Interstellar

Interstellar distances

Astronomical distances are often measured in the time it would take a beam of light to travel between two points. Light in a vacuum travels approximately 300,000 kilometres per second or 186,000 miles per second. (1μc = 670.6mph)

The distance from Earth to the Moon is 1.3 light-seconds. With current spacecraft propulsion technologies, a craft can cover the distance from the Earth to the Moon in around eight hours. That means light travels approximately thirty thousand times faster than current spacecraft propulsion technologies. The distance from Earth to other planets in the solar system ranges from three light-minutes to about four light-hours. Depending on the planet and its alignment to Earth, for a typical unmanned spacecraft these trips will take from a few months to a little over a decade.

The nearest known star to the Sun is Proxima Centauri, which is 4.23 light-years away. The fastest outward-bound spacecraft yet sent, Voyager 1, has covered 1/600th of a light-year in 30 years and is currently moving at 1/18,000th the speed of light. At this rate, a journey to Proxima Centauri would take 72,000 years. Of course, this mission was not specifically intended to travel fast to the stars, and current technology could do much better. The travel time could be reduced to a few millennia using lights sails, or to a century or less using nuclear pulse propulsion. A better understanding of the vastness of the interstellar distance to one of the closest stars to the sun, Alpha Centauri A (a sun-like star), can be obtained by scaling down the Earth-Sun distance (~150,000,000 km) to one meter. On this scale the distance to that star would be 271 kilometres or about 169 miles.

No current technology can propel a craft fast enough to reach other stars in under 50 years.

Nearest neighbouring stars, Alpha Centauri (which is viewable only from Earth's Southern Hemisphere) is a triple star system just over 4-light-years distant, Currently the closest star to our our own solar system Proxima Centauri Distance: 4.2 LY is the third star in the Alpha Centauri star system, also known as Alpha Centauri C.

Barnard's Star is next at 5.9 LY a faint red dwarf star, discovered in 1916 by E. E. Barnard Spectral Type: M3.8V

Project Daedalus

interstellar travel using current or near-future technology, British Interplanetary Society.

Project Daedalus had three goals. First, the spacecraft was to be designed using current or near-future technology. Second, the spacecraft must reach its destination within a working human lifetime and third, the spacecraft was to be be designed to allow for a variety of target stars. The final design solution was published in a special supplement of the Journal of the British Interplanetary Society in 1978. The two-stage engine configuration was powered by inertial confinement fusion using deuterium and helium-3 pellets. Electron beam diodes positioned around the base of the engine exhaust would impinge on the pellets and ignite them to produce large energy gain, at a rate of 250 detonations per second. This would continue for a boost phase lasting over 3.8 years, followed by a cruise phase lasting 46 years, travelling at over 12% of the speed of light until the 450-ton science probe would finally reach its destination, the Barnard’s Star system 5.9 light years away. This it would transit in a matter of days, for Daedalus was a flyby probe.

Interstellar Travel: Approaching Light Speed

Interstellar Migration and the Human Experience

by Ben R. Finney and Eric M. Jones (Berkeley: University of California Press, 1985). This volume is made up of the proceedings of the Conference on Interstellar Migration held at Los Alamos in May of 1983, an event attended by practitioners in a wide spectrum of sciences, from astrophysics to anthropology. Its insights into societal migration, emerging technologies and our evolving human future frame a debate that will engage us throughout this century and beyond.