His first TV scripts in LA reflected this line of work; he
wrote for TV shows called The Lieutenant, Have Gun - Will Travel, and Highway
Patrol. So where did all that sciencey technology come from?
Roddenberry was definitely a futurist. This series of posts
has shown, if nothing else, just how savvy he was in creating fictional
technologies that had an uncanny ability to become science realities. But, for
the life of me, where did he come up with gravitons – subatomic particles that
assign gravity to matter? He was walking a beat in LA in the 1960's. That sounds like
a lot more than just a convenient story-telling convention.
Gravitons played a role in several of the Star Trek
technologies, including today’s topic - deflector shields, or just “shields.”
There are a couple of different explanations as to how the shields on the USS
Enterprise worked, but the earlier and more accepted explanation in the Star
Trek cannon is that the ship had emitters that sent out graviton fields.
The idea of an electromagnetic shield is much closer to our
reality at present, since we haven’t yet identified a graviton particle. Electromagnetism
was a great choice for Roddenberry, since we all have experience with magnetic
fields (two similar poles on magnets will repel each other). Electrical fields
likewise repel similar charges. This sounds like a force field we could believe
in for the defense of a ship.
Humans on Earth in 2015 don’t have a real need for shields
geared to interstellar battle – we haven’t blundered into space wars yet. But
we do have a very pressing need for deflector shields in space. And we’re
coming close to achieving them.
NASA, the ESA, and many other space programs are taking aim
at Mars. We have sent probes, rovers, and satellites; now it’s time for humans
to make the trip. But this brings big problems along with the big promise. Space
is full of cosmic rays, high-energy electrons, high-speed protons and even heavier
atoms. They can all kill you over time or fry your equipment.
Radiation in space will make you sick at the least, and
don’t underestimate the problem of being sick in space – think about vomiting
in a space suit. But it can also damage DNA and most certainly lead to
infertility, given enough time and exposure.
All this damage could occur inside the space ship on a long journey
to Mars or beyond, not just on space walks. Most high-energy radiation will pass
through the hull of a spacecraft and do damage to the occupants. We need
protective shields to keep out the bad particles and waves.
We don’t have a chromodynamic shield, so we've been
looking to more conventional mechanisms of shielding. We could always make the
walls of a long distance spacecraft thicker. Concrete would work pretty
well, if it was dense and about 2 ft thick. A foot or so of aluminum might do
just as well. But these are very heavy. Heavy things don’t make for good space
gear.
Interestingly, water is a great absorber of radiation. We
could put it between the walls of a spacecraft and it could do a pretty good
job of protecting the crew and the electronics. Hydrogen gas might work as well; notice how water is just
hydrogen and oxygen. The sleeping quarters on the ISS are lined with impregnated
polyethylene as an additional radiation shield.
But what might work best? – human waste. A privately funded mission to Mars led by Dennis Tito plans to use the astronaut's own excrement as
a radiation shield by packing it between the walls of the spacecraft. Organic
molecules and water block radiation very nicely, and they’ll be producing more
shielding every day. It’s a strange thought that a Mars mission might be
jeopardized by constipation.
The ionsophere (80-1000 km altitude) is part of the
atmosphere of Earth that protects us from cosmic radiation. It consists of
ionized air molecules; the ionization comes from the Sun’s energy. What's an
ionized gas called? – plasma.
So we have a plasma shield around Earth – remember this as
it will come up again. The magnetosphere (a 40,000 nanoTesla field goes out hundreds of thousands of km) is produced by the spinning of the Earth’s metallic outer
core. It participates in the protection because the ions of plasma in the
ionsophere are charged, and electrical charges in a magnetic field produce an
electric field.
reacts to greater energies coming from the Sun and will plume out to be more protective.
All this protection comes from the fact that ions in plasma
are charged, and the magnetic field is charged – and like charges repel. So the
high speed electrons of the solar wind and the protons and heavy ions of cosmic
radiation that come close to Earth are repelled by the magnetosphere, the
plasma sphere, and most importantly by the electric field produced by the
interaction between the plasma and the magnetic field. The vast majority of
charged particles and waves are swept around Earth and merge again safely
behind us. Now that’s a force field.
Several research groups have begun to think about how this
could be mimicked on a small scale to protect astronauts in space. A 2005 project from NASA contemplated using vectran balloons covered in gold that
could be charged to positive or negative values. Placed above a moon base and
electrified, the balloons might create a magnetic bubble that would shunt
radiation away and produce a protected cavity underneath.
No one has thought more about producing a plasma shield than Dr.
Ruth Bamford of the Rutherford Appleton Laboratory in England. Since 2008 she
has been working on producing mini-magnetospheres that would buffer the small
amount of plasma in space; using a magnetic field to hold it in place and build
up its density. Together, they would produce an electric field just like the
Earth does, and this would shunt radiation and particles away from the
protected object.
held in place by a superconducting wire mesh. Unfortunately, superconductors
only work to produce a magnetic or electric field if below their transition
temperature. And even for the best of materials (YBCO and BSCCO) this is
somewhere in the range of -265˚F. If the mesh was exposed to the Sun in space,
it would be several hundred degrees at least. Better keep thinking.
A discovery in 2013-2014 brought the thinkers back to Dr.
Bamford's mini-magnetospheres. It was discovered that small parts of the moon’s surface are protected
from radiation. It turns out that these areas produce weak magnetic fields (few
hundred nanaoTesla), and those fields are holding the thin plasma of space in
place above them. The field concentrates the plasma, and together they produce a
protective electric field to deflect particles and keep the surface of the moon
at those spots from being irradiated. Irradiation turns the surface dark, while
these “lunar swirls” remain light colored.
Bamford’s group has built such a force field in their lab and predicts that a 1.5 ton apparatus could do the job in space!
But wait, there’s more. A plasma shield could also protect a ship
from high energy weapons. Plasma has the capability to absorb photons of energy
like from lasers or phasers!!! And since plasma has to be at a very high
temperature to keep the electrons from re-associating with the nuclei, being in space would help since there would be no air to carry
the heat away from the plasma. It would stay hot and maintain itself. In fact,
incoming weapons fire would reinforce the plasma state by adding energy.
Next week – we need to talk more about shields. We’re building
some pretty cool ones on Earth right now. And some using plasma are already here.
Contributed by Mark E. Lasbury, MS, MSEd, PhD
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