In October 2001, the “Voyage” 1 to 10-billion scale model of the Solar System was installed at the National Mall in Washington, DC. On this scale, the model Sun is the size of a large grapefruit, with a diameter of 13.9 cm. Starting at the Sun, you arrive at the model Earth (which is smaller than a pin head) after walking 15m westward. The furthest planet in our Solar System, Neptune, is about 600 metres away. Remarkably, to reach the closest star (Proxima Centauri) at the same scale, you would have to travel approximately 4000 km to a location on the Californian coast.

This vividly illustrates the vastness of interstellar distances, posing formidable technical and scientific hurdles that must be overcome to make star-to-star travel a reality.

This article concentrates on travel to systems within our local stellar neighbourhood, within a distance of 25 light-years. It examines sub-lightspeed propulsion concepts, potential hazards presented by the interstellar medium and how human beings could survive the protracted travel times involved.