Image via WikipediaLofstrom loop (n.) - An enormous man-made magnetic track designed to launch payloads into orbit without the use of conventional rockets or propulsion systems. And by enormous, we mean puts-some-mountain-ranges-to-shame gigantic, with oft-cited estimates of a Loftsrom loop's necessary dimensions placed at 2000 kilometers long and 80 kilometers high. Some weather systems could pass cleanly underneath a Loftsrom loop. These structures are also known more simply as launch loops, but are often identified with electrical engineer Keith Lofstrom, who fleshed out the physics behind this pharaohic rocket-replacement system.
A Lofstrom loop works by magnetically rotating a belt along its entire length, sort of like a hybrid between the checkout line out the supermarket and a Japanese bullet train. The motion of the belt is what keeps the loop aloft in near-orbital space, since there's no way to build a self-supporting 80 km-high structure with known materials. Ironically, a Loftsrom loop is a simpler and cheaper alternative to the more popularly known space elevator, as the loop doesn't require placing any part of its structure in space, and doesn't (theoretically) require any knew materials for its construction -- just insane, science-fictional boatloads of money, and a constant 200 megawatt power source that never, ever stops. Oh, and you have to build it over the ocean because the loop's collective inertia rivals that of a small nuclear weapon's force output, so a cable break could theoretically wipe a small city off the map if you built it over a residential...er...continent.
I bring it up because: Today is the 40th anniversary of the launch of Apollo 11. On July 16, 1969, one of only 13 Saturn V rockets ever built hurled into space the first manned mission to the surface of the moon. It cost over $45 billion in today's money to design and build the fleet of Saturn Vs, and 40 years later, we still don't have any better vehicle than the massive controlled-explosion skyskrapers we call rockets to put payloads into space. Oh, and that "next generation" launch program called "Apollo on steroids" that will produce the Ares V rocket and the Orion/Altair vehicle fleet? Charles Stross rightly points out that the kind of NASA that could build that rocket is long gone, so the next great rocket will never be built. If we're going to get back into space in a serious, manned-expedition way, it's going to take a radical new technology, and maybe even a loopy one.