AAWSAP DIRD, Aneutronic Fusion Propulsion I, November 2010

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doubled that of typical chemical rocket designs. The largest NERVA rocket tested
generated 867 kN of thrust using liquid hydrogen propellant. NERVA rockets were
proposed for the Manned Mars Mission using a tethered cabin to protect the crew from
reactor radiation. The NERVA project was cancelled in 1972.
LEO TO THE MOONS OF JUPITER AND SATURN (460 TO 940 MILLION
MILES)
Project Prometheus, 2003-2005, concentrated on nuclear electric and nuclear thermal
propulsion for unmanned missions to the moons of Jupiter. For manned flight, the
nuclear thermal systems based on NERVA still provide high thrust, reasonable values of
specific impulse, and a technology that requires no major breakthroughs in order to be
achieved. For manned flights, tethered systems will likely be necessary to minimize
radiation exposure to the crew from the reactor. For the next 30 years, nuclear
thermal propulsion can be used to explore locations throughout the solar system based
on new engineered designs with no unresolved scientific hurdles.
Fusion reactors or fusion propulsion can be developed for missions throughout the solar
system, but there are many unresolved issues in their use. The fusion propulsion
technology that may show promise in the far-term are pulsed propulsion systems.
These concept designs include large sails or collectors that absorb the energy from
thermonuclear explosions initiated at a specific distance from the collector. Each
explosion generates a pulse that accelerates the vehicle forward. Design challenges
include protection of the crew from the radiation of the nuclear blast, cushioning the
crew from the incredible "jerk" or change in acceleration that occurs during each blast,
and the design of a suitable collector.
LEO TO ALPHA CENTAUR! (4.22 LIGHT-YEARS OR 24.8 TRILLION
MILES)
Alpha Centauri contains three of the closest stars to our solar system. Alpha Centauri A
and B are binary stars orbiting one another, yet each one is approximately the same
size as the Sun. Alpha Centauri C, or Proxima Centauri, is the closest at 4.22 light­
years and is a red dwarf. There is a limited possibility that Alpha Centauri has Earth­
like planets.
Rockets optimal for flights to these stars and destinations of similar distance would
require high specific impulse propulsion. Depending on other mission requirements, the
thrust may be kept low since the application of a small, but continuous thrust over a
long period of time leads to high velocities. Since aerobraking may not be possible, the
spacecraft can accelerate for half the trip and must decelerate for the second half.
Spacecraft acceleration can be low, and most designs for human flight focus on a
continuous acceleration of 1 g (Earth gravity) to provide optimal crew conditions.
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