Documents / Report
This Defense Intelligence Reference Document, dated 1 November 2010, was produced by the Defense Intelligence Agency under its Advanced Aerospace Weapon System Applications (AAWSA) Program. It surveys propulsion technologies that include chemical, ion, and nuclear fission rockets, fusion schemes, aneutronic fusion, and antimatter propulsion. It also covers radiation shielding and speculates on research needs over the next 30 years for missions from low Earth orbit to Mars, Jupiter, Saturn, and Alpha Centauri. The document concludes that aneutronic fusion promises to be an important mechanism for future space propulsion.
UNCLASSIFIED/ /F81il 8FFI1il.t.k Wfili &,.kY Specific Impulse To compare various propulsion systems and their fuel, rocket efficiency can be represented by the amount of momentum that can be obtained per unit weight of the propellant that is used. This is defined as the "specific impulse" (lsp) and is measured in units of seconds: 1" (m V ) V,.,,,,,,,,,e.dwii.11 , ~ (1.5) Here, earth's gravitational acceleration, gearth, is 9.81 m/s2 . As described earlier, the best propulsion system is typically one that has the highest possible exhaust or propellant velocity. High specific impulse, or correspondingly high exhaust velocity, also produces low energy efficiency. Table 1: Specific Impulse for Various Rocket Engine Types Enoine T~"'e Ve <m/sl Is~ <sl Saturn V Rocket 2nd and 3rd Staqes 4,130 421 LH2/LOX Liauid Fuel Solid Rocket 2,500 255 Best Chemical Rocket Tested 5,320 542 Fdli/H2 Chemical Rocket Nuclear Thermal Rocket 8 340 850 Ion Thruster 29 000 3 000 VASIMR 290 000 30 000 The efficiency of a rocket can be defined as the ratio of rocket thrust to the power required to generate the thrust. The resulting equations follow: Power= dE = ½(dmJ V' dt 2 dt ' Thrust = (:~JV,, 3 UNCLASSIFIED/ /1"9i.! 91"1"!e!llit tl:31! 911E I (1.6) (1.7)
Not linked to a story yet.
Report, from the dia collection. The PDF is mirrored here; the original link is above. 50 pages are in the text index: search them above, or from the library's search.