A hard difficulty in Astrobiology is the precise definition of what life is. All living beings have a cellular structure, so it is not possible to have a broader concept of life hence the search for extraterrestrial life is restricted to extraterrestrial cells. Earth is an astronomical rarity because it is difficult for a planet to present liquid water on the surface. Two antagonistic bioethical principles arise: planetary protection and terraforming. Planetary protection is based on the fear of interplanetary cross-infection (...) and possible ecological damages caused by alien living beings. Terraforming is the intention of modifying the environmental conditions of the neighbouring planets in such a way that human colonisation would be possible. The synthesis of this antagonism is ecopoiesis, a concept related to the creation of new ecosystems in other planets. Since all the multicellular biodiversity requires oxygen to survive, only extremophile microorganisms could survive in other planets. So, it could be carried out a simulation of a meteorite by taking to other planets portions of the terrestrial permafrost, or ocean or soil, so that if a single species could grow, a new ecosystem would start, as well as a new Natural History. As a conclusion, ecopoiesis should be the bioethical principle to guide practices and research in Astrobiology. (shrink)