July 1, 2013
Every day, it seems, a new exoplanet is found (or, in the case of Tuesday, scientists discovered three potentially habitable exoplanets orbiting one star). But there are loads of hurdles that we’ll have to clear before we ever have the chance to visit them: the massive doses of radiation that would be absorbed by would-be astronauts, the potential damage caused by interstellar dust and gas to a craft moving at extremely high speeds, and the fact that traveling to even the nearest habitable exoplanet would take almost 12 years in a spacecraft traveling at the speed of light.
The biggest problem, though, might be the enormous amount of energy such a craft would require. How do you fuel a spacecraft for a journey more than 750,000 times farther than the distance between the Earth and the Sun?
Based on our current technology for exploring space and potential future approaches, here’s a rundown of the possible ways of propelling spacecraft.