Source: Lockheed Martin
quote: In fact, thats the main thing I think we lack between us and the original Enterprise or a Babylon 5 sort of Earth ship; energy so cheap as to be an afterthought. If it weren't so expensive to kick things in to orbit, then everything else for a ship that didn't care to leave the solar system is in place or close to in place.
quote: 4.24 light years / 100 years = 0.0424c = 12,711 km/sec.
quote: To put something into low earth orbit, you "only" need to reach about 8 km/sec. Energy goes as the square of velocity, so to get a spacecraft to the nearest star within 100 years, you'd need (12711/8)^2 = 2.5 million times as much energy as needed to put the craft into low earth orbit.