What's the Best Ways for Humans to Explore Space?

Should we leave space exploration to robots — or prioritize human spaceflight, making us a multiplanetary species?
Harvard professor Robin Wordsworth, who's researched the evolution and habitability of terrestrial-type planets, shares his thoughts:In space, as on Earth, industrial structures degrade with time, and a truly sustainable life support system must have the capability to rebuild and recycle them. We've only partially solved this problem on Earth, which is why industrial civilizat