Project Orion
by George Dyson
2002, Henry Holt and Co
ISBN 0-8050-7284-5 (pbk)
Recently, George Dyson wrote a book on Project Orion, a project on
which his father, Freeman Dyson, worked in the late 1950s. The
project designed a heavy spaceship that could carry people to other
planets in a reasonably time. The spaceship would be driven by
exploding nuclear bombs behind it, one or two very second for 10 or 20
minutes. (As I say below, it occurs to me that the Chinese might want
to fund such a project now.)
The key technical understanding was that a steel plate, covered by a
thin coating of oil, could survive a nearby nuclear explosion. The
oil (which could be sprayed on) would ablate; the steel plate, while
accelerated violently, would survive.
The steel `pusher' plate would be coupled through two shock absorbing
systems to a multi-thousand ton human-carrying main body. The human
passengers would survive because the shock absorbing systems would
convert the high acceleration, short pulses of the exploding bombs
into a gentler, longer, 2 to 6 gravity, bearable acceleration. The
huge mass of the spaceship would provide shielding against the
radiation from the explosions, as well as against radiation from solar
flares and the like. The bigger the spaceship, the smoother the ride
and the thicker the shielding. Moreover, the bigger the spaceship,
the lower the incremental cost for bombs, since it is cheap to make
bombs bigger, once you have an initial hydrogen bomb.
According to calculations by Freeman Dyson, about 10 people over the
world would die from radiation poisoning from each launch. He made
this calculation at a time when the same calculations told him that
about 1000 people died each year from the then on-going atmospheric
nuclear tests. (Dyson was very disturbed by the amount of radiation
released in each launch; he hoped that bomb designers could design
`cleaner' bombs.)
No Orion spaceships were built. One reason is that the US Air Force,
who liked bombs, could not figure out a reason to explore the solar
system. NASA, on the other hand, did not like bombs. Then the test
ban treaty came along. While Orion might be considered `peaceful',
and thus permitted, few wanted to explode any atomic bombs in the
Earth's atmosphere.
I think that if the project had started two or three years earlier, so
that a vehicle had already been designed by the time Sputnik was
launched in the Fall of 1957, the US would have built and launched one
in the summer of 1958. This launch would have `proven' US prowness
over that of the Soviets, taken place while numerous atmosphere
nuclear tests were taking place, and taken place before ICBMs with
thermonuclear warheads became a primary US strategic weapon.
But, as I said, the project died. Nonetheless, it provides for great
`what if' parallel world questions.
As for the present: it occurs to me that the Chinese government might
want to undertake an Orion project. They could technically.
>From their point of view, the Chinese government might seek a fleet of
Orion spaceships carrying nuclear weapons. They would gain immediate
defensive strategic parity with the US. They could offer a promise of
retaliation to Japan and South Korea if any neighbor attacked.
Moreover, they could threaten to attack any US warship that came to
defend Taiwan against mainland threats, without risking too much that
the US would launch an all out nuclear attack.
The Chinese could do this by launching an Orion vehicle straight up,
not crossing the US, to orbit beyond the distance of the moon. This
would mean that a Chinese attack could not be undertaken quickly,
which would comfort the US. (The US might well consider an Orion
vehicle in low earth orbit as highly dangerous, since if permitted to
cross over the US, it could launch a nuclear attack with almost no
warning.)
A distant orbit would also mean that missiles attacking the Orion
vehicle would be visible for a long time. Either they could be
destroyed, or the Orion vehicle could simply turn its pusher plate
towards it, so when the attacker exploded, the Orion vehicle would
simply experience a shove as it did during launch. Contemporary laser
and particle beam weapons are too weak to have much effect on an Orion
vehicle.
The US would, of course, build and launch its own Orion vehicles, but
design and construction might take several years. In the meantime,
the Chinese government could aim for `re-unification' with Taiwan both
by intimidating Taiwan more strongly than now, and by offering more
benefits for accepting mainland colonization.
Possibly, mainland China could take over Taiwan. Certainly, the goal
is one that the Chinese government supports. The issue for it is risk
and cost. Is it worth bringing the `rebel' province to heel?
For the Chinese, an Orion project would provide it with a way to
intimidate Taiwan, a way to gain strategic parity with the US, and a
way to offer Chinese scientists, as well as scientists from other
countries, a way to explore the solar system.
The US would not want to launch many vehicles itself, because of the
radiation release. Only after the US succeeded with something such as
the `Z-pinch' implosion technique being developed in Los Alamos, would
it possess a relatively radiation-free trigger for its bombs.
(Of course, Freeman Dyson might be right in thinking that relatively
radiation-free bombs using plutonium, uranium, or other elements
could be designed and built. If that is the case, the US could launch
many Orion spaceships and the environmental questions would turn to
the ozone layer, how many people and animals are blinded at each
launch by the explosive flashes, and so on. Incidentally, Ted Taylor
hopes Dyson is wrong. Taylor ran the Orion project, and before that
designed both the largest and the smallest fission bombs the US
exploded. He worries that someone could design bombs that require
very little fissionable material, thus making proliferation much
cheaper.)
The main complication is getting replacement crews up to an Orion
spaceship after it has been launched. Few want to try to land an
Orion spaceship back on the earth (or splash it down in the ocean, a
more likely `landing' spot).
Nonetheless, crews must be replaced. Ordinary chemical rockets, for
all their expense, might do. Or thermal, nuclear rockets, such as
those tested in the 1960s, might be developed into working vehicles.
The US would probably use chemical rockets, at least initially. One
problem with nuclear thermal rockets is that they release fission
products into their exhaust.
As far as we know, the Chinese are working only on chemical rockets.
But if they did go for an Orion project, then it would make sense for
them to design and build nuclear thermal rockets as `shuttles' to
carry people from the surface of the earth to Orion vehicles, and not
to worry about the radiation release.
In 1958, the people in the Orion Project thought they would be
exploring the rings of Saturn by 1970. As George Dyson said, unlike
nuclear weapons, where the design process was more interesting than
the outcome, in the Orion project, the outcome would be more
interesting than the design process.
--
Robert J. Chassell Rattlesnake Enterprises
http://www.rattlesnake.com GnuPG Key ID: 004B4AC8
http://www.teak.cc [EMAIL PROTECTED]
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