
Hoyle has been vindicated and the theory that was blasted by
Asimov as being unworthy of consideration is gaining a following.
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