STARSHIPS i6i
In outer space, however, the most abundant form of hydrogen consists
of a single proton surrounded by an electron. The ramjet fusion engine
would therefore have to exploit the proton-proton fusion reaction. Although the deuterium/tritium fusion process has been studied for
decades by physicists, the proton-proton fusion process is less well understood, is more difficult to achieve, and yields far less power. So mastering the more difficult proton-proton reaction will be a technical
challenge in the coming decades. (Some engineers, in addition, have
questioned whether the ramjet engine could overcome drag effects as
it approaches the speed of light.)
Until the physics and economics of proton-proton fusion are
worked out, it is difficult to make accurate estimates as to the ramjet's
feasibility. But this design is on the short list of possible candidates for
any mission contemplated to the stars.
NUCLEAR ELECTRIC ROCKET
In 1956 the U.S. Atomic Energy Commission (AEC) began to look at
nuclear rockets seriously under Project Rover. In theory, a nuclear fission reactor would be used to heat up gases like hydrogen to extreme
temperatures, and then these gases would be ejected out one end of the
rocket, creating thrust.
Because of the danger of an explosion in the Earth's atmosphere
involving toxic nuclear fuel, early versions of nuclear rocket engines
were placed horizontally on railroad tracks, where the performance of
the rocket could be carefully monitored. The first nuclear rocket engine to be tested under Project Rover was the Kiwi 1 in 1959 (aptly
named after the Australian flightless bird). In the 1960s NASA joined
with the AEC to create the Nuclear Engine for Rocket Vehicle Applications (NERVA), which was the first nuclear rocket to be tested vertically, rather than horizontally. In 1968 this nuclear rocket was
test-fired in a downward position.
The results of this research have been mixed. The rockets were
very complicated and often misfired. The intense vibrations of the nu-
In outer space, however, the most abundant form of hydrogen consists
of a single proton surrounded by an electron. The ramjet fusion engine
would therefore have to exploit the proton-proton fusion reaction. Although the deuterium/tritium fusion process has been studied for
decades by physicists, the proton-proton fusion process is less well understood, is more difficult to achieve, and yields far less power. So mastering the more difficult proton-proton reaction will be a technical
challenge in the coming decades. (Some engineers, in addition, have
questioned whether the ramjet engine could overcome drag effects as
it approaches the speed of light.)
Until the physics and economics of proton-proton fusion are
worked out, it is difficult to make accurate estimates as to the ramjet's
feasibility. But this design is on the short list of possible candidates for
any mission contemplated to the stars.
NUCLEAR ELECTRIC ROCKET
In 1956 the U.S. Atomic Energy Commission (AEC) began to look at
nuclear rockets seriously under Project Rover. In theory, a nuclear fission reactor would be used to heat up gases like hydrogen to extreme
temperatures, and then these gases would be ejected out one end of the
rocket, creating thrust.
Because of the danger of an explosion in the Earth's atmosphere
involving toxic nuclear fuel, early versions of nuclear rocket engines
were placed horizontally on railroad tracks, where the performance of
the rocket could be carefully monitored. The first nuclear rocket engine to be tested under Project Rover was the Kiwi 1 in 1959 (aptly
named after the Australian flightless bird). In the 1960s NASA joined
with the AEC to create the Nuclear Engine for Rocket Vehicle Applications (NERVA), which was the first nuclear rocket to be tested vertically, rather than horizontally. In 1968 this nuclear rocket was
test-fired in a downward position.
The results of this research have been mixed. The rockets were
very complicated and often misfired. The intense vibrations of the nu-