Plutonians
When Pluto was discovered in
1930, most astronomers believed there was life on Mars and perhaps on Venus.
But Pluto was so cold that no-one seriously believed it was inhabited. One of
the few astronomers who seriously entertained the idea was George Van Biesbroeck
of Yerkes Observatory, who speculated “[If] there is a form of life on the new
planet we can be sure it is totally different from that on the earth.”
Fiction writers, however, had
been given a whole new world to play in, and a steady stream of Plutonians
appeared in fiction. The first appearance of Pluto as an inhabited planet was
in H P Lovecraft's The Whisperer in
Darkness, written in September 1930 though not published until the next
year. However, the creatures who lived on Pluto were not born there - Pluto was
far too parochial for Lovecraft's monsters, and was just a stopping-off point :
"Their main immediate abode is a still undiscovered and almost lightless
planet at the very edge of our Solar System—beyond Neptune, and the ninth in distance from
the sun. It is, as we have inferred, the object mystically hinted at as
'Yuggoth' in certain ancient and forbidden writings; and it will soon be the
scene of a strange focussing of thought upon our world in an effort to facilitate
mental rapport. I would not be surprised if astronomers became sufficiently
sensitive to these thought-currents to discover Yuggoth when the Outer Ones
wish them to do so." The creatures call themselves the Mi-Go, and are
"a sort of huge, light-red crab with many pairs of legs and with two great
bat-like wings in the middle of the back."
True Plutonians were introduced
in 1931 by Stanton A Coblentz in his novelette Into Plutonian Depths. It is the first story to be set on Pluto,
but there's nothing much to distinguish the setting from Earth; though dim,
chilly and bleak, the air is breathable, the gravity is the same as Earth's and thick furs are all
that is required to keep the two visitors from Earth comfortable. They reach
Pluto by coating their vessel with a substance that cuts off gravity - the very
same means that H G Wells used to get his visitors to their otherworldly
destination in his 1901 novel The First
Men in the Moon. In both books
the travellers comprise a brilliant scientist-inventor accompanied by a
man-in-the-street companion. In both, too, the inhabitants of the world they
visit are frail and spindly underground dwellers (which makes good sense in a
low-gravity lunar setting, but not on Coblentz's Pluto, with its Earth-normal
gravity).
The Plutonians are equipped with natural lanterns on their
heads which have been evolved to illuminate the dark tunnels they inhabit (a
problem Wells solved by means of a luminous liquid flowing
round a system of underground channels). The lamps also glow with different colours
according to the emotions of the Plutonians. There are three genders on Pluto:
male, female and neuter. The neuters are surgically produced and held in great
esteem because only they have the necessary freedom from sexual impulses to
become great scientists or poets.
Stanley
Weinbaum's The Red Peri is the first story set on Pluto to take into
account known conditions there - such as they were in 1935, when the story was
written. All that was certain about Pluto were the size and shape of its orbit
and its dimness - which meant that it could not possibly be a large, brightly
reflective world like its neighbour Neptune. If it was as reflective as the
other planets, it must be tiny (which turned out to be correct). If it were as
large as Neptune - or even as the Earth - it must be a very dark world. This is
what Weinbaum assumed: a coal-black planet, somewhat bigger
than our own, with a gravitational pull on its surface about 20% higher than on
Earth. And cold - as cold as anything that far from the Sun must be. Weinbaum gives a temperature of 10 "degrees
absolute" (i.e., 10 kelvin), a temperature at which almost all gases would
be frozen. Since helium would not be, Weinbaum assumes a thin atmosphere made of this gas. In
fact, Pluto is slightly more hospitable than this, with a mean temperature of
44 kelvin, though with a much thinner atmosphere than Weinbaum guessed at (a maximum of 0.008 millimetres of
mercury compared to his value of 5 millimetres - both so thin as to be
practically un-noticeable to someone from Earth, where the sea-level air
pressure is around 760 mm).
Designing an
aggressive alien life form for such an unpromising environment must have been a
challenge for Weinbaum, which he met by cleverly
introducing a crystalline something on the borderland of the biological and the
purely chemical, like a giant version of a virus. There are many kinds of these "crawlers",
each with a particular kind of food, including sulphur, iron, and aluminium.
Black crawlers eat carbon - and therefore human flesh. The crawlers make a
distinctive crackling rustling sound as they move and, if stepped on, flash
with blue sparks.
Although
no-one's found any giant viruses yet, by a weird coincidence of names,
plutonium does behave a little like a black crawler: if provided with oxygen,
it grows larger and crackles and sparks as parts of it catch fire. And it's
lethal, too.
Frank R. Paul,
one of the greatest science-fiction artists of the 1930s and 1940s, painted a
series of back covers for Fantastic
Adventures pulp magazine. In February 1940, Pluto was the setting, occupied
by creatures that were half-human, half-bat. According to the accompanying
text, while these Plutonians might be highly intelligent, they might also be
mad cannibals, attacking any visitors who approach the machines that provide
them with heat and water from deep inside Pluto.
This last detail
is spot-on : if there ever are any colonists on Pluto, they will have limitless
supplies of both water and heat from underground.
E E "Doc" Smith's book First Lensman (1950) features a
brilliantly weird alien on Pluto, with a constantly shifting appearance
"now spiny, now tentacular, now scaly, now covered with peculiarly
repellent feather-like fronds, each oozing a crimson slime." The alien
actually originates on the extrasolar planet Palain Seven, which is as cold as
Pluto. Palainians can live only on such cold planets, and are (at least)
four-dimensional. They are also telepathic, and this particular alien, most
unusually for the time the book was written, is female.
Larry Niven's 1968 short story
"Wait it out", includes a giant land-dwelling amoeba. Unfortunately,
we don't find anything much out about it and it is only briefly glimpsed.
The brilliant Robert Silverberg
was the first author to introduce an alien with a fully thought-out physiology.
In his 1978 novel World's Fair 1992,
human explorers encounter a crab-like dweller on the shores of Pluto's methane seas, based on carbon chemistry, electrical
energy, superconducting nerves and superfluid-filled veins. The same creatures
appear in Silverberg's short story "Sunrise on Pluto" (1984).
(Superconductivity is a
phenomenon which occurs in many materials when they become sufficiently cold.
All resistance to the flow of electricity ceases, and electrical currents flow
endlessly. Superfluidity is a rarer condition, in which extremely cold liquids
flow, spin or slosh endlessly. Actually, even Pluto is far too hot for any
material to be either superconductive or superfluid, with one exception :
hydrogen sulphide. However, this only becomes a superconductor at extremely
high pressures).
Gregory Benford's 1990 novel Sunborn is the first to be told (partly)
from the point of view of creatures who live on Pluto. The Zand are intelligent
walrus-like creatures who lead a precarious existence in the frigid marshes of
Pluto, their lives focussed on obtaining enough warmth to survive the long
Plutonian nights. There is a great deal more to their story than that, but I
don't want to spoil a book well worth reading.
The latest story of Plutonian
life (as far as I know) is Stephen Baxter's "Gossamer" (1995), which
sounds like a fairy tale in summary : a cobweb spun between Pluto and its
enormous moon Charon. But it's based on an actual feature unique in the Solar
System : there really is a place on Pluto where, if you looked straight up, you
would see a particular location on Charon. And you would always see that same
spot, whatever time of day or day of the year you looked. The Sun and stars and
planets and Pluto's other four moons would spin and wheel around you, but that
one point would remain fixed - so, a rope ladder could join Pluto and Charon.
Or a cobweb. We never meet the web-spinners, but their nests of icy eggs are
found under Pluto's frosty surface.
So what about the real Pluto? Is
life there possible?
Now that the New Horizons spacecraft has visited the dwarf planet, we know that
the answer is yes.
As far as we know there are just
four requirements for life to evolve from chemicals :
carbon, a source of energy, liquid
water and a safe environment.
There is certainly plenty of
carbon on Pluto : we have known that carbon dioxide is present on Pluto since
1992, when the first precise infrared observations were made. Carbon monoxide
was found in 2011. Life on Earth is based on organic molecules, which contain
hydrogen as well as carbon and oxygen, and these are also plentiful on Pluto. Ethane,
the simplest organic chemical, was detected in 1999. This year New Horizons added acetylene and
ethylene to this list.
Energy? The greatest single
discovery made by New Horizons is
that Pluto contains a rich source, originating deep below the surface. In other
worlds, such internal heating is common, the result either of lingering heat
from formation, the tidal effects of orbiting bodies, the decay of radioactive
materials, or collision with meteorites or larger objects. None of these can
fully account for Pluto's sub-surface heat, but the recent discovery of ice volcanoes
show that there is (or was) at least enough underground power to melt parts of
the underground ice layer, providing the third requirement for life. It may be
that there is a whole ocean under Pluto's ice crust, as is known to exist on at
least two moons in the Solar System (Enceladus and Europa).
Whether Plutonian water is to be
found in isolated pockets or global oceans, such environments are safe ones, in
that they are fully shielded from the solar ultraviolet radiation that
illuminates Pluto each day.
Could life really evolve in
Pluto's sunless depths? Possibly : on Earth, there are colonies of living
creatures close to underwater volcanic "springs" called black smokers
which need only the warmth and organic chemicals to survive, and the theory
that all life on Earth evolved from another kind of deep-ocean spring is as well-regarded
as any other.
So, life is possible - but do we
have any direct evidence that it exists? The answer to that is "not
yet." Methane is produced by all sorts of living things, from cows to
cowries and from humans to humming birds (weirdly enough, the majority of the
methane produced naturally on Earth comes from termites). And there is a great
deal - billions of tonnes, probably - of frozen methane on Pluto. The reason
that there have been no headlines screaming LIFE ON PLUTO! is that methane can
be produced in many other ways too, without the involvement of living things.
From a given sample of methane, one can't tell how it was made. But there is
one key difference : when methane is produced by chemical reactions, almost
invariably a lot of other organic chemicals form as by-products. You and I, on
the other hand, while being very efficient methane factories, are not really in
the business of making much else in the way of simple organic chemicals. So, if
it turns out that Pluto is a smorgasbord of organics, the likelihood is that
chemistry is the source. But if there's little but methane, a biological source
would be a distinct possibility. The answer may lie in the reams of data making
their sluggish way across the Solar System from New Horizons. It will be almost a year before all of it reaches
Earth, and probably months more before the process of chemical auditing is
complete. Then we might just see those headlines after all...
So, one more question : if there
really are Plutonians, what might they be like? It depends mainly on how long
they have been there. On Earth, all living things were single-celled for over
three billion years. We don't know if that is typical but it would be risky to
assume that complex creatures could evolve much faster. So, assuming Pluto does
have a sub-surface ocean, has it been there long enough for life (if it
developed there at all) to evolve beyond the simplest structures?
This takes us back to the reason
for the ocean being there at all: Pluto's mysterious internal heat source. In
the absence of evidence of any recent cause, the best guess is that, whatever
that source is, it has been there since Pluto's earliest ages - perhaps four
billion years ago. Plenty of time, therefore, for evolution to run its course.
And the outcome of that
evolution? We can only guess, but we do know that the living things in the
coldest of our own seas are very slow, very old - and very large.
If
you'd like to follow this story over the coming months, keep an eye on http://newhorizonspluto.weebly.com/
And if You'd like to buy Dr Mike Goldsmith's book on Pluto, check here, where I linked it in the first part of this blog:
http://blackberryjuniperandsherbet.blogspot.co.uk/2015/11/guest-post-dr-mike-goldsmith-on-new.html
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