AAWSAP DIRD, Aneutronic Fusion Propulsion I, November 2010
DOW-UAP-D145 · page 34 of 50
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UNCLASSIFIED//POR. Offl@IAI:: ~S& Qptk\f • Antimatter drives: - Antimatter/fission. - Antimatter, propellant and Laval nozzle. - Antimatter, electrical generation, ion drive. - Antimatter, electrical generation, photon drive (Sanger). • Speculative technologies: - Heim graviphoton drive. - Black hole energy source. To look at the role of fusion propulsion over the next 30 years and beyond, we can envision four kinds of missions: surface to LEO (low-Earth orbit); LEO to Mars; LEO to Saturn; and LEO to Alpha Centauri A, B, or C. While technical hurdles will certainly be at the forefront for each mission, safety factors and fuel concerns will also contribute to the optimal propulsion technology chosen . SURFACE TO LOW-EARTH ORBIT ( 100 MILES) The energy required to move one kilogram of mass into LEO 100 miles above the surface of the Earth is about 30 MJ (8.5 kW-hr). The energy required to move this same mass from LEO to lunar orbit significantly smaller, yet the transit time can be very long. Chemical rockets, such as the Saturn V, have successfully launched satellites and the Apollo missions into earth orbit using RP-1 and LOX (liquid oxygen), along with LH2 (liquid hydrogen) in the second and third stages). Proximity to the Earth's surface requires propulsion systems that are safe to the population and to the environment. The Rover Project in the 1950s explored the use of nuclear fission NERVA (Nuclear Engine for Rocket Vehicle Application) rockets, but ejection of radioactive debris made these rockets untenable for use on Earth. Fusion and antimatter systems suffer the same problem. Chemical rockets will continue to move humans into local space until another technology is available. Given sufficient technical and financial support, additional systems may be explored over the next 30 years: • The Space Tether: This involves a carbon nanotube tether that connects a spaceport on the Earth's surface to a station in geosychronous orbit above the equator. Carbon nanotubes are extremely strong, yet fibers of sufficient length to fabricate into a tether are not yet available. This is an active area of research (http://www.spaceelevator.com) with scientific progress presented at regular conferences. Cargo and passengers would be moved into LEO using an elevator attached to the tether. • SSTO (Single Stage to Orbit): Multistage rockets are now used to attain Earth orbit since most of the energy expended by the rocket is used to lift the rocket and its fuel. The space shuttle is based on an earlier design by Eugen Sanger in 1930s UNCLASSIFIED/fF&A &FFI€il.t.k W&& Qptk\f 26