Ectogenesis for survival in deep space and deep time: reply to Gale and Wandel

Gale and Wandel (2021) describe my paper in IJA (Edwards, 2021) as having crossed the border of scientific plausibility into the realm of ‘science fiction.’ By science fiction, they presumably mean the ‘bad’ kind based on implausible or unsupported scientific concepts, such as time reversal, multiverses and indeed the warp drives of Star Trek they mention. As my paper is based only on current medical and scientific research, it does not make the transgression they imply. In it, I first reviewed artificial uterus systems and embryo cryopreservation as to whether they could potentially be used in space colonization or in recolonizing Earth after mass extinction events. While complete ectogenesis – the development of early-stage embryos to birth entirely outside the natural womb – is not yet available to serve this purpose, in the near future it likely will be (Bulletti et al., 2011; Räsänen and Smajdor, 2020). To illustrate the power and flexibility of the approach, I then discussed how such systems might be deployed in a comprehensive survival plan to handle a variety of extinction events, ranging from brief events in the very near future to the final, total extinction due to solar expansion (Ward and Brownlee, 2003; Klee, 2017). Gale and Wandel direct their criticisms primarily at these example survival missions, not the feasibility of ectogenesis with cryopreserved embryos per se. On one hand, they argue that near-term extinction events could be better handled by establishing colonies on Mars, on Jupiter’s moons or in O’Neill-type space colonies. Such colonies have dim prospects indeed. Recently it was shown, for example, that insufficient CO2 exists in known reservoirs on Mars to enable terraforming (Jakosky and Edwards, 2018), a sine qua non for Martian colonies. Jupiter’s moon Europa has indeed been proposed as a possible candidate for a space colony (e.g., the Artemis Project), but the extremely harsh radiation environment due to Jupiter’s magnetic storms and the ultra-frigid surface conditions there render such a colony as pure fantasy. Gerard O’Neill’s space colonies – city-sized structures holding up to a million people – rely on such notions as harvesting raw materials for manufacturing from the Moon or asteroids and constructing a totally self-supporting internal ecosystem. Such achievements again go far beyond what is technically feasible in the foreseeable future. Moreover, if by some miracle such colonies were in fact built, it would be Earth which would have to continually sustain them, rather than they protecting us from possible extinction. After a major extinction event, the vital connection with Earth for everything from medicines to spare parts would be lost and the colony would quickly collapse. In the model scheme I proposed, however, smaller spacecraft or space stations orbiting the Earth and carrying just a small number of astronauts/colonists would be one of the first lines of defence in short-duration events. These missions could then be extended using ectogenesis to handle events of progressively larger magnitude and longer duration, by substituting embryos first for some and then finally all of the adult crew members. These orbiting missions together with an interlocking, parallel sequence unfolding in subterranean installations would be the simplest and also the most urgent application of ectogenesis to mass extinction survival, a process I termed Embryo Earth Recolonization (EER). While these EER missions would be the most critical ones in terms of human survival, Gale and Wandel save most of their fire for the far more technically challenging missions of exoplanet colonization, previously termed Embryo Space Colonization (ESC). These missions would be needed to avoid extinction events that render Earth permanently inhospitable to life, including the final one due to solar expansion. They first argue that it would be pointless to send out ESC spacecraft now, with existing methods of propulsion, as they would only be overtaken by later generations of spaceships with faster propulsion. In the first place, missions to exoplanets would most likely not be undertaken until many years of experience had first been gained through designing EER missions for mass extinction survival. By that time significant advances in propulsion systems would presumably have been made. More significantly, an advanced civilization that repeatedly delayed sending out ESC ships could run the risk of being obliterated in an extinction event before any ships were launched. On a deeper level, whether the ships are faster or slower does not really matter. Gale and Wandel’s argument that the mechanical systems on ESC ships could not survive for thousands or millions of years would be true: if the systems were running that whole time. As I