Fast, routine travel from one star to another has long been astaple of science fiction. However, interstellar travel would be extremely difficult withcurrent technologies because of the tremendous distances to even the nearest stars, the amount of energy required, and the constraints imposed by the laws of physics. Although there are no specific plans in place for interstellar missions, and there are only a few spacecraft that are heading into interstellar space, a number of concepts for human and robotic spacecraft that could travel from this solar system to another star have been developed.

It took Voyager 2 twelve years to travel from Earth to Neptune (pictured). Current technology does not allow for the speeds needed for travel to otherstars andgalaxies.

Challenges

The greatest challenge of interstellar travel is the enormous distances between stars. Proxima Centauri, the nearest star to the Sun, is about 4.2light-years away, more...