Dr. Zubrin further argues that even if native microbes have arisen on Mars, for example, the fact that they have not progressed beyond the microbe stage by this point, halfway through the lifetime of the Sun, is a strong indicator that they never will; and that if microbial life exists on Mars, it is likely related to Earth life through a common origin on one of the two planets, which spread to the other as an example of panspermia.
Yet others would see in such an accomplishment the most profound vindication of the divine nature of the human spirit, exercised in its highest form to bring a dead world to life.
"[4] Strong ecocentrists like Richard Sylvan feel there is an intrinsic value to life, and seek to preserve the existence of native lifeforms.
[5]Even this "help" would be seen as a type of terraforming to the strictest of ecocentrists, who would say that all life has the right, in its home biosphere, to evolve at its own pace as well as its own direction, free of any outside interference.
[6] Critics claim this is a form of anti-humanism and they assert that rocks and bacteria can not have rights, nor should the discovery of alien life prevent terraforming from occurring.
Since life on Earth will ultimately be destroyed by planetary impacts or the red giant phase of the Sun, all native species will perish if not allowed to move to other objects.
[citation needed] Some advocates of animal welfare have pointed out the ethical issues associated with spreading Earth-based wild-animal life by terraforming.
In particular, they claim it may be ethically objectionable to bring into existence large numbers of animals that suffer greatly during their often short lives in the wild.
Once the surface is terraformed and people have taken residence there, all the interior material is needed to sustain the maximum gravity potential for those inhabitants.
For example, a written account of some of these debates is available in On to Mars: Colonizing a New World, as a joint article, "Do Indigenous Martian Bacteria have Precedence over Human Exploration?"
177–182) A fairly thorough non-fictional analysis of the ethics of terraforming is also presented under the guise of the fictional Mars trilogy by Kim Stanley Robinson, particularly between the characters Ann Clayborne and Sax Russell, with Clayborne epitomizing an ecocentric ethic of non-interference and Russell embodying the anthropocentric belief in the virtue of terraforming.
The plot of the 1982 film Star Trek II: The Wrath of Khan is based around the use of the so-called "Genesis Device" to create the conditions and organic building-blocks for life on previously lifeless planets.
The ethics of terraforming, as well as deep space colonization, are recurring themes in Firefly, in which they are compared to the issues of expansionism and imperialism in the American Old West.