In recent decades, space exploration has advanced by giant steps: there are already man-made probes and robots in different parts of the solar system and even beyond its confines, and in the not too distant future it is likely that manned missions to planets like Mars begin, as well as the extraction of mineral resources on the Moon. These activities can cause irreversible impacts on the extraterrestrial environment: erosion and transformation of the surface and subsoil with mining machines and infrastructures, modification of the atmosphere, as well as introduction of polluting materials and waste … In addition, the possibility of contaminating other planets with terrestrial microorganisms can also hamper space research itself by introducing possible false positives in our search for extraterrestrial life.
For all these reasons, the Committee for Space Research (COSPAR) has planned a series of planetary protection measures that all missions to space must carry out in order to avoid, on the one hand, contamination of the Earth by any type of extraterrestrial life. , and on the other, the introduction of terrestrial microorganisms on other planets. We have talked about all this in this interview with Carlos Briones, CSIC researcher at the Center for Astrobiology (INTA-CSIC) and author of the book Are we alone? In search of other lives in the cosmos (Critical Ed. 2020).
In your book you dedicate a very broad chapter to planetary protection and the importance of avoiding contaminating other planets or satellites with terrestrial microorganisms, although this is a complex task. For example, thinking of Mars, where right now there are several rovers circulating simultaneously, is it possible that this terrestrial contamination has already occurred? How could it interfere with the search for life?
Surely it has already happened, after all, we have been sending missions to the surface of Mars for several decades. What planetary protection tells us is that we have to clean and sterilize everything that we send out, but total sterilization is never complete . It is impossible for something assembled on Earth to come out completely sterile: its surfaces are full of microorganisms.
In the missions, different levels of cleaning are determined depending on each part of the rover, for example Perseverance or Zhurong, which are the newcomers, have the wheels much more sterilized than the mast with the cameras, which is not supposed to be in contact with the Martian surface . But of course, if they are missions like these two in which everything goes well, fine, but if something goes wrong and the rover crashes and creates a crater in which all the materials end up mixing, then things change.
Ultimately, it is quite likely that terrestrial organisms have already reached Mars, but the question is whether they have survived there . The journey itself is very hard, and once on Mars they continue to receive a lot of radiation and in principle there is no water on the surface, there could be at some times of the year and in very specific areas, but nothing more. So, yes, there could be small oases of terrestrial life on Mars. Not likely, but not impossible.
Sterilization and cleaning measures to comply with planetary protection protocols greatly increase the cost of missions. What is your position on this? Are we overshooting or falling short of planetary protection?
In principle, I would maintain the restrictions that exist right now, especially since we are in the phase of not knowing if there is extraterrestrial life out there. It is very important not to introduce false positives: it would not make sense to detect a life on Mars that is actually of terrestrial origin. It is true that planetary protection measures raise the cost of missions, but you have to do it right. We cannot afford to pollute other planets, it would not be ethical.
At the same time, there is the issue of pressure from aerospace companies to make profitable their investments in missions: maybe it is necessary to exploit the mining resources of Mars, as it will undoubtedly be done soon on the Moon, and in that case what? we make? How do we send groups of miners to maintain the necessary sterility? It is a very complex problem.
Of course, this is a tricky issue because in addition to the interference with the research itself, it raises questions even of an ethical nature: what right do we have to invade Mars or other celestial bodies, especially if we do not know if there is life there?
In his mythical work Cosmos , Carl Sagan said: “If there is life on Mars, I think we shouldn’t do anything with the planet. Mars would then belong to the Martians, even if the Martians were only microbes ”. I agree: if a planet has been colonized by some kind of life we have to preserve it and keep it intact. We already know what has happened on Earth when we have entered certain intact ecosystems and we have loaded their biodiversity, so we should try to ensure that this does not happen in other places, I do not care about the subsoil of Mars than the waters below it. ice of Europe or light it up. It is clear that it is very difficult to investigate without altering, but it is what should be done, and the first measure is to avoid bringing life from Earth.
And what will happen if manned travel from Earth becomes widespread? Will it be necessary to reach some type of legislation or international agreement such as the Antarctic Treaty?
Of course, it is going to be very complicated. You can sterilize a rover but not a human body, we are constant dispersers of microbes. I believe that when the manned missions arrive, the surface or interior of those places will probably be irreversibly altered. On the Moon, mining is going to alter the landscape and the distribution of resources, and obviously many geoethical problems arise, and which will eventually be bioethical if mining is generalized on habitable planets like Mars. It takes a lot of legislation and the COSPAR to make decisive decisions to protect the integrity of these places. It is necessary to regulate in some way how these exploitations will be made and to whom those resources will belong, because in principle neither the Moon nor Mars belong to any country or company. Whose will they be? Who comes first? Are we going to repeat our country and border madness elsewhere? Has no sense.
The Antarctic Treaty, in fact, is proposed as a model to do something similar with Mars, to establish ways that allow us to interact there peacefully with the sole scientific interest of exploring and nothing else. But it is that on Earth we are as we are, and as soon as we see resources of some kind we try to deplete them. In short, I do not know what will happen, but what has to happen we will surely see, because it will probably be in a couple of decades.
A slightly more philosophical issue: when one starts looking for life abroad, one realizes how complex and fascinating the life we have here on Earth is, has the fact of studying these questions allowed you to value more the need? to protect the biodiversity of our planet?
Undoubtedly. Astrobiology teaches you how delicate the balance of life is and what allows us to be here. Earth is not a special planet geologically or chemically, but from what we know so far, it is unique biologically. This makes you understand the need to preserve life and ecosystems, to limit the outrageous consumption of resources and to alter as little as possible. Ecological awareness is greatly enhanced when you are studying the possibility of life outside of Earth.
