To reach Alpha Centauri within a human lifespan requires a spacecraft traveling one-thousand times faster than Voyager. Increasing speed by a factor of a thousand requires at least a million times more energy. The challenge is even greater for reaching habitable planets. Although no Earth-like planets have been discovered, provisional estimates suggest that they will be at least five times farther than Alpha Centauri (20-ly – 200-ly). Extraterrestrial intelligence, if there is any, might be over a hundred times farther than Alpha Centauri (500-ly – 6000-ly). [Read more about destination estimates] Numerous ideas have been suggested for how to get there. With many facts still uncertain, it is too early to determine which idea is “best.” At this stage, the choices are subjective, and can be grouped into these three perspectives: technological, human survival, and physics.