This is an advance summary of a forthcoming article in the Oxford Encyclopedia of Planetary Science. Please check back later for the full article.
Emergence of ballistic missile technology after the Second World War enabled human flight into Earth’s orbit, fueling the imagination of those fascinated with science, technology, exploration, and adventure. The performance of astronauts in the early flights assuaged concerns about the functioning of “the human system” in the absence of normal gravity. However, researchers in space medicine have observed degradation of crews after longer exposure to the space environment and have developed countermeasures for most of them, although significant challenges remain. With the dawn of the 21st century, well-financed and technically competent commercial entities began to provide more affordable alternatives to historically expensive and risk-averse government-funded programs. Space’s growing accessibility has encouraged entrepreneurs to pursue plans for potentially autarkic communities beyond Earth, exploiting natural resources on other worlds. Should such dreams prove to be technically and economically feasible, a new era will open for humanity with concomitant societal issues of a revolutionary nature.