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38 JULY-AUGUST 2022 ASTRO PUBLISHING more technos- pheres. Wright and colleagues go even further with the imagin- ing, considering self-replicating technologies that spread across the galaxy regardless of technological life (a nearly cen- tury-old idea, at- tributable to John von Neumann). Aside from the more daring sce- narios, there are already more planets in our own solar system with technosig- nature sources than there are planets charac- terized by biosig- natures. Of the latter there is only one, ours, while in the cal- culation of the former we must add to Earth three other plan- ets − Venus, Mars and Jupiter − which are cur- rently visited by terrestrial technological devices that produce technosignatures (radio waves) certainly weak but theoretically detectable by alien technologies. Wright and colleagues estimate that if spreading technology across the galaxy is part of any civiliza- tion’s evolutionary path, the Drake equation could go as far as under- estimating N(tech) by ten billion times in some extreme scenarios. Obviously, it is not possible to make precise estimates and projections of galactic technosignature abun- dances based on the only example of a technological civilization that we know of. Nevertheless, it is reasonable to ex- pect that the values of N(tech) and N(bio) are strongly conditioned by L t and L b , respectively. Based on our experiences, we can think that L t must be much smaller than L b . In fact, the Earth hosts life that has been producing biosignatures for billions of years, while the first prom- inent technosignatures date back to only a few centuries ago. Since its original formulation, the biggest unknown in the Drake equa- tion has been the duration of a com- municative civilization, paradoxically the only unknown of which we our- selves are the only known example. J ason Wright, is an associate professor of astronomy and astrophysics at The Pennsylvania State University poses for a portrait in the Davey Lab building on the Penn State cam- pus on March 14, 2019. [Eric Firestine, Special to Penn-Live] J acob Haqq-Misra is a Senior Re- search Investigator at Blue Marble Space Institute of Science. [Penn State University] A dam Frank speaks to an audience of Rochester commu- nity members. He was awarded the 2021 Carl Sagan Medal for excellence in public communication in planetary science. [University of Rochester / J. Adam Fenster] tures without technological life and even without a biosphere (Dyson spheres or other megastructures). Another example is a technological civilization that colonizes sterile worlds by creating technospheres. This will likely happen in our own solar system, when humanity has per- manent installations on the Moon, Mars and beyond: a single biosphere (the Earth) in the face of two or