If I tell you there was a plan to launch
a spacecraft the size of an ocean liner, that would weigh
130 times more than the Space Shuttle,
could travel at unrivaled speed across our solar
system, and was powered by riding on a series of
pulses, created by exploding thousands of
miniature atomic bombs, one after another
after another behind the ship, you'd probably
say that i've been reading far too many sci-fi
books and watching films.
However, in the 1950s and 60s, just
such an idea was taken very seriously.
Project Orion was a classified American project
to harness the power of the atom, to lift
extreme payloads, into Earth's orbit and beyond.
After the launch of Sputnik by the Soviet Union,
the shock to the US establishments was so great,
that almost any idea to catch up and overtake them, was
up for grabs.
The first calculations into nuclear pulse propulsions
appeared in the 1947 memo co-written
by the famous physicist Stanislaw Ulam,
who worked on early nuclear test at the Los
Alamos Laboratory. His idea was to detonate
a nuclear device in a combustion chamber, and inject
water as propellant. By 1955
the concept had developed, and in a report
co-authored by Ulam, set out a better model,
to propel a projectile by external detonation
of nuclear bombs.
The goverment research agency ARPA, the
Advanced Research Project Agency, gave a
million dollar contract to the General Atomic's
lab near San Diego, to develop the idea
into a working concept
General Atomic was set up after the Second World War
to explore the peaceful way to use
nuclear energy. The project was led by
physicist Ted Taylor with a team of scientist,
many who have worked on the hydrogen bomb, including
Stanislaw Ulam himself and the renown
British mathematician Freeman Dyson. Although
these physicists enjoyed playing around with bombs,
they also dreamed of using their discoveries
for constructive and humanitarian purposes.
Project Orion had obvious military uses,
but the team focused their vision for travelling to
the far reaches of the Solar System,
to transport a crew of hundreds of scientist
to explore Mars, Venus, and the moons
of the gas giants Saturn and Jupiter. The
concept was simple and based on technology which
were readily available to the US Military in the 1950s.
A series of small nuclear bombs, each the
equivalent of about 5 kilotons of TNT,
would be ejected from the back of the ship
at a rate of 2 to 4 per second.
These bombs would be made to direct most
of their energy toward the ship's 1000
tons steel pushing plate. And its these
series of pulses which would propel the huge spaceship
foward
To demonstrate the concept the team at General Atomic
built a 1 metre or 3 foot diameter model
shaped on a bullet, which would then loaded
with conventional explosive charges. Sure enough,
the model cruised up into the sky
riding on a chain of explosions
with suprising stability. According to the
calculations, the forces on the full-sized Orion
would be similar to around 2 to 4 G,
which is comparable to a conventional rocket launch.
Nuclear pulse rockets also offered some significant
advantages for spacecraft design. With
this kind of propulsion, it would not only be possible to
build heavy spacecrafts, it would actually become
an advantage to go big. The Orion
spacecraft would already need to be heavy, to absorb
the forces of the nuclear pulses through its pusher plates
and the giant shock absorbers. So rather than using lightweight composite
material like the Apollo spacecraft
the payload and living quarters of Orion
could be made from ordinary steel. In the words of a physicist Harris Mayer, "It would become
a project of standard engineering", like building
the Brooklyn Bridge. The Orion spacecraft
would be constructed in submarine shipyard
and would be similar in many ways to a nuclear submarines
already being built by General Atomic sister company
General Dynamic. Both had to be
able to support crew for an extended trip, and
withstand pressure. The vacuum in space
being less punishing than the compression of a deep sea
dive
Appropriately, the plan was to launch
the Orion spaceship at sea, just like
the concept of a sea dragon rocket, which was in development
at the same time.
Launching at sea removed
the need of huge launch pad and also
avoided issues with deflection of debris during the first moment after
launch. The sea launch of Orion would have been
a spectacular sight.
A succession of large explosions
each brighter than the Sun, lifting
the giant spaceship up vertically above
a series of fireball clouds. However,
the General Atomic's engineers faced unique and significant
challenges.
One of which, was of the shock of each explosion could not
be so large just to the injure human occupant or shaved the craft apart. Freeman Dyson's calculations
showed that it would take about 800 bombs
to lift the Orion spacecraft into low
Earth orbit.
And many more
for the interplanetary
travel thereafter
The effect of these bombs exploding in the atmosphere
would be a lot of nuclear fallout.
Unless a solution could be found to clean up the radioactive
debris, this was a major obstacle
in the way of Project Orion becoming a reality.
However, the high stakes of the Cold War
pushed the development of the project towards potential
military applications. Thomas Power
second in command of the Strategic Air Command reportedly said,
"Whoever controls Orion, will control the world".
However, when President Kennedy
was shown a model of a militarized
Orion, complete with nuclear missiles and atomic
cannons as a monstrous orbital battleship,
he was horrified.
To Kennedy, the last thing the world needed was a huge
nuclear weapons raised in space.
Orion had been touted as an alternative to the
Saturn rocket for the Moon missions,
but NASA was a civilian and open organization,
and Orion was still a top secret project
under control of the US Air Force.
In fact, many parts of the Orion project like
the construction of the
small, cheap atomic bombs, are still
highly classified, so as to keep the technology from
falling into the wrong hands.
Public mood was also shifting against the
emerging nuclear powered future. Strontium-90,
a byproduct of fission, had been
detected in the milk and in
baby's teeth
In the face of these health concerns and the global
panic of the Cuban Missile Crisis,
Kennedy signed the partial Nuclear
Test Ban Treaty in 1963. This
ruled out all above ground nuclear testing and
effectively made Project Orion
unworkable.
To the scientists who already spent 5 years working on
the project, the technology was too powerful to ignore.
After all, no other technology
offered the same potential for taking large payloads
to other planets.
In 1964,
NASA considered using a smaller
nuclear pulse rocket that could be launched aboard the Saturn V
and then assemble it in orbit. This would be
8 man crew to go to Mars or 20 man crew
to go to Jupiter. However, by this time the Space Race
was fully focused on the Moon landings and
the job didn't need a rocket anywhere
as powerful as Orion. Finally, in 1964
the project was terminated.
Chemical rockets, inefficient but relatively safe
would be the only way of getting off the Earth.
Since Project Orion, the principles of nuclear
pulse propulsion have been revisited many times.
In 1968 Freeman Dyson wrote
a paper entitled "Interstellar Transport", in
which he calculated that a version of the Orion ship
could travel to Alpha Centauri, our nearest
star at 10% of the speed of light, taking 44
years to arrive.
Five years after Dyson's paper, the British
Interplanetary Society conducted a study
into a potential mission using a nuclear pulse
propulsion system. Known as Project Daedalus,
the concept envisioned building a 190 metre
or 620 foot long robotic spacecraft
in Earth's orbit, which would then travel to Jupiter
to scoop up 50 thousand tons of Helium-3
from the gas giant's atmosphere. The fueled
Daedalus would then accelerate out of the Solar System
reaching 12% of the speed of light on a 50
year voyage to Banard's star. However,
unlike Project Orion, Daedalus relied upon
nuclear fusion, a technology that is still
out of reach.
According to George Dyson, son of Freeman Dyson,
a team at NASA have a contingency plan to put
nuclear pulse technology into action if
a large asteroid is discovered on a collision
course with Earth.
In such a situation, a version of Project
Orion might be our only chance
to deflect the asteroid earlier and with greater velocity
than we could with conventional spacecraft.
With the cancellation of NASA's Asteroid
Redirect Mission in President Trump's budget,
a version of Project Orion could still
appear if the need arose
at some future point to change
the course of human history.
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