Quicklauncher is a space-cannon proposed by Lawrence Livermore National Laboratory physicist John Hunter. This 3,600-foot gun could make deliveries to an orbiting space station for just $250 per pound - compared to $5,000 per pound costs for delivery by rocket.
Hunter wants to operate the gun, the “Quicklauncher,” in the ocean near the equator, where the Earth’s fast rotation will help slingshot objects into space. A floating cannon—dipping 1,600 feet below sea level and steadied by a ballast system—would let operators swivel it for different orbits.
Next month, Hunter will test a functional, 10-foot prototype in a water tank. He says a full-size launcher could be ready in seven years, provided the company can round up the $500 million. Despite the upfront cost, Hunter says he has drawn interest from investors because his reusable gun saves so much cash in the long haul.
Just don’t ever expect a ride in the thing: The gun produces 5,000 Gs, so it’s only for fuel tanks and ruggedized satellites. “A person shot out of it would probably get compressed to half their size,” Hunter says. “It’d be over real quick.”
In theory, it works like this: First, the gun combusts natural gas in a heat exchanger within a chamber of hydrogen gas. Operators open the valve, and the hot hydrogen expands down the tube, boosting the payload, which exits the mouth of the gun at 13.000 mph.
Here's a complete talk presented at Google in December, 2009 by John Hunter.
(John Hunter presents Quicklauncher space-cannon)
Jules Verne famously elaborates on the idea of a space-cannon in his excellent 1867 novel From the Earth to the Moon; here's the proposal for the Columbiad:
"You know," said he, "what progress artillery science has made during the last few years, and what a degree of perfection firearms of every kind have reached. Moreover, you are well aware that, in general terms, the resisting power of cannon and the expansive force of gunpowder are practically unlimited.
Well! starting from this principle, I ask myself whether, supposing sufficient apparatus could be obtained constructed upon the conditions of ascertained resistance, it might not be possible to project a shot up to the moon?
...I have looked at the question in all its bearings, I have resolutely attacked it, and by incontrovertible calculations I find that a projectile endowed with an initial velocity of 12,000 yards per second, and aimed at the moon, must necessarily reach it. I have the honor, my brave colleagues, to propose a trial of this little experiment."