South Pole Report
by Michael Burton

In January 1994 we reached a significant milestone on our journey
towards an Antarctic observatory.  We deployed our first experiments to
the South Pole. No longer are we wondering what it will be like when we
get to Antarctica, instead our discussions now focus on what we will
next do down there.

One of my students, Jamie Lloyd spent 2 weeks at the Pole installing
our infrared photometry experiment (IRPS) designed to measure the
brightness of the near-infrared sky emission. I spent the following  2
weeks fine tuning the equipment and setting it up so that John Briggs,
the winter over scientist with the American Antarctic astronomy group,
CARA, could operate it and send us back the data.  This was my first
time at the Pole and, I must say it is the most incredible experience
to be standing on the Plateau gazing out on the endless, featureless
plain of ice, stretching into the distance, to be met by the brilliant
blue sky.  While it may be cold (the temperature steadily dropped from
-30C to -40C during my time at Pole), life is surprisingly
comfortable.  On the Plateau, there are only light, invariable breezes
which hardly affect the ambient temperature. In the brief time I spent
on the coast it was much more uncomfortable, even though it was 30
degrees warmer, as the wind blew up and dropped on short timescales,
markedly altering the temperature as it did.

The IRPS is now sitting on top of the AST/RO (Antarctic Sub-millimeter
Telescope and Remote Observtory) building at the Pole, sharing the roof
with the 60-cm SPIREX (South Pole Infrared Explorer) telescope and GRIM
(the Grism Imager, an infrared camera very similar to the AAT's IRIS),
an airglow monitor, and a heated cabin attached to a 15-cm telescope
supplied by amateur astronomer Bill Volna.  A few metres away one of
the COBRA (Cosmic Background Anisotropy Experiment) antennas is
measuring the cosmic microwave background.  Around the observatory site
the first 4 of the 800-m deep ice cores of the AMANDA (Antarctica Muon
and Neutrino Detector Array) project have been drilled and filled with
photomultiplier tubes and are now hunting for neutrinos that penetrated
the Earth at the North Pole.  A kilometre away across the ice, back
towards the main geodesic dome of the Pole station, the SPASE (South
Pole Air Shower Experiment) air shower array of the University of Leeds
is trying to pin down sources of cosmic rays in the Galaxy, and the
GASP (Gamma Astronomy at the South Pole) gamma-ray telescope is looking
for Cerenkov radiation from the upper atmosphere.  Behind the latter
two is the Clean Air building, operations centre for our second
experiment, the measurement of microthermal temperature fluctuations, a
joint venture with the Universite de Nice.

Perhaps not surprisngly the deployment of our two experiments did not
go entirely without a hitch. Both Jamie and myself were going pretty
well flat out during our time there. It would have been impossible
without the considerable aid of John Briggs who is now tending our
experiments, and several others that CARA are running. We had trouble
with broken connections, vacuum leaks and software but nothing we
couldn't eventually fix. There were many lengthy email messages back
and forth to Michael Ashley in Sydney, which had the added advantage of
'testing' the integrity of our vital communications link - as well as
Michael's patience!

Astronomy is now the major science activity at the Pole, and over the
summer around 30 astronomers spent time there working on all the
different projects.  About half that number were present at any one
time, and working in the AST/RO building was a little crowded at
times.  When you add the construction people who were still trying to
finish the building so we could use it, you can see that conditions
were not at their optimum. Still, since time has no real meaning at
Pole, the astronomers all seemed to naturally fall onto a night
schedule within a few days of arrival and as the construction crew
seemed to prefer working days, we usually managed to work things out
between us!  Our first measurement of the Moon caused great excitement
for John Briggs and myself. We set the filter to L (3.8 microns), and
scanned the tilt mirror from zenith to horizon while waiting for the
rotation of the Earth to bring the Moon through our 4 degree beam. This
was in part to provide an absolute flux calibration (though I'm still
looking in the literature in vain for any global flux measurements of
the Moon in the near-IR, if anyone can help me), and in part to
calibrate the pointing of the mirror. We weren't really sure how strong
the Moon's signal would be, given we were pointing only a few degrees
above the horizon into a very bright sky.  As the appointed time for
the Moon to appear approached, and no signal was apparent, we became a
little tense.  Suddenly the signal shot up, and lo and behold there was
the Moon at about 7 times the strength of the sky in a 4 degree beam.
We knew we had a working instrument!  Infrared astronomy started as a
science when Piazzi Smyth detected the heat of the Moon from the peak
of Guajara on Tenerife, and we were using basically the same techniques
in Antarctica 138 years later. Despite this,   I found the observation,
trivial though it was in many respects, as exciting as any observation
I've made with a new infrared camera on a 4-m! The last of the seven
continents finally has its own infrared observatory!  Piazzi Smyth's
expedition had cost the princely some of around pounds 10,000.
Considering over 100 years inflation I think the $30,000 it had cost us
to repeat the measurement is remarkably good value for money!

Setting up the experiment to measure the microthermal temperature
fluctuations gave John Briggs and myself a little Antarctic adventure
of our own.  It took 6 hours to raise up the sensors and their
connecting cables to the top of the meteorological tower, some 100m
away from the Clean Air building, and 25m above the ice.  The tower was
a little wobbly, and I must admit to felling somewhat queazy while on
top, trying to connect wires together with the temperature at 40
degrees below! John seemed quite calm, as though it was an everyday
activity, but, then an Antarctic winter-over explorer is not fazed by
such trivial matters!  Our first data from the tower was very
promising, with the sensors showing only small levels of turbulence.
Those 25-m up had about half the level of turbulence of those at 7-m
elevation.  However after a few hours the turbulence appeared to drop
to negligible levels and inspection revealed the sensors had frosted
up.  The very fine wire being used appears to be just the critical size
for nucleation of ice crystals.  The connecting wires and cables hadn't
frosted, and the mirror for the IRPS has remained clean despite being
left  uncovered for 3 months now, but the sensors themselves are frozen
over. We can melt the crystals off by applying a direct current to them
for a few hours, and then taking measurements for the next 3 hours till
they frost up again. But this process cannot be readily automated and
without constant attention the sensors are going to remain
encrystallized.  This is somewhat disappointing, though perhaps not
entirely unexpected.  It is one of the many facts of life in the
freezer which we are only going to discover and learn how to contend
with by going down the Pole and trying things out.  Working in
Antarctica is certainly a challenge, but it is something we can clearly
cope with given the right preparation in advance. We look forward to
next year's South Pole campaign!



Dr Michael Burton is Chairman of the Australian Working Group for
Antarctic Astronomy.  In collaboration with Dr David Allen from the
Anglo-Australian Observatory, Michael was one of the first astronomers
to use an infrared instrument, IRIS, and observe the massive young star
cluster at the heart of the Galaxy