dietz@SLB-DOLL.CSNET (Paul Dietz) (01/06/86)
Here's an extension of the dust accelerator idea I proposed several months back (I learned recently that the idea of using electrostatically accelerated dust as reaction mass is an old one; Arthur Clark used in his novel "Earthlight"). The new idea is to use such an electrostatic accelerator to lift mass off the moon. This scheme as some attractive features: (1) no superconducting buckets are needed, so nothing needs be recirculated, (2) very much smaller payloads may be accelerated, allowing the catcher to be miniaturized, and (3) peak power in the electrical supply may be lower. I envision accelerating positively charged microgram to milligram sized particles in a linear accelerator driven at several kilohertz. The particles would be neutralized after acceleration with a low energy electron beam. It is likely that the velocity dispersion of the dust particles will be much higher than that of a mass driver. However, because the particles are so small, we can afford to position a large number of small dust catchers in lunar orbit. The catchers would be sticky disks or spheres several meters across, placed in a low orbit passing over the accelerator site. As the catchers go downrange of the accelerator the dust beam would be directed against them for several minutes. This will eventually propel the catchers into higher orbits, where they can be cleaned and recycled. The transit time from accelerator to catcher will be a few minutes, so we can tolerate velocity dispersions of up to a few centimeters per second.