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
