Antarctic Astronomy Diaries 2002/03

   

   
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Thursday, January 09, 2003

Totally wired

Friday, 10 January 2003

It's now two weeks since we left Sydney, so perhaps it's time to recap.
Why are we here, and what are we doing?

Three of us from the University of New South Wales, (Tony, Jon and John) are at Dome C, Antarctica, site of a new French/Italian scientific station called Concordia. Dome C is at 75 06 06 S, 123 23 43 E, 3,200 metres elevation, and is very likely the best astronomical site on earth. We are here to build the AASTINO, a self-contained laboratory that will make measurements of the sky throughout the year. The camp at Dome C closes at the beginning of February, and will not re-open until November. In the meantime, the AASTINO will generate its own heat and power with a combination of two Stirling engines (running on jet fuel) and two solar panels (running on sunlight).

The AASTINO was developed by the Astrophysics Department at UNSW, building on experience gained with our AASTO at the South Pole. AASTO stands for "Automated Astrophysical Site Testing Observatory", and AASTINO is supposed to just be "Baby AASTO" but, like many babies, has grown to be bigger than the original.

The AASTINO will carry a series of instruments to help quantify just how good a site this is for astronomy. The first two instruments, which we will install in a week or two, will be SUMMIT and SODAR.

The many adventures of the UNSW team on their way to Dome C via icebreaker, fishing barge, dingy, helicopter and Twin Otter, are described in earlier diary entries. Now we're at Dome C, where it's daylight 24 hours/day The temperature is ranging from around -25 C down to -38C, but there's very little wind. The AASTINO has been constructed, and is providing us with a warm place to work. Currently it's just outside the Astrophysics Tent, about 1 km from the main station. It will shortly move to a recently formed topographic prominence known as Robert hill. Then, we'll fire up the Stirling engines, install the two instruments, and start taking data!

Now read on...

The electrician (Jon) has finished the wiring of our little fibreglass
house, and tomorrow the plumber (Jon) will come to install the cooling
system. After that, the heating engineer (Jon) will install the fuel
system and exhaust for the engines.

Tony and I have been working away on other aspects of the AASTINO, and
we're ready now to start installing the computers and electronics. I
spent quite some time connecting an "earth", or "ground" wire to every
piece of metal in the AASTINO bigger than a toaster. It is particularly
important that we properly "earth" the fuel tanks, to avoid possible
static electricity sparks that could start fire.

Fire is a constant worry in Antarctica, where the extreme dryness
increases both the ferocity and speed at which a fire can spread. Even
a small fire could wipe out our experiments; a larger one could destroy
the AASTINO. Not only that, but it wouldn't be very environmentally
responsible, and would also make us look like complete dills. Some of
our friends, and even perfect strangers, have questioned our sanity in
cooping ourselves up for 12 hours per day in a small fibreglass
structure containing 2 tonnes of fuel, in the middle of nowhere.
However, that's exactly what you do on a power boat...

Connecting electrical things to "ground" in Antarctica is a curious
problem. Snow is an exceptionally good insulator (both electrical and
thermal), and the nearest bit of "real" ground is 3.2 kilometres away,
directly underneath us. So ground to us means "all the big bits of
metal in the vicinity". The biggest things are the fuel tanks - so we
ground everything to them, rather than vice versa.

Tony amused himself for an hour or so making a sound-deadening gasket
for the SODAR. The SODAR is an acoustic radar, which emits beeps of
sound into the sky and listens for faint echoes from different pockets
of air. This tells us how stable the atmosphere is, and hence how
steady our astronomical images will be. Needless to say, it is
important to keep other noise sources, such as the Stirling engines, as
muted as possible.

Tony cut the absorbing gasket from a 2 cm thick slab of special heavy
plastic material that was recommended to us by Joe and John from UNSW's
Musical Acoustics group. It no doubt has a name, but we just call it
"meat". It has two remarkable properties. First it deadens sound
exceptionally well. Second, the first time anyone touches it they
immediately say "Yuck" and recoil in horror. It's hard to say why it is
so repulsive, but it's probably to do with the tasteless pink colour
combined with an almost belligerent hysteresis, together creating a "not
quite alive but if it were it would leap on you and kill you horribly"
impression.

Tony's first attack on the slab was with a sharp knife. This proved
tedious, and so a power jigsaw with a flesh-ripping blade was employed.
This didn't work at all, so back to the knife. Eventually Tony emerged
from the Astrophysics Tent triumphant, but we're all a bit worried about
what revenge the "meat" might take on us tomorrow.

Tony and I also descended into the "crypt" next to the Station to
remove the batteries and computer from "Icecam". The crypt is a
shipping container buried about 6 metres under the snow. There, the
temperature remains remarkable constant at about -55 C. It's therefore
a good place to put electronics and things that would prefer not to
endure the minus 80 C surface temperatures of mid winter.

Icecam is a small, automated camera that takes images of the sky
throughout the year. It is another UNSW instrument, and operates
completely independently of the AASTINO - relying instead on a pack of
lithium thionyl chloride batteries to keep it powered, and sheer will
power to keep itself operating in the cold. Icecam has been here for
the past two years, and is credited with making the first ever
winter-time astronomical observations from Dome C. The main thing of
interest that it tells us is how much cloud cover there is - obviously a
matter of great concern to an astronomer!

The Icecam camera head is mounted on top of a small shed above the
crypt. This year we're installing a new camera housing, one whose
design owes a lot to the storm-water plumbing industry.

Finding a Skidoo in the morning is always a challenge, and sometimes we
have to walk out to the Astrophysics Tent. Today, however, we had a
real treat - a ride in (or at least on) the "ambulance". The ambulance
is the best Skidoo on the base, and tows a marginally more comfortable
sled than the others. Normally it's parked outside the "hospital" (two
doors down from the kitchen) ready to rush off and rescue anyone who
might, for example, have set fire to themselves.

Slightly overcast again today, with a few high clouds and absolutely
zero wind. I have never before seen steam rising from a chimney, only
to form ice crystals and fall down again, like water from a fountain.
Dome C truly is a remarkable place.

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