The journey through the twenty-three preceding chapters has taken us across the spectrum of space science and its application in space technology and to living and working in space, as we understand them today, in 2010. It has been a mere 211 years since Jefferson wrote his prophetic words, and while the storehouse of our knowledge has advanced immeasurably since then, and humanity has since constructed a globalized, industrialized civilization of unprecedented power and scope, it is equally obvious that even today there remains a great deal that we have yet to discover. Among the unknowns of interest to us in this book is how we will ultimately live and work in space.