Turning Mars into a more Earth-like world could irreversibly destroy scientific evidence of its history and of whether life ever existed there. This warning comes from planetologists and ethics specialists from the Netherlands, France and the US in an article published in the journal Eos.
According to one of the authors, Utrecht University planetologist Lonneke Roelofs, Mars can be compared to a vast, almost unread library holding 4.5 billion years of Solar System history. Decades of research have shown that this "library" contains traces of ancient oceans, rivers, volcanic activity and complex organic molecules that may preserve signs of past life.
However, key questions remain unanswered. Why did Mars turn from a potentially habitable world into a cold and dry planet? Could life have arisen there, and has it survived beneath the surface? To begin terraforming - that is, large-scale alteration of the planet's environment for life - before these questions are studied would mean permanently destroying crucial evidence.
Technology is making the scenario increasingly real. Recent work shows that releasing metallic nanoparticles into the Martian atmosphere could raise the surface temperature by at least 30 degrees Celsius within a century. And the development of heavy launch vehicles is making plans to relocate people increasingly plausible.
The authors stress that this is not only about geology. They raise questions of governance and responsibility. Whereas Mars research has traditionally relied on the priorities of the international scientific community, a significant portion of terraforming work is funded from private sources. According to the scientists, planet-scale intervention should require the same public oversight, ethical assessment and international supervision.
The authors therefore call on COSPAR - the Committee on Space Research - to create an expert working group including planetologists, ethics specialists and lawyers. The main thesis of the article: humanity should not decide the future of Mars without first understanding its past.