Interstellar space travel. Fantasy of every five-year-old kid within us. Staple of science fiction serials. Boldly going where nobody has gone before in a really fantastic way. As we grow ever more advanced with our rockets and space probes, the question arises: could we ever hope to colonize the stars? Or, barring that far-flung dream, can we at least send space probes to alien planets, letting them tell us what they see?
The truth is that interstellar travel and exploration is technically possible. There’s no law of physics that outright forbids it. But that doesn’t necessarily make it easy, and it certainly doesn’t mean we’ll achieve it in our lifetimes, let alone this century. Interstellar space travel is a real pain in the neck.
If you’re sufficiently patient, then we’ve already achieved interstellar exploration status. We have several spacecraft on escape trajectories, meaning they’re leaving the solar system and they are never coming back. NASA’s Pioneer missions, the Voyager missions, and most recently New Horizons have all started their long outward journeys. The Voyagers especially are now considered outside the solar system, as defined as the region where the solar wind emanating from the sun gives way to general galactic background particles and dust.