If you make your way 800 kilometres north of Perth you'll find yourself at
Murchison and at the largest component of the Square Kilometre Array. Now we
haven't made that trip; it's a long way to travel and we don't have permission to
film there. Instead I've come to the Perth Hills constructs my own radio array.
One thing we do have in common however are the flies. In the long term this is our
best chance at discovering an alien civilization but immediately there are
some spin-offs which might help reduce our electricity bills.
The next big exciting thing in radio astronomy is the Square Kilometre Array
it has a collection area of one square kilometer when you add each of the
different listening antennas together. Just like your pupil expands in order to
let in more light; allowing you to see in the dark,
by having this larger collection area we can receive much fainter signals. If you were to
add together all radio waves that we've received from space in the last 75 years
of radio astronomy then all of that energy would be less than I've just
given this feather by lifting it only a few metres above the ground. The Square
Kilometre Array is going to change all of that, collecting more energy than ever
before. We're all familiar with radios and the
older ones among us might also remember when they had long extendable antennas. This
is an actual MWA dipole used on the Square Kilometre Array, it's also known
as a Spider and you can sort of see why. Each these legs are just the same as the
antenna from our radios except they're listening in to something much much
fainter. I've constructed a representation of the different radio
signals that are spider might be observing. At the moment it's a bit of a
mess; things like human radio transmissions, exploding stars and
colliding black holes get in the way of the alien signal that we're trying to
find. So how do we isolate it? A star explodes off in that direction and the
radio waves come hurtling toward the Earth. First the Spider Antenna picks up
a signal next the Christmas tree then, Spider Two,
Spider Three and Spider Four. Let's collect those signals together to discover what
happened with the explosion. Here are all of the radio signals, but they're still a bit
of a mess. If we account for both the speed of light and that these were in
different positions we can start to make order from the chaos. Spider number one;
we're going to leave that in the same position. But the Christmas Tree One; we
know that that was 2 meters behind the spider so going to be moving it up to of
the time units- about 10 billions of a second. Next we have Spider Two; now that
was three behind it so it's move it up three time units- about 15 billionths of
a second. We're going to be doing the same to the other boards now. When we add in
these time delays a clear signal emerges. Moving around these planks and adding in
time delays is just the same as physically moving the antennas except
that when we physically move them we can only listen in on one direction. By
having the array pattern and using specific delays it can listen in on the
whole sky. Eventually the Square Kilometre Array is going to have over a
million receivers spread across both Australia and South Africa. In order to
interpret the data we're going to have to do something a little better than
moving around planks of wood; we're going to need a supercomputer.
I'm at the Pawsey Supercomputing Center located just outside of Curtin
University and the home of the Magnus Supercomputer; a machine capable of
unlocking the secrets of the Square Kilometre Array. Fiber-optic cables run
from the receivers at Murchison into the galaxies and Magnus machines. Time
delays added and calculations performed with the results being written to a storage
cluster had then backed up to tape. The supercomputers produce a lot of heat
which we needs to get rid of in order for them to work effectively. You can
see here some water pipes which are being used to keep the system cool; these
water pipes perform the same function as the fan in your computer- cooling down
the electronics to avoid spontaneous combustion. After heating from 22 degrees
Celsius up to 29, the water is then pumped into a nearby building where is
called back down to 22 and recirculated into the computers. Usually a supercomputing
facility such as this would use cooling towers to facilitate heat
exchange, but as you can see that's not the best option. Cooling towers work by
evaporating water, taking away heat away in just the same process a sweat
evaporating from your skin. Unfortunately once it evaporates this water is lost.
Perth just can't afford twice the 30 million litres year required for this
process to work. Instead of resorting to high energy intensive refrigerants based
cooling, Pawsey instead takes advantage of its unique position above the Mullaloo
aquifer. The water in this Aquifer remains at a constant 21 degrees Celsius
year-round. From a hundred meters in depth this cool water is brought to the
surface where then goes into the heat exchange building. Now at 23 degrees
celsius is returned to the aquifer. Additional reinjection points use cool
water to help manage heat redistribution. Zero water is lost and because the water
in the aquifer remains the same temperature year-round it works
regardless of weather and season. At the moment we have a really cool supercomputer,
but so what? A typical business will be spending in the ballpark of
twelve thousand dollars a year on air conditioning. For a skyscraper you're
looking at over a million dollars. We could be using similar techniques we
used to cool the Pawsey Supercomputer and apply them to normal air
conditioning. This isn't difficult to do we will just be rerouting the cooling
systems for the water that we already used to cool down the air. If we were to
do this we would saved so much money a year on air conditioning as well as severely
reducing the amount of greenhouse gases we emit when we produce
electricity.