Forget about warp drives and wormholes, the Daedalus class of interstellar spacecraft could make it to a nearby star in our lifetimes, and it’s doable with near-term technology. Also, it’s huge. (Pics and video)
Project Daedalus was originally conceived back in 1970s by the British Interplanetary Society, who figured that we might as well at least start designing an interstellar spacecraft, even if we (as a species) weren’t quite ready to build one yet. After five years and about 100,000 hours of work, they came up with Daedalus, an unmanned spaceship capable of getting to Bernard’s Star, six light-years from here, in under 50 years.
Daedalus, if it ever gets built, will be powered by a pulsed fusion engine. Pellets of deuterium mixed with helium-3 will be ignited by a ring of electron lasers and fired out the back of the engine, where a series of magnetic field coils will create a magnetic nozzle to focus the thrust. The primary boost phase would last two years, and then most of the craft would be jettisoned, and secondary stage would fire for an additional two years. At this point, Daedalus would be traveling at about 12% of the speed of light, and would go into cruise mode for 46 years before flying past Bernard’s Star in the space of just a few hours since it won’t be able to slow down.
This travel technique sucks down a lot of fuel, and as you can see, Daedalus would be pretty freakin’ big, utilizing spherical tanks to store propellant kinda like the antimatter pods on the Enterprise, except several orders of magnitude bigger. The 50,000 tons or so of fuel pellets in these tanks would use more helium-3 than could be comfortably produced on Earth, so 20 years before launch, a flotilla of robotic hot air balloons would be sent to Jupiter to harvest helium-3 from its atmosphere.
While the Daedalus Project sounds a little bit futuristic, it doesn’t require any major new physics breakthroughs to make it happen. It’s all more or less achievable using science that we’re currently familiar with. Currently, Daedalus has been resurrected in the form of Project Icarus, which aims to take the basic design of Daedalus and retrofit it to reflect 30 years of technological progress.