Feature

Martians Beware!

Any lifeforms on Mars could be at risk if we fail to follow Star Trek's Prime Directive.

Alan Marshall

Aboard the Starship Enterprise there exists a cardinal rule governing the actions of the Star Trek crew as it gallivants around the galaxy, boldly going where no one has gone before. Labelled the "Prime Directive", this ethical rule states that humans shall not interfere with any alien life encountered lest the aliens, and their social or physical environment, be destroyed or irrevocably damaged.

The most notable medium of such interference is through the action of invasive microorganisms. The writers of Star Trek have invented a convenient piece of technology to handle such interplanetary transfer of germs. When beaming off to a new planet, "biofilters" installed in the Enterprise's transporter supposedly filter out germs accompanying the crew.

Twentieth-century space exploration has no such biofilter technology and if present proposals to explore and colonise the planet Mars go ahead, humans may spread the spores of destruction for countless extraterrestrial species. This would constitute a failing of the Prime Directive at its first test.

The scientific and astronautic community has looked into the problem of the contamination of other worlds with Earth microbes, and there are policies in place to ensure microbial stowaways are not carried throughout the solar system aboard robotic probes. However, with human exploration, prevention of contamination would be impossible. There is little chance of sterilising a human to the same degree of decontamination as is possible with a robot.

Mars Beckons

The favoured planet when it comes to human exploration of the solar system is Mars. Ever since the completion of the Apollo lunar landings, Mars has been the prime candidate for both the US and Russian assault on the space frontier. What may be the consequences of such human endeavours for any native Martian lifeform?

The question is null and void to many space exploration advocates, since they feel that the Viking project of the 1970s proved Mars to be devoid of life. But it did no such thing. It merely established that there were no Earth-like lifeforms located in the two particular sites that the Viking Landers visited. Viking project scientists still debate the efficacy of the Viking life-detection experiments and whether some form of life was actually found.

Having said this though, it is certainly the pervading feeling amongst the science and astronautics communities that Mars is lifeless. There exist important extra-scientific factors that can contribute to an explanation of why there is this unwillingness to admit the possibility of life on Mars.

The legacy of Percival Lowell -- and his fanciful Martian canals -- sets a historical precedent that encourages an ultra-conservative approach when it comes to Martian biology. Since then, progressively more modest theories of Martian life have been put forward from Martian civilisations, to forested plains, through to desert-type vegetation communities. All of these have successively succumbed to oblivion as our knowledge of Mars' physical environment has increased. Few scientists wish to be seen as "bio-optimists" since history dictates that you are going to get it wrong.

Granted that a widespread biota on Mars is absent, the possibility of extant microfloral communities does exist. Currently there are numerous scientists around the world presenting credible models of possible Martian life. Lynn Rothschild of NASA has proposed a model of Martian life similar to those microbial communities found in the evaporitic deposits of Baja Californian salt pans. Scientists at Russia's Institute of Soil Science have put forward a model of extant Martian life based on nitrifying bacteria found in the Siberian Arctic. The algae that live inside the rocks of the Antarctic dry valleys also serve as examples of what life on Mars may be like.

Foreign Colonists

If there is life on Mars, why should it be bothered by the introduction of terrestrial microbes? New Zealanders are particularly aware of the potential of invasive species in affecting the indigenous biota of an ecological community. Just as in New Zealand, an endemic Martian ecology may be intensely susceptible to invasion by foreign species. Studies aboard the Space Shuttle and other spacecraft have shown that terrestrial microbes are enviably able to tolerate the extremes of space environments. If a microbe finds its way to Mars via human exploration, it may impinge on the native microbial species in a number of ways:

• an invasive microbe may produce substances poisonous to native species (antibiosis)
• an invasive microbe may predate upon a native species to obtain its carbon, nitrogen, water (phagocytosis)
• an invasive microbe may invade the cells of a native species to facilitate its own reproduction (infection)
• invasive microbes may out-compete native species for scarce resources such as water, light, shade or space (competitive exclusion)
• an invasive microbe may alter the Martian environment in such a way that the change kills the native species

While infection may be unlikely, as it relies on the specificity of a host-parasite relationship arrived at through a co-evolutionary heritage, the other threats are real.

That the above threats can be contained at the point of initial contamination may be a false expectation. Bacterial and fungal spores may be carried thousands of kilometres by the episodic Martian dust storms. And the wider the exploration activities of humans the wider will be the dissemination of terrestrial organisms. In the event of human colonisation of Mars, no indigenous microbial community may survive untouched, particularly when human pollutants become widespread as that might work synergistically to enhance the invasion by Earth microbes. Putting a fence around a reservation is even less likely to work on Mars than it does on Earth.

On the most Mars-like environment on Earth -- the dry inland valleys of Antarctica -- introduced microbes from scientific personnel have commonly grown and reproduced more rapidly and at lower temperatures than the indigenous Antarctic microbes. Scientific explorers on Mars (or for that matter in Antarctica) must tread warily in case their explorations impinge on the integrity of a microbial ecosystem or induce extinction of microbial species.

So there may be microbial life of Mars. And so human activities have the capacity to destroy such life. So what? We spend a large of time and resources trying to rid ourselves of microbes on Earth, why should we let microbes stand in the way of human space exploration? Humans are humans and microbes are...well...just invisible bugs.

This is precisely the sort of attitude Europeans have had in the past to indigenous human populations during their colonial expansion. Indigenous peoples were thought of as being some sort of sub-level of humans who were not worthy of the moral considerability afforded to Europeans. We have just about got over such brash racism (at least theoretically), but now the environmental movement challenges us to reject anthropocentrism. Just as the white man is not the measure of all things human, so humanity is not the measure of all things living.

Biotic Egalitarianism

An ethic of biotic egalitarianism is emerging in environmentalism and it suggests that humans and microbes exist side by side on the ladder of moral considerability. It might be difficult contemplating such a perspective. Certainly microbes are not cuddly like koalas, nor graceful like orca or enchanting like kauri. But these are human ascribed qualities. And they often fall short of some of the less aesthetic species, who have as much right to an existence as humans and the lifeforms we regard as beautiful.

If you choose not to buy into such biotic egalitarianism, you may still wish to protect Martian life for what it could mean for science. Discovering extraterrestrial life would be a monumental moment in scientific advancement, and to jeopardise such an opportunity by putting humans on Mars would be to blaspheme the spirit of science. Thus human exploration of Mars can jolly well wait till we have thoroughly explored Mars with decontaminated robotic probes so as to determine whether Mars has life. But there is a paradox here. It is probable that robotic probes will only ever deliver ambiguous results with regards to Martian biology. To really find out if there is life on Mars, humans (and their accompanying microbiota) have to go there to do it, thus endangering the very life they seek to discover.

That Martian life is valuable for scientific reasons will to some extent ensure a preservationist attitude to Mars. But more than that, Martian life is intrinsically valuable. Martian microbes have no obligation to contribute to human scientific knowledge, and the search for such knowledge should not compromise the intrinsic value of Martian life.

Many of those people that propose to expand humanity into space do so on the enticing notion that it is a natural and inevitable process. Just as a tree casts forth its seeds to colonise a new piece of ground, so humans are seeking to expand their ecological domain. Such a naturalistic interpretation evades the fact that space expansion is a social phenomenon, not a biological one.

A dispersing seed acts according to genetically and ecologically prescribed rules which have been arrived at through millions of years of biological evolution. The entities taking part in space expansion (namely nations, space agencies and private aerospace companies) are social entities that act according to social forces arrived at through the course of social, political and economic history (processes quite different to biological evolution). Far from being in our genes, twentieth-century space exploration is a demonstrable phenomenon of Cold War history. The US Apollo project was initiated as a nationalistic response to the perceived strategic threat posed by the Soviet Union's newly established rocket potential. I doubt strongly that Neil Armstrong or Buzz Aldrin have specific genes coding for space exploration in their respective genomes.

The seed dispersal analogy argues that interplanetary expansion by humans is a natural phenomenon, just as it is natural for a seed to colonise a new land mass. However, a human embryo is not anatomically adapted to using space as a medium of dispersal, as a plant embryo (seed) is adapted to using wind or the feathers of a migratory bird as a dispersal medium. Nor does a human embryo happen to spontaneously fall into space and commence to colonise another planet (in anything other than the metaphysical sense).

Space exploration is a romantic pursuit. But we should not let the romance of human activities in space blind us to the possibility that we are endangering the survival of extraterrestrial species. Next time you chance upon Captain Kirk and his gallant crew zooming from planet to planet in the corner of your living room, you may stop to ponder how many extinct species he may have left in his wake, and whether such explorations of destruction are to be initiated in your lifetime.

Alan Marshall is studying at Massey University, where he has been researching into the social and environmental implications of space development, at the Institute of Developmental Studies.

Alan Marshall is studying at Massey University, where he has been researching into the social and environmental implications of space development, at the Institute of Developmental Studies.