Free Astronomy Magazine September-October 2020

38 SEPTEMBER-OCTOBER 2020 ASTROBIOLOGY therefore with a strong anthropocentric fla- vor. The choice of those targets is based, more or less, on the following essential as- sumptions: regardless of how many forms life can take, it can only be the result of the same physical and chemical principles, as well as any technology used by any civiliza- tion. This means that researchers can take advantage of what has been learned on Earth to imagine what may have happened elsewhere. Despite this logic, focusing the search for technosignatures on solar panels and atmospheric pollutants does not seem to be a winning strategy. It is true that, for each planetary system, its star is the most powerful en- ergy generator, and that har- nessing that energy with photovoltaic systems is an inter- esting possibility. Nonetheless, our own experience as Earth- lings teaches us that this partic- ular way does not appear decisive, as there are more effi- cient alternatives, such as nu- clear fusion and hydrogen combustion. A more advanced civilization than ours might have optimized the collection of stellar energy and dissemi- nated solar panels across a planetary surface, but it could also have chosen more efficient and less bulky solutions. Not even the idea of looking for atmospheric pollutants enjoys great con- sensus, because it would be desirable that any civilization, having reached a certain maturity, would stop polluting the air it breathes. We are all with Frank when he ex- plains that: “Our job is to say, this wave- length band is where you might see certain types of pollutants, this wavelength band is where you would see sunlight reflected off T he Extreme Light Infra- structure for Nu- clear Physics (ELI-NP) is cur- rently the most powerful laser in the world: it can generate light pulses with a power of up to 10 petawatts and keep them gener- ated for a few hours. Despite its extraordinary performance, we are still very far from being able to use laser tech- niques to com- municate with alien civilizations. At most, we can use them to com- municate with satellites, as in the illustration below. [Thales, NASA-JPL]