Saturday
23rd January
From
Michael Burton.....
Well
after a couple of days of brutal weather, the clouds have
gone, the wind has eased and the Sun has come out again, and
even the Hercs have started arriving again! Then there's been
the the steady chug of caterpillar tractors running up and
down the ice all day dragging giant snowploughs behind them
as they clear up the great snowdrifts that have accumulated
behind all buildings, and re-grade the skiway and other walkways
about town. Its gives those of us who are temporary residents
a little feeling for what it's like in winter when Mother
Nature is allowed to reign unchecked and the snow if left
to lie where it falls!
The
good weather could be seen as a sharp line of blue sky way
to the north this morning (that grid N) moving slowly towards
us with the wind. About noon the bisecting line between blue
sky and cloud was directly over the station, with at one point
the AASTO in brilliant sunshine and the Dome under cloud.
An interesting observation of a change in the weather system
moving unhindered across the continent.
The
first Herc in brought us a replacement PZT for the secondary
mirror of the SPIREX telescope, and its now installed, though
not without a few concerns as it doesn't seem to have been
manufactured exactly the same way as the others we have. I
guess we'll know fairly soon whether its going to work.
Al
Fowler is happy, which is a good sign for all! Abu is now
definitely on its cooling curve, and after 48 hours is getting
close
to the cryogenic temperatures we need it at if it is going
to function. Another 10 hours on the pump and it should be
there. The little extra load we placed on the system this
year has been enough to take the pump right to the hairy-edge
of what it can cool down, something Al was unaware of until
he tried. So it looks like we may have a working telescope
and instrument for the season!
The
AASTO, on the other hand, is definitely an unhappy camper
right now. The servicing crew have been and gone, and left
it without its power system on!! There has been some considerable
trouble with the cooling system, with the freon which is supposed
to circulate and remove the excess heat, leaking, and the
radiator itself being blocked. Our little portacabin on the
ice has been getting up to about +40C inside, while the windchill
outside was below -50C! Definitely very toasty inside, especially
in our polar clobber, and not good for the freon which goes
gaseous at these temperatures, thus exasperating the leaking!
In an attempt to fix the blockage by the trusty method of
wacking the radiator and pipe with a wooden stick it appears
that another valve was cracked causing freon to leak once
more! So the service crew have decided that drastic action
is needed, which is to take the radiator off completely and
bring the system inside for a thorough going over. Only, now
the Hercs are flying again, they have headed north on another
job, and wont be back till sometime in Feb! Charlie, our trusty
winter-overer has decided to look into the problem himself
and is now searching for leaks in the radiator by pumping
down on it, and running a helium leak checker over it, just
like you do for any cryogenic vacuum system! This might be
overkill for our system, but at least we should know everywhere
it has micro-pores in it afterwards!
Since
the Sun has come out again I decided it might be as well to
place the sunglasses back on the webcam, but ran into a minor
technical hitch. The hi-tech blocking-filter-removal-module
(BFRM) that Andre had designed (a piece of string with a bullbog
clip on one end which you pull through a hole in the back
of the camera mounting) worked great at raising the sunglasses,
but not so well for putting them back on again as they run
into the camera body! Well I discovered this at about 6am
today, which is about my bedtime round here, and I was too
tired to do anything about it. But fortunately Matt, who
wakes up about that time, spotted the problem and went to
it with a screwdriver, removed the plexi-covering around the
camera, fixed the sunglasses, and put it all together again!
A remarkable piece of polar engineering at work!
The
Orbcomm transmitter spoke! Matt's lashed together ground plane
aerial actually did pick up a signal with Matt running around
with it held on a stick as high as possible when the satellite
was at its near point to us. A test email message did get
out directly from the AASTO without going via the internet!
Not that we've quite got the system to a useful data transmission
rate, but its a start in making the AASTO independent of the
need to have a local ethernet available with which to communicate
with it.
Daniel
continues to investigate all kinds of weather conditions on
the SODAR and write up the definitive works on its use in
Polar conditions, as well as knock holes in the reliability
of any wind measurements from meteorological balloons! The
SODAR had developed a nasty squawk to one of its notes, but,
as mysteriously as it occurred, it seems to have cleared up.
I've
been continuing to play around with the data reduction software,
getting around to looking at some of the code that hopefully
will be used for our data reduction pipeline. This is a little
different to the code I've been using, and I've been wanting
to compare methodologies and results. Somewhat to my surprise
inside an elegant package I've found a number of simple errors
which rather mess things up as regards to getting results!
But I guess that's life when you're
dealing with software!
That's
all for now!
Michael
B
 
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