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Some Novel Space Propulsion Systems

Forrest Bishop*

Institute of Atomic Scale Engineering

This is an abstract for a poster to be presented at the Fifth Foresight Conference on Molecular Nanotechnology.

The rapidly improving ability to build atomically precise structural materials of extreme strength-to-mass ratio will permit a revolution in aerospace engineering. Graphenes, or 'Buckytubes' may become available in commercial quantities, allowing the realization of previously untenable proposals, such as the 'Skyhook', or geosynchronous tether, for example. A number of novel spacecraft propulsion systems and machines are presented, as well as new applications for some very ancient devices. The crossbow and other mechanical catapults are re-examined in light of this materials development. A design for an electrically powered and braked, fully automatic Graphene crossbow capable of loosing 10 kg payloads at several km/sec is presented.

A Solar System-wide transportation system is proposed by the author for freight and for spacecraft propulsion. A network of accelerator/decelerator stations in various positions around the Solar System pass 'Smart Pellets' and other forms of matter and energy between each other, to planets and other bodies, and to spacecraft in transit. The systems presented here are amenable to inclusion in that proposal.

Between the proposals for particle beam and pellet stream spacecraft propulsion lies an immense, largely unexplored spaceflight regime. Pushing a spacecraft using a collimated beam of mesoscopic particles, very roughly on the order of a nanogram mass each (plus or minus several orders of magnitude), presents new opportunities for high speed interplanetary manned transportation. This kind of beam can be tailored in velocity, mass flow, and beam profile parameters to fit the mission requirements. The receiver onboard the spacecraft may be as simple as a pusher plate, or may incorporate particle ionization and magnetic mirroring.

The ballistic coefficient, or mass-to-cross-section ratio of this type of particle is much greater than single atom particle beams, allowing more precise control over pointing and dispersion. With atom counts per particle reaching into the millions, molecular nanotechnologies may permit the inclusion of entire guidance systems.

The performance of the rotating tether, or sling, is considerably enhanced by constructing it of Graphene fiber. A relatively short sling with a reasonable taper ratio can attain tip velocities of several tens of km/sec, along with firing rates of several hertz, making it an attractive substitute for the Mass Driver. Scaling down further, the notion of a mesoparticle sling is introduced. A planar array composed of many thousands of centimeter-size slings and associated support systems forms a type of mesoparticle beam projector.

Combining the concepts of solar sailing and mesoparticles leads to the notion of mesoscopic solar sails. A mesoparticle beam composed of thin film sails with nanoscale electronics and actuators may be able to accelerate, turn, and navigate itself to a target spacecraft. Its accelerator may be the Sun, or a laser located on a deep space 'relay station'. Several sail structures are presented. The magnetic sail analog, though suffering a scaling disadvantage, is also investigated.

*Corresponding Address:
P. O. Box 30121, Seattle, WA 98103, ph: (206)-367-5268, email: (abstract references available)
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