Lithopanspermia is a theory proposing a natural exchange of organisms between solar system bodies as a result of asteroidal or cometary impactors. Research has examined not only the physics of the stages themselves but also the survival probabilities for life in each stage. However, although life is the primary factor of interest in lithopanspermia, this life is mainly treated as a passive cargo. Life, however, does not merely passively receive an onslaught of stress from surroundings; instead, it reacts. Thus, planetary (...) ejection, interplanetary transport, and planetary entry are only the first three factors in the equation. The other factors are the quality, quantity, and evolutionary strategy of the transported organisms. Thus, a reduction in organism quantity in stage 1 might increase organism quality towards a second stress challenge in stage 3. Thus, robustness towards a stressor might in fact be higher in the bacterial population surviving after transport in stage 3 than at the beginning in stage 1. Therefore, the stages of lithopanspermia can themselves facilitate evolutionary processes that enhance the ability of the collected organisms to survive stresses such as pressure and heat shock. Thus, the multiple abiotic pressures that the population encounters through the three stages can potentially lead to very robust bacteria with survival capacities considerably higher than might otherwise be expected. This analysis details an outcome that is possible but probably rare. However, in addition to lithopanspermia, spacecraft mediated panspermia may also exist. The analogous stages in a spacecraft would result in a greater likelihood of increasing the stress tolerance of hitchhiking organisms. Furthermore, missions seeking life elsewhere will frequently be sent to places where the possibility of life as we know it is assumed to exist. Thus, we not only can transport terrestrial organisms to places where they are potentially more likely to survive but also may increase their invasive potential along the way. This analysis highlights further requirements that planetary protection protocols must implement and also provides a framework for analyses of ecological scenarios regarding the transmission of life, natural or artificial, between worlds in a solar system. (shrink)

It is often assumed that the transition between chemical evolution and biological evolution undergoes a smooth process; that once life has arisen, it will automatically ‘flood’ a solar system body. However, there is no a priori reason to assume that a link between them is a given. The fact that both chemical evolution and biological evolution meet in a single point can be critical. Thus, one may ask: can a world’s environment be favourable for chemical evolution but not for biological (...) evolution, or vice versa? This is an important question worth exploration because certain worlds in the solar system in the past seemed to possess the possibility of chemical evolution, while several worlds in the present seem to exhibit such a possibility. Have such solar system bodies thus been, or are, ‘flooded’ by life? Did they possess the opportunity for biological evolution? The answer depends on the very nature of certain conditions under which evolution occurs, which may indicate that a link between chemical evolution and biological evolution is not automatically realised on a habitable solar system body. Thus, these conditions imply that in the emergence and distribution of cellular life, there exists an indeterminacy bottleneck at which chemical evolution and biological evolution meet through a single cell, whose descendants goes ‘information explosive’, ‘entropy implosive’ and ‘habitat expansive’, which determine whether life moves on to new environments. The consequence is that a world's environment can indeed be favourable for biological evolution, but not for chemical evolution. Thus, even if chemical evolution leads to the emergence of a microbial organism in a world, then it is not a given that such a first life form will be subjected to distribution to other environments; and not a given that its existence will continue in the environment it originated in. Thus, the bottleneck may be one of the decisive factors in the differences between habitable and inhabited worlds. (shrink)

Initially, astrobiology subsumed into philosophy. However, philosophy has increasingly subsumed into astrobiology concurrent with it steadily becoming an observational and experimental activity that mainly focuses on the link between life and the cosmos, rather than on extra-terrestrial life per se. However, the steadily increasing probability of locating such extra-terrestrial life and the questions this will lead to might require a refinement of astrobiology, with a bifurcation into astrobiology and astrophilosophy. There are many reasons for the emergence and necessity of astrobiology. (...) One barely realized reason for its emergence, I will argue, is the dawning realization that biology, until now, has been under a geocentric limitation, which has unavoidably pervaded the perception of life. Additionally, as astrobiology can be said to be a long last movement away from this limitation, astrophilosophy represents a movement away from that limitation because philosophy has, strictly speaking, been restrained by the frames for one species, Homo sapiens. Thus, philosophy has, strictly speaking, been anthropomorphic. Thus, when philosophy, like astrobiology, incorporates the Copernican principle, assuming that terrestrial life, and the thinking of Homo sapiens, is not privileged in the universe, astrophilosophy emerges. Astrobiology and astrophilosophy are not competitors but are rather two distinct but complementary activities that address questions with their own well-defined methods and rigor while still informing each other in an inter-dependent manner. Astrophilosophy concerns questions that are philosophical in nature but are procured by an astrobiological perspective. By including scenarios procured by astrobiology, a number of questions regarding value, rights, communication and intelligence that could arise in the interaction between Homo sapiens and extra-terrestrial life can be addressed. (shrink)