250 years ago we began to build in microgravity,
not high up on some space station or on the Moon. But right here on Earth
using towers very similar to this one.
By understanding how these incredible structures work we can get
clues as how we will colonize the solar system and bring the final frontier
right to your living room.
The purpose of the Coop's Shot Tower, located in Melbourne's CBD was to
produce small spherical balls of lead; much like these ones. When used in
hunting, hundreds of these pellets are loaded into a cartridge, so they need to
be extremely cheap to produce. Regular manufacturing techniques just aren't up
to the task. Machining would take too long and is far
too expensive while, casting isn't accurate enough. So if these don't work,
how do we do it? That's where a shot tower comes in. Today the folks at
Ballantine Ammunition have agreed to show me how theirs works. We are really
lucky today, because this is the last shot tower still operating in Australia.
About three and a half tons of lead is melted inside this massive container,
high up at the top of a tower. Unfortunately lead fumes are pretty
toxic, so if we were melting today then I'd be wearing this safety equipment.
Our molten lead gets pumped out of the tank and poured through this sieve. The holes
are precisely the right size in order to produce the type of lead that we want.
As it passes through the sieve regular manufacturing ends, and microgravity
manufacturing begins.
When you spill a glass of water gravity pulls the water
molecules downwards, pushing those below out and forming a puddle. By removing
gravity, the internal force of surface tension is able to take control. It wants
to bring everything as close together as possible, which is why when an astronaut
spills some water, it forms a perfect sphere. The same is true for molten pieces of
lead, falling from a tower. By incorporating microgravity into the
manufacturing process, this tower produces over a million pieces of lead shot every hour.
All of this is possible in just three seconds of free fall. Now that access
to space is getting more affordable, what new materials might we be able to create?
The answer to that question lies within this building; the old Stock Exchange.
Back in the gold rush era, you could buy and sell shares in different companies.
If the company that you bough, say a gold-mine, happened to strike a
particularly rich seam of gold, then you could stand in to win a lot of money. Of
course while a lot of this is luck, there are some ways to cheat the system.
Here is how it works. You put a really fast runner up in
Bendigo with instructions to come and tell you if anyone finds gold. If they do
is you'll know this information first so you can buy lots of those mining stocks
and when everyone else finds out the information, then the price of those stocks
will increase; giving you a guaranteed profit. At the beginning this is working
out pretty well for you, but then your neighbour Bruce catches on to what you're
doing. He buys his runner a horse, now he's making all the money. In response
you buy a car; he buys a helicopter; you buy a fighter jet. It's an arms race of
who can transfer information the fastest. Fiber-optic cables are made to transfer
data from point to point as quickly as possible, but the technology is limited
by the need to add repeater stations every 50 kilometers or so to keep the
signal strong enough to get from end to end. This adds in a small but noticeable
delay. So what if we've removed the need for these repeaters?
ZBLAN fibres might be able to do this by using a combination of elements which allows a
signal to be transmitted with barely any loss of power.
However this eclectic mixture makes forming the glass fibers here on earth
impossible. Gravity pulls the heavy elements downwards which in turn push
the light once up. This promotes signal blocking crystallization. Forming these
fibers in microgravity means that we can make a perfectly homogeneous substance
without any of these imperfections. A single cable of ZBLAN fiber could send
a signal from Melbourne to Perth without any repeaters in only 14 thousandth of a
second. This is relatively easy to do and we know it works there is already module
on the International Space Station producing lengths of this fiber for use
in medical imaging.
A journey this has it's centuries ago in a tower
much like this one, is taking us to the stars.
This has been James Dingley from the Atomic Frontier. Keep Looking Up.