The following essay is being published in conjunction with the “(In)hospitable Space Conference” which explores the human dimensions of space exploration and is cosponsored between the English Department of Carnegie Mellon University, the Society for Social and Conceptual Issues in Astrobiology, and the European Astrobiology Institute.
Astrobiology is often presented as the science that studies the possibility of life in the universe. That definition is correct, but it remains incomplete if we do not recognize that the question of extraterrestrial life is not only scientific. Asking whether there is life beyond Earth also means asking what we would do if we found it, how we should act toward it, and what responsibilities humanity would have when intervening in other worlds. For this reason, astrobiology cannot be understood only as a discipline of the laboratory, the telescope, or the space mission. It is also an invitation to think about our place in the cosmos.
From this perspective, astrobioethics emerges. By this term, I refer to the ethical reflection on the problems that arise when humanity searches for, finds, or may affect extraterrestrial forms of life, or environments where such life could have existed or could exist. Astrobioethics does not wait until we find life beyond Earth before beginning to think. On the contrary, it anticipates possible scenarios, because when the discovery happens, if it happens, decisions will not be made under ideal conditions, but under scientific, political, economic, and media pressure.
Astrobiology is transdisciplinary because it brings together the natural sciences, the social sciences, and the humanities. Biology, chemistry, astronomy, and geology help us search for conditions of habitability, biomarkers, extreme environments, and possible traces of life. But philosophy, ethics, law, education, and the social sciences allow us to think about what those discoveries mean, how to communicate them, how to regulate them, and how to assume their consequences. No single discipline, by itself, can fully answer the question of life in the universe.
The natural sciences work with empirical evidence. They observe, measure, experiment, and seek to confirm or refute hypotheses. If we speak of extraterrestrial life, it is not enough to imagine it: we would need to find sufficiently solid direct or indirect evidence. Philosophy and ethics, however, work differently. They do not seek to measure a molecule or detect a signal, but to clarify concepts, evaluate arguments, formulate principles, and anticipate dilemmas. They do not replace science, but they allow us to think about its implications.
This is important because ethics does not need to wait for definitive proof of extraterrestrial life to ask what we should do. We can imagine reasonable scenarios. For example, if microbial life were someday confirmed on Mars, Europa, or Enceladus, would we have the right to intervene in those environments without limits? Could we contaminate those places with terrestrial microorganisms? Would it be acceptable to destroy an extraterrestrial form of life simply because it does not feel pain or think?
Most living beings on Earth are microscopic. Therefore, if we find life beyond our planet, it is reasonable to think that it could be microbial life. That life would have no consciousness, language, or ability to claim rights. However, its value would be extraordinary: it would represent a second expression of life in the universe. It would not simply be “another bacterium,” but possible evidence that life is not an accident exclusive to Earth.
Here a central idea appears: humanity would have to learn to care for forms of life that cannot care for themselves. Charles Cockell uses the concept of teloempathy to refer to the ability to recognize the interests of other extraterrestrial forms of life, especially if they were unable to defend themselves. In this sense, if we found microbial life on another world, we would be its guardians. If we do not protect it, who will?
Astrobioethics can be organized into three major axes: legal, moral, and social.
The legal axis refers to the norms that should regulate human activity in space. This includes states, space agencies, private companies, and any actor that may intervene in environments of astrobiological value. A space mission can have astrobiological consequences even if its main objective is not to search for life. A mining company, a tourist mission, a human base, or a drilling operation could alter environments of enormous scientific value.
The 1967 Outer Space Treaty was fundamental in establishing that space must be used for peaceful purposes, for the benefit of all humanity, and without national appropriation of the Moon or other celestial bodies. However, that legal framework does not develop with sufficient clarity what should happen if a mission puts at risk an extraterrestrial form of life, ancient biological evidence, or an environment with conditions favorable for life. That gap is concerning.
Today, space exploration no longer depends only on states. Private companies are increasingly involved in space activities. Therefore, it is not enough to say that a mission is not searching for extraterrestrial life. If it can contaminate, alter, or destroy an environment relevant to astrobiology, it should be subject to international evaluation and supervision. Astrobiological protection should not depend on the goodwill of space actors.
We must also think about astrobiologically sensitive zones. Some zones could contain water, organic compounds, or energy sources. Others could have hosted life in the past. Others could contain present life. Waiting until life is confirmed before protecting an environment could be too late. A principle of astrobiological precaution should be applied: when there is a reasonable possibility of biological, scientific, or existential value, we must act with prudence.
This also implies distinguishing between forward contamination and backward contamination. Forward contamination occurs when we take terrestrial microorganisms to another world and alter its natural state. Backward contamination occurs when we bring extraterrestrial samples to Earth without fully knowing their effects. Both cases require strict protocols because they compromise both the integrity of other worlds and the safety of our own biosphere.
The moral axis goes beyond the law. Even if there were no norm obligating us, we could still have ethical responsibilities. If an extraterrestrial form of life were sentient, we could apply principles similar to those we use to defend animals: avoiding suffering, recognizing interests, and not causing unjustified harm. But if it were microbial life, the argument would be different. We would not protect it because it suffers, but because it represents an independent form of life in the cosmos.
Not all scenarios raise the same dilemmas. Finding microbial fossils is not the same as finding an active biosphere. Detecting a distant technological signal is not the same as establishing communication with an extraterrestrial civilization. Nor would it be the same to encounter a more advanced civilization as to encounter a less developed one. In each case, human responsibility would change.
If we found active and defenseless microbial life, the priority would be to avoid its contamination, destruction, or irresponsible use. If we found fossil remains, the duty would be to preserve unique evidence about the history of life in the universe. If we detected a technosignature, we would have to decide how to interpret it, who should communicate it, and what social consequences it could have. If we entered into contact with a civilization, questions would arise about representation, communication, power, autonomy, and prudence.
The social axis is equally important. Finding life beyond Earth would not be only a scientific discovery. It would be a cultural, philosophical, religious, educational, and political event. The question “Are we alone?” does not belong only to astronomy. It also touches our identity as a species. It would change the way we understand life, humanity, and our place in the universe.
The idea of inhabited worlds is not new. Already in antiquity, some philosophers imagined the possibility of multiple worlds. Later, Giordano Bruno defended a vision of an infinite universe with countless worlds. What is interesting is that the same intuition can be received in different ways depending on the period and the culture. For some, it may be an expansion of knowledge; for others, a threat to their beliefs.
That is why scientific communication is part of astrobioethical responsibility. When speaking about extraterrestrial life, anomalous signals, biomarkers, or interstellar objects, society can become excited very quickly. Public imagination often moves faster than the evidence. For this reason, scientists and science communicators must communicate with prudence. A hypothesis must be presented as a hypothesis. A possibility must not be communicated as if it were a conclusion.
History shows that astronomical phenomena can feed extreme interpretations. The case of Heaven’s Gate, associated with comet Hale-Bopp in 1997, reminds us that narratives about the cosmos can have dangerous social effects when uncertainty is transformed into suggestive certainty. This does not mean we should stop talking about these topics, but that we should do so with responsibility, clarity, and proportion.
Astrobioethics also has enormous educational value. It allows students to understand how different areas of knowledge connect around one great common question: life in the universe. Astrobiology can integrate scientific experimentation, technological design, data analysis, philosophy, ethics, and social reflection. In projects such as stratospheric balloons with an astrobiological focus, students learn not only science, but also collaboration, critical thinking, and responsibility toward extreme environments that serve as analogues of other worlds.
All of this leads us to a broader vision: astrobiocentrism. Just as anthropocentrism places the human being at the center, and biocentrism expands moral consideration toward terrestrial life, astrobiocentrism proposes thinking of life as a cosmic possibility. It is not about claiming that every extraterrestrial form of life has the same value as a human life. Nor is it about paralyzing space exploration. It is about recognizing that other worlds should not be seen only as resources, laboratories, or territories available for human expansion.
Astrobiocentrism demands that humanity rise to the level of its technological power. If we can reach Mars, send probes to icy moons, study exoplanets, or modify extraterrestrial environments, then we must also ask what limits we should respect. The technical capacity to do something does not automatically amount to moral authorization to do it.
The ethical history of humanity has progressively expanded its circles of consideration: from the tribe to the city, from the nation to humanity, from humans to animals and ecosystems. The space age forces us to ask whether that circle can expand even further. Perhaps our responsibility does not end on Earth. Maybe the search for life in the universe also forces us to build an ethics larger than our own planet.
Astrobioethics invites us to think before acting. It reminds us that space exploration is not only a technical adventure, but also a moral test. If someday we find life beyond Earth, even in its simplest form, that discovery will not only change science. It will also force us to change the way we understand human responsibility. The question is not only whether we can go farther, but under what principles we want to do so.
