Patent Number: 
Section: claims

1. A method, operable in the presence of an ambient flux of cosmic rays, of braking an asteroid upon approach to a lunar or planetary surface, comprising:projecting deuterium-containing particle fuel material in a specified direction outward from a landing site on a lunar or planetary surface toward an approaching asteroid, the asteroid having a mass of not more than 100 metric tons, the asteroid also provided with its own onboard propulsion system,dispersing the material as a cloud directly in an incoming flight path of the asteroid, the material interacting with the ambient flux of cosmic rays to generate products having kinetic energy; andreceiving by the asteroid of at least some portion of the generated kinetic-energy-containing products to produce thrust directed generally away from the lunar or planetary surface that decelerates the asteroid as it approaches the landing site at a specified trajectory. 2. The method as in claim 1, wherein the deuterium-containing particle fuel material is projected from a pre-positioned system at the landing site to a specified location outward from the asteroid such that the generated kinetic-energy-containing products pushing against the asteroid produce braking thrust according to a desired asteroid trajectory toward the landing site. 3. The method as in claim 2, wherein the pre-positioned landing site further includes radar tracking equipment for determining position, velocity, and trajectory of the asteroid as it approaches the landing site and directs the projecting of the fuel material to a calculated location in relation to the approaching asteroid. 4. The method as in claim 2, wherein the pre-positioned system also disperses a cloud of the deuterium-containing particle fuel material in the immediate vicinity of the landing site such that generated kinetic-energy-containing products create a braking cushion at the landing site. 5. The propulsion system as in claim 1, wherein the deuterium-containing particle fuel material comprises Li6D. 6. The propulsion system as in claim 1, wherein the deuterium-containing particle fuel material comprises D2O. 7. The propulsion system as in claim 1, wherein the deuterium-containing particle fuel material comprises D2. 8. The propulsion system as in claim 1, wherein the deuterium-containing particle fuel material is in solid powder form. 9. The propulsion system as in claim 1, wherein the deuterium-containing particle fuel material is in pellet form. 10. The propulsion system as in claim 1, wherein the deuterium-containing particle fuel material is in frozen form. 11. The propulsion system as in claim 1, wherein the deuterium-containing particle fuel material is in liquid droplet form. 12. The propulsion system as in claim 1, wherein the deuterium-containing particle fuel material also contain up to 20% by weight of added particles of fine sand or dust. 13. The propulsion system as in claim 1, wherein the deuterium-containing particle fuel material is projected outward from the landing site as successive packages. 14. The propulsion system as in claim 13, wherein each package is configured to disperse the deuterium-containing particle fuel material as localized cloud at a specified distance from the asteroid. 15. The propulsion system as in claim 1, wherein each landing site has at least one gun and a set of shell projectiles to be shot from the at least one gun to target areas for fuel material dispersal. 16. The propulsion system as in claim 15, wherein the shell projectiles contain a chemical explosive and a fuse configured to disperse the fuel material as a localized cloud at a specified distance from the asteroid. 17. The propulsion system as in claim 15 wherein each shell projectile comprises a shell wall encasing the fuel material with a fuse and chemical explosive charge activated by the fuse. 18. The propulsion system as in claim 17, wherein the shell projectile further comprises a cartridge case containing a propellant for projecting the shell to a targeted location. 19. The propulsion system as in claim 17, wherein the fuse comprises a timer for activating the explosive charge at a specified time after projection of the shell. 20. The propulsion system as in claim 17 wherein the fuse comprises a location detection system for activating the explosive charge when the shell reaches a targeted location.