Article available on disk gdnordley@aol.com
In the year 2099, Nordley envisions a vast solar array 1000 km. wide and a quarter of a million kilometers long at least at the Sun-Venus L5 point to power a mass beam projector which is basically a giant particle accelerator or an actual mass driver to propel nanobot pellets. As Nordley says, "Such "Mass beams" may consist of streams of atoms, molecules, clusters, or pellets; anything that has rest mass and can be reflected (no neutrino beams, please!)." He envisons a starship consisting of "three long, parallel, teardrop shaped hulls...evenly spaced around a rotating, hundred-meter radius solenoid ring." The crew resides within a sperical inner hull of one of the teardrop shaped hulls and the whole thing rotates to generate centrifugal force. Don't expect electrical gravitational field generators in the future to create something like the Jupiter 2 or the starship Enterprise. Even starships of the real future will use centrifuges to generate artificial gravity. This design is most wise. It allows the inner spherical hulls to rotate into the direction of travel to allow acceleration to subsitute for gravity and then when cruise speed is reached they rotate back into the centrifugal pattern. As you may or may not realize, rotation stops during acceleration and resumes during cruise. During acceleration, Nordley's crew float in a pool in the center of the common room. They feel a slight unease as the "spherical inner hull turns to adjust to the new combination of centrifugal and lateral acceleration." Aboard my New York sized Star Carriers that were inspired by Nordley's ship and Clarke's alien Rama vessels, everybody just stays in their cabin during this transition and sleeps. It only takes a few days and is no worse than high seas in a luxury liner. Nordley's starship accelerates at five gravities. I leave my Carriers at one gee which means they will travel more distance from the Sun before reaching cruise speed and this will bring about beam dipersal problems. I can only imagine magnetic sails big enough to capture highly dispersed beams at great distances, but read on.
According to Nordley, mass beams for space propulsion were first described by H.O.Ruppe in the JBIS in 1948. In 1980, C.E. Singer wrote about them in the JBIS. In the late 1980s Zubrin and Andrews wrote about magnetic sails in the JBIS and Analog. Lots of papers were written later about the use of mass beams and magnetic sails.
One problem with particle beams is that charged particles will have a tendency to repel each other and spread the beam. Neutral particles might be the way to over come this or microscopic pellets might be used. Lasers in deep space could corral the particles and focus the beam. Particles that disperse from the beam or collide with interstellar dust grains will just have to be made up for by adding extra particles to the beam to make up for the losses. Nothing is 100% efficient. Fortunately, the magnetic nozzle or sail will have efficiency similar to that of an electric motor, say 90%-95%. To read Nordley's article, just email him at the address above. I recommend it.
