It isn't yet clear when humans will finally begin spending multiple years (perhaps even decades) in space while constructing space stations, Mars habitats, offworld rovers, and probably a slew of other stunning things I can barely fathom from my cozy Earth couch. What is clear, however, is that our current trajectory suggests such a time will certainly arrive.
Every day, scientists are working hard to make sure we reach the point when our species becomes interplanetary — the era during which we will literally "be" the aliens while exploring the Red Planet or floating alongside Jovian gravity. There's lots to consider. Engineers will need to develop next-generation rockets that can propel astronauts across massive distances in a reasonable time frame. Mission planners will need to learn where on a planet or moon's surface an extraterrestrial society could thrive. Ethicists will need to consider how laws and moral codes would work beyond Earth. Policymakers will need to worry about funding these efforts. Physicists will need to consider how to insert capsules into the orbits of other worlds — orbits they're still just getting hang of.
