Magnets and Space Travel
Future scenario: A 20,000 pound scramjet powered, unmanned launch vehicle sits waiting on a glittering five-mile long track. At T minus 2 seconds, six solid rocket engines ignite on sled to which the winged aircraft is attached. At T zero, the sled begins to accelerate down the permanent magnet-embedded track, reaching sub-sonic speeds in under 10 seconds.
At T plus 6 seconds, the scram jet engine ignites, as aerodynamic forces over the craft's wings begin to exert lifting forces. At T plus 9.5 seconds, the mechanical shackles holding the launch vehicle to its sled, release and moments latter, as the aircraft lifts off its track, the rocket motors on the sled shut down, as it gradually coasts to a stop another two miles down the track, but not before the desert air reverberates to the crack of a sonic boom, as the scramjet vehicle goes supersonic and arches high into the gathering dawn, a thin vapor trail marking its ascent to the edge of space where its payload will be deployed at a fraction of the current cost of chemical rocket launches. Its mission complete, ground controllers bring the launch vehicle back down to earth to be refitted for its next mission two weeks later.
NASA and other researchers have been investigating this scenario for years now. They've built a working scale model track at the Marshall Space Flight Center in Huntsville, Alabama (see above photo), but beyond that there's not been much progress. The reason has largely to do with cost. The dreams of magnetic launchers and maglev trains have been stymied by the complexity of the technology and its cost, says John Barber, a retired NASA engineer who thinks he may have a way to get around these problems using permanent magnets instead of linear motors, the current favored solution.
In what Barber calls one of those 3 AM "Aha!" moments, he hit upon his solution and eventually patented it: not to launch space vehicles or run high speed trains, but to move heavy sliding doors with almost no effort by way of magnet levitation. Now living in Spokane, Washington, John runs Modern Transport Systems Corp., a start-up, that has developed the "Magneglide" Sliding Door Magnetic Support System based on the properties of like magnetic poles repulsing each other and opposite poles attracting one another. Below are two of the key components of his track system that are based on permanent magnets. At the bottom of the page is an early computer rendering of a permanent magnet-based track system he's developed, along with its rocket-propelled sled and launch vehicle.
While the linear motor approach being explored at MSFC eliminates the need for Barber's rocket sled, relying entirely on electrical power, the beauty of his system is its simplicity, and the fact that, at the moment, the price of permanent magnets are very cheap comparatively, that is as long as China continues to export them and has enough rare earth elements to fabricate them. [Would you bet who'll have an operating magnetic launch system in operation first?]
To listen to this 33-minute interview, use either of the two MP3 players to the right, or download the 7.11MB file to your computer for transfer to and playback on your favorite MP3 device.
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