give off oxygen. Within several decades there might be soil. But the whole operation could take many centuries. For example, lichens have a very slow growth rate and are not suitable for fast oxygen production. If blue-green algae covered one quarter of the Martian surface it would take about 7,000 years to produce 5mb of oxygen; the minimum for human breathing at this rate would take 140,000 years (Smith, 1989: 124). The best solution to this problem lies in further developments in genetically altered plants which could speed up oxygen production.
There is a possibility that bacteriological research could contribute to the terraforming of Mars. Following the claim that bacteria may have once existed on Mars, various experiments were conducted at the end of the twentieth century to replicate a Martian environment and test its potential to support life. Now the closest terrestrial equivalent to Martian soil is volcanic ash. So experiments were conducted to see if ‘methanogen’ bacteria can survive in ash from a Hawaiian volcano. Timothy Kral and his colleague, Curtis Bakkum, grew four species of methanogens in conditions resembling the environment three kilometres beneath the Martian surface (Coghlan, 1999a: 14). It might be speculated that if methanogens can survive on Mars they could be employed in a terraforming project whereby these bacteria would release methane to create a greenhouse effect, warming the planet and releasing its frozen water.
A rather eccentric suggestion for the greening of Mars is to bomb Mars with Trident missiles containing CFC gases. Objectors to this proposal draw attention to technological problems, one of which is that launching the number of rockets, large enough to carry a sufficient load to ‘green’ Mars, would have an adverse effect on the Earth’s atmosphere. There is also the objection that some of the suggested methods of terraforming Mars might dry up water reserves quicker that the present natural processes have done.
In the course of terraforming Mars many problems would have to be over-come, but no laws of nature would have to be breached and it would not require any as yet unheard of developments in technology. However, the resourcing plans for colonization are daunting. Governments and large investors have great problems in resourcing large-scale projects lasting more than one generation, as can be seen with reference to a ten-year project like the Channel Tunnel, which has obvious potential benefits.
Venus
Venus is roughly the same size as Earth but different in three important respects: first, its atmosphere is 100 times thicker, and is composed primarily of CO2, with a high surface temperature due to the greenhouse effect. CO2 is more efficient in letting heat in than letting it escape. Second, Venus does not have global plate tectonics like Earth, which means that its interior heat source produces more catastrophic volcanic activity. Third, there is no surface water; all the Venusian water is in its atmosphere.
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The task of terraforming Venus is very daunting. The first objective would be to produce a more clement temperature. With sufficient technical skills it might be possible to move asteroids into orbits that would result in collisions, where each impact would release some of the atmosphere from the planet. The problem with this suggestion is that even if there were a sufficient number of available asteroids the impact would devastate large amounts of the planet’s surface.
Other proposals for the reduction of the Venusian temperature include the use of a gigantic sunshade to reduce solar energy, or to add dust particles to the upper atmosphere to absorb or reflect heat from the Sun. Even more exotic are proposals to send genetically modified microbes that can convert CO2 into carbohydrates. But even if all of these proposals were feasible, the terraforming of Venus would take thousands of years, which means that large-scale financial support for such a venture would be unlikely.
Other locations?
There are proposals for terraforming Io, the innermost of the Galilean moons of Jupiter. According to James Oberg (1995: 86–91), it has several advantages over other candidates. Foremost is its source of internal heat generation caused by tidal stresses induced by Jupiter. However, among the drawbacks is the deadly radiation belt which surrounds Jupiter. Also, Io has no water and no atmosphere, but the radiation belt could be decontaminated by pulverizing one or more of the smaller moons, says Oberg, thus creating a ring of rocky debris which would provide protection from Jupiter’s radiation. Water could be imported from Io’s icy companions, Ganymede and Callisto. According to Oberg (1995: 89), Io could be habitable by the end of the next century.
Ethical aspects of terraforming
At present terraforming projects are unfeasible, but in the long term they might fall within the scope of possible programmes. In which case, the ethical issues they raise will require elaboration. The ethical arguments for and against terraforming other planets can be summarized as follows.
In favour of terraforming
1. A terraformed planet would provide a base for astronauts, scientists and colonists; a possible new frontier or refuge from catastrophic events on Earth, such as natural calamities or war. Mars could support human settle-ments. Although smaller than Earth, it has much land space. A new frontier might generate new world values, such as cooperation, and provide a point for criticism of old world values. From a social perspective there is a chance
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