Page 164 - MY STORY

The NERVA engine used the nuclear reactor core as a heat

exchanger to heat liquid hydrogen to temperatures not
achievable with existing hydrogen/oxygen combustion
systems for thrust. The doubling of propulsion capability

using liquid hydrogen as the propellant fuel permitted
higher speeds to Mars with a reduction of travel time
from 8 - 9 months to as short as 2 – 4 months. Same

advantage coming home. By the 70’s enough testing had
been accomplished to prove the efficacy of
nuclear-powered systems.

Engines had been cycled on and off multiple times, the

propulsion efficiency was indeed doubled (actually
somewhat better), and burns lasting well over one hour
were accomplished with little or no degradation to the
pumps, hot components, and nuclear reactor. The nuclear

engine was to be used only from earth orbit to and from
Mars. Earth launches would use conventional propulsion

to put the “pieces” into low earth orbit.

Work had not commenced on propellant tank design, but

that was one of our great strength at McDonnell Douglas,
and some of our R&D was devoted to learning to
fabricate large, very thin wall tankage from high strength

titanium alloy.