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PHVS1CS OF THE IMPOSSIBLE
he realized that the physics behind mini-nuclear bombs could also be
used by terrorists to create portable nuclear bombs. Although the project was canceled because it was deemed too dangerous, its namesake
lives on in the Orion spacecraft, which NASA has chosen to replace the
Space Shuttle in 2010.)
The concept of a nuclear-fired rocket was briefly resurrected by the
British Interplanetary Society from 1973 to 1978, with Project Daedalus, a
preliminary study to see if an unmanned starship could be built that
could reach the Barnard's Star, 5.9 light-years from Earth. (Barnard's
Star was chosen because it was conjectured that it might have a planet
Since then astronomers Jill Tarter and Margaret Turnbull have compiled
a list of 17,129 nearby stars that could have planets supporting life. The
most promising candidate is Epsilon Indi A, 11.8 light-years away.)
The rocket ship planned for Project Daedalus was so huge that it
would have had to be constructed in outer space. It would weigh 54,000
tons, nearly all of its weight in rocket fuel, and could attain 7.1 percent
of the speed of light with a payload of 450 tons. Unlike Project Orion,
which used tiny fission bombs, Project Daedalus would use minihydrogen bombs with a deuterium/helium-3 mixture ignited by electron beams. Because of the formidable technical problems facing it, as
well as concerns over its nuclear propulsion system, Project Daedalus
was also shelved indefinitely.
SPECIFIC IMPULSE AND ENGINE EFFICIENCY
Engineers sometimes speak of "specific impulse," which enables us to
rank the efficiency of various engine designs. "Specific impulse" is defined as the change in momentum per unit mass of propellant Hence
the more efficient the engine, the less fuel is necessary to boost a
rocket into space. Momentum, in turn, is the product of the force acting over a period of time. Chemical rockets, although they have very
large thrust, operate for only a few minutes, and hence have a very low
specific impulse. Ion engines, because they can operate for years, can
have high specific impulse with very low thrust.
PHVS1CS OF THE IMPOSSIBLE
he realized that the physics behind mini-nuclear bombs could also be
used by terrorists to create portable nuclear bombs. Although the project was canceled because it was deemed too dangerous, its namesake
lives on in the Orion spacecraft, which NASA has chosen to replace the
Space Shuttle in 2010.)
The concept of a nuclear-fired rocket was briefly resurrected by the
British Interplanetary Society from 1973 to 1978, with Project Daedalus, a
preliminary study to see if an unmanned starship could be built that
could reach the Barnard's Star, 5.9 light-years from Earth. (Barnard's
Star was chosen because it was conjectured that it might have a planet
Since then astronomers Jill Tarter and Margaret Turnbull have compiled
a list of 17,129 nearby stars that could have planets supporting life. The
most promising candidate is Epsilon Indi A, 11.8 light-years away.)
The rocket ship planned for Project Daedalus was so huge that it
would have had to be constructed in outer space. It would weigh 54,000
tons, nearly all of its weight in rocket fuel, and could attain 7.1 percent
of the speed of light with a payload of 450 tons. Unlike Project Orion,
which used tiny fission bombs, Project Daedalus would use minihydrogen bombs with a deuterium/helium-3 mixture ignited by electron beams. Because of the formidable technical problems facing it, as
well as concerns over its nuclear propulsion system, Project Daedalus
was also shelved indefinitely.
SPECIFIC IMPULSE AND ENGINE EFFICIENCY
Engineers sometimes speak of "specific impulse," which enables us to
rank the efficiency of various engine designs. "Specific impulse" is defined as the change in momentum per unit mass of propellant Hence
the more efficient the engine, the less fuel is necessary to boost a
rocket into space. Momentum, in turn, is the product of the force acting over a period of time. Chemical rockets, although they have very
large thrust, operate for only a few minutes, and hence have a very low
specific impulse. Ion engines, because they can operate for years, can
have high specific impulse with very low thrust.