Do No Harm to Life on Mars? The Ethical Limits of the ‘Prime Directive’

The solution is to do the hard work of formulating the right principles, at the right level of generality, before circumstances render moral debate irrelevant.

We’re on the hunt for life – what do we do when we find it? NASA/JPL-Caltech/MSSS, CC BY

NASA’s chief scientist recently announced that “…we’re going to have strong indications of life beyond Earth within a decade, and I think we’re going to have definitive evidence within 20 to 30 years.” Such a discovery would clearly rank as one of the most important in human history and immediately open up a series of complex social and moral questions. One of the most profound concerns is about the moral status of extraterrestrial life forms. Since humanities scholars are only just now beginning to think critically about these kinds of post-contact questions, naïve positions are common.

Take Martian life: we don’t know if there is life on Mars, but if it exists, it’s almost certainly microbial and clinging to a precarious existence in subsurface aquifers. It may or may not represent an independent origin – life could have emerged first on Mars and been exported to Earth. But whatever its exact status, the prospect of life on Mars has tempted some scientists to venture out onto moral limbs. Of particular interest is a position I label “Mariomania.”

Should we quarantine Mars?

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Mariomania can be traced back to Carl Sagan, who famously proclaimed,

If there is life on Mars, I believe we should do nothing with Mars. Mars then belongs to the Martians, even if the Martians are only microbes.

Chris McKay, one of NASA’s foremost Mars experts, goes even further to argue that we have an obligation to actively assist Martian life, so that it does not only survives, but flourishes:

… Martian life has rights. It has the right to continue its existence even if its extinction would benefit the biota of Earth. Furthermore, its rights confer upon us the obligation to assist it in obtaining global diversity and stability.

To many people, this position seems noble because it calls for human sacrifice in the service of a moral ideal. But in reality, the Mariomaniac position is far too sweeping to be defensible on either practical or moral grounds.

Streaks down Martian mountains are evidence of liquid water running downhill – and hint at the possibility of life on the planet. Credit: NASA/JPL/University of Arizona, CC BY

A moral hierarchy: Earthlings before Martians?

Suppose in the future we find that:

  1. There is (only) microbial life on Mars.
  2. We have long studied this life, answering our most pressing scientific questions.
  3. It has become feasible to intervene on Mars in some way (for instance, by terraforming or strip mining) that would significantly harm or even destroy the microbes, but would also be of major benefit to humanity.

Mariomaniacs would no doubt rally in opposition to any such intervention under their “Mars for the Martians” banners. From a purely practical point of view, this probably means that we should not explore Mars at all, since it is not possible to do so without a real risk of contamination.

Beyond practicality, a theoretical argument can be made that opposition to intervention might itself be immoral: