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March 12, 2012

Crowlspace links to several older NASA studies on Nuclear Fusion for Space Missions

1. Fusion Energy for Space Missions in the 21st Century (496 pages, 25 megabytes. Note - George Miley was a big contributor to this 1991 document. (H/T Crowlspace).

Future space missions were hypothesized and analyzed and the energy source for their accomplishment investigated. The missions included manned Mars,
scientific outposts to and robotic sample return missions from the outer planets
and asteroids, as well as fly-by and rendezvous missions with the Oort Cloud
and the nearest star, Alpha Centauri, and even beyond. Space system
parametric requirements and operational features were established. The
energy means for accomplishing missions where A v requirements range from
90 km/sec to 30,000 km/sec (High Energy Space Mission) were investigated.

Massive amount of information on all the fusion options, as of 1991, including the Field Reversed Configuration, which is a favourite approach of Rostoker and co. Schulze computes the performance of different fusion rocket concepts, though the performance figures are surprisingly low. An Isp of 270,000 seconds for a probe to Alpha Centauri, which means multi-century mission times. Dyson’s “Orion” and “Daedalus” got 1,000,000-1,5000,000 seconds, though the designs aren’t as elaborated as Schulze’s.





2. 17 page presentation from 2004 on Helium-3 Mining Aerostats in the Atmospheres of the Outer Planets

Imagine an interplanetary future where: a) d-He3 fusion produces most of Earth s energy needs without radioactivity or carbon emissions; b) Space transportation has been revolutionized by an efficient fusion propulsion system with exhaust velocity up to 0.088 c; c) Space commerce is stimulated by the existence of an interplanetary cargo worth $3-M a kilogram; and d) Unmanned probes travel to the nearest star systems with flight times less than a human lifetime.

3. The Centauri project: Manned interstellar travel (13 pages from 1990)

The development of antimatter engines for spacecraft propulsion will allow man to expand to the nearest stellar neighbors such as the Alpha Centuri system. Compared to chemically powered rockets like the Apollo mission class which would take 50,000 years to reach the Centauri system, antimatter propulsion would reduce one way trip time to 30 years or less. The challenges encountered by manned interstellar travel are formidable. The spacecraft must be a combination of sublight speed transportation system and a traveling microplanet serving an expanding population. As the population expands from the initial 100 people to approximately 300, the terraformed asteroid, enclosed by a man-made shell will allow for expansion over its surface in the fashion of a small terrestrial town. All aspects of human life - birth; death; physical, emotional, and educational needs; and government and law must be met by the structure, systems, and institutions on-board.

4. Crowlspace looked at some other documents that examined fusion power for interstellar probes

Freeman Dyson, based on his work on “Project Orion”, led him to sketch a high performance interstellar version of “Orion” with a wholly different relationship to reaction heat. Instead of absorbing and re-radiating the heat, blow it away with the propellant in a massive thrust, with a very short heating period. Interstellar “Orion” used pure deuterium fusion devices with very high burn-up fractions (“burn-up” is the fraction of fusion fuel that actually fuses) which allowed high-performance. Dyson argued, for reasons of energy efficiency, that the mission velocity be kept to a low multiple of the effective exhaust velocity – his fusion devices had an exhaust velocity of 15,000 km/s (0.05c) and his “Orion” had a mass-ratio of just 4, meaning a total delta-vee of ~20,000 km/s. This meant trips to Alpha Centauri lasting ~130 years. A slightly higher mass-ratio would drop that to just 100 years – “Project Icarus” time-frames.

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