INTRODUCTION
The question “are we alone” is becoming increasingly answerable with scientific
advances in the field of astrobiology. While there is no evidence that the laws of nature
say that the development of life is inevitable, recent discoveries in our own solar system
and even on our own planet indicate that life is not as rare as it was once thought to be.
American Paleontologist George Gayland Simpson once described the search to find life
elsewhere in the universe as “a gamble against the most adverse of odds” [1]. The
sentiment was echoed in the 1960s by much of the biological community. The French
biologist Jacque Monod, who subscribed to the orthodox position of his time, remarked
“life on earth emerged by pure chance out of the unfeeling immensity of the universe.” [1]
Since then, the general attitude has shifted toward a belief that life is a “cosmic
imperative” that will emerge when the right conditions are in place. Still, this feeling is
not based on much hard evidence. Biochemists are still unable to synthesize amino
acids—the building blocks of life—in a laboratory setting. The believed conditions of
primeval earth had amino acids. In 1953 amino acids were created for the first time in a
laboratory. [1] Since then, they have been found frequently on meteorites. But their
presence is not enough in itself to conclude life exists elsewhere. It requires more than
just a random collection of amino acids to make a protein, which are an elaborate
configuration capable of a specific function. To link the acids together in the right order
is an uphill process. The cells’ DNA is responsible for encoding the process so it
happens in the correct sequence. Otherwise, it happens by pure luck. To translate the
four-letter alphabet of DNA into the twenty-letter system used by proteins, all life on
earth uses the same code. Scientists try to find out why this encoding emerged. How did
the seemingly “stupid” atoms write their own genetic software? The odds against
random chemical mixture just happening to order the appropriate molecules in the correct
arrangement are incredibly huge. If life arises by pure chance, it will have happened just
once in the observable universe. [1] So-called biological determinists believe that the
shuffling arose from the laws of nature. They observe that there is a natural tendency for
amino acids to link up in precisely the right order and that there is a built-in bias in nature
to create life. This assertion would imply that the laws of physic and chemistry contain a
blueprint for life. [1] But if this is the case, why is it so hard to find? Recent discoveries
suggest that it my not be.
THE RECENT CASE FOR LIFE
Those that hold the view that life across the universe is unavoidable, like those at
NASA or the SETI Institute in California, continue to sweep the skies for signs. Lately,
evidence has amounted that life in our solar system might not be confined to Earth.
The planet Venus was long thought not to support life because of its extreme
temperatures and acidic surface. However at fifty kilometers above the Venusian surface,
conditions are relatively hospitable with the temperature at 700C and a pressure of one
atmosphere. [2] Dirke Schulze-Makuche from the University of Texas El Paso looked at
existing date from the Russian Venera Space Probe and US Pioneer Venus and Magellan
Probes and noticed some peculiar things about the chemical composition of the
atmosphere. Firstly, he claims, solar radiation and lighting should produce large
quantities of carbon monoxide. But instead, this chemical is scarce, as though something
in the atmosphere is removing it. The probes also discovered hydrogen sulphide and
sulphur dioxide coexisting in the same places. These gases react with each other are
never found together unless something is producing them. Even more mysterious is the
presence of carbonyl sulphide. It is difficult to produce this chemical inorganically and is
therefore often considered an unambiguous indicator of biological activity. [2] While it
may be possible to produce it in a non-biological way, a catalyst is needed to do so. On
earth, the catalysts are microbes. Schulze-Makuche theorizes that bugs living in the
Venusian clouds could be combining sulphur dioxide with carbon monoxide and possibly
hydrogen to produce either hydrogen sulphide or carbonyl sulphide in a metabolism
similar to that of some early Earth bugs using UV light from the sun as an energy source.
Not everyone agrees. For life to exist, volumes, not just tiny atmospheric droplets of
water, are needed. [2] But there is chemical evidence that Venus was once much cooler
and had oceans. If this were the case then, Schulze-Makuche claims, life could have
started there and later found refuge in stable niches in the atmosphere once the
greenhouse effect began.
New findings also suggest that tiny extraterrestrial microbes might penetrate the
Earth’s own atmosphere all the time. Two species of bacteria, B. simplex and S. pasteuri,
along with one fungus, E. albus, have been collected by a weather balloon cruising at
41,000 metres over southern India. [3] The organisms are often found in soil and
vegetation on Earth. One explanation for their finding is that they were carried up into
the atmosphere by wind currents. However, the type of turbulent weather needed to carry
them usually acts below 17,000 metres. [3] Volcanic eruptions are known to push matter
up into the atmosphere, but there were none in the months preceding the collection.
Given the density of the sample, it would have returned to the earth under gravity long
before it was collected. If the sample is truly alien, it is estimated that a ton of the
bacteria falls on the Earth each year.
THE VALUE OF THESE DISCOVERIES
Though these recent findings provide no conclusive evidence for the existence of
extraterrestrial life, they are nevertheless compelling because of the prospects they
introduce for future investigation. What the crop of current evidence suggests is that the
circumstances required for the development of life exist everywhere. This tends to build
upon the increasingly popular belief that the formation of life is not uncommon, but
rather permeates the universe—which statement seems to imply that the significance of
any scientific discovery rests upon its ability to confirm a popular belief, whether it is
supported or not by evidence. But the question of life in space first arose not from a
scientific observation that caused scientists to look for it, but rather from the at once
breathtaking and intriguing possibility that in the vast universe we might have
counterparts. This is what drives the search. Much of the Hollywood film industry
assumes that life exists elsewhere and this feeling is fueled by a public who flocks to see
movies like ET. Science fiction film genre thrives in a mutually dependant relationship
between the film studio and the audience. The studio sustains itself by giving the
audience what it wants to see: aliens. If this phenomenon says anything about human
nature it is that we have a fundamental desire to believe in a universe with other life, as if
to mitigate against fears that we are alone.
The recent findings on Venus and in the upper stratosphere are encouraging steps
in the field of astrobiology. The former is to be followed up with two missions to Venus:
one headed by the European Space Agency which will investigate the planet’s
atmosphere and is due for launch in 2005, and the other by the Swedish Space Agency
who hopes an international partnership will return a sample of the Venusian atmosphere
by the end of the decade.
WORKS CITED
[1] Davies, Paul. “Life Force.” New Scientist. 18 Sep., 1999.
[2] Clark, Stuart. “Venus A Haven for Life?” New Scientist. 28 Sep., 2002
[3] Hogan, Jenny. “Microbes From Edge of Space Revived.” New Scientist. 17 Dec.,
2002.