Antarctic Astronomy Diaries 2003/04

   

   
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Saturday, November 22, 2003

...but everyone knew her as Nancy

This morning started with the installation of the computer for Gerhard's precipitation monitor in the AASTINO. Unfortunately he wasn't able to quite finish the commissioning, as he is spending every afternoon slowly lowering a probe metre by metre into the EPICA bore hole and measuring the temperature every ten minutes. This sounds exceedingly tedious - I have decided I don't want to study ice-cores after all.

The sodar is continuing to ring out across the Station. Everyone is more or less used to it by now, although a couple of people have asked me if it's possible to change the tune. Surprisingly, no-one yet has asked if they can download the notes into their mobile phone to use as a ring tone. It would certainly set you apart from the crowd, and make a nice change from "The Pink Panther" and other favourites.

Our solar panels continue to shine (actually, they do the exact opposite) and are keeping the AASTINO powered up with an absolute minimum of fuss and bother. Part of the secret of having a happy relationship with a solar panel is to have a piece of electronics called a Maximum Power Point Tracker. This device matches the output of the panel to whatever the load happens to be, thereby ensuring that the panel operates at maximum efficiency all the time. Our MPPT is an outstanding example of the breed, Australian made of course, and has done an excellent job all year. Its only failing so far is that some of the segments on the numerical display have died, so you can't tell a "1" from a "7" or a "4" from a "9". However, as long as it knows what it's doing I'm happy to ignore the numbers and simply leave the decisions to it.

Anna is continuing to extract more and more information from our various computers, but with each step we seem to get no closer to understanding why everything stopped on July 1. One or more of the computers is clearly telling fibs - probably as a result of its real-time clock stopping in the cold and it getting confused about what the date is.

Lunch was lamb chops, which Jean Louis proudly assured me were Australian.

Today I started to work on the engines, in the hope that we might be able to get them started again - or at least diagnose whatever faults brought them to a premature halt earlier this year. While we can keep running on Station power all summer, by the end of January we need to have both engines up and running in order to keep the AASTINO powered after the Station closes in early February. (The solar panels will also contribute, of course, but they cease to be terribly useful once the sun sets in April.)

The problem with Sid, the first of our Stirling engines to stop working, was easy to discover. It turned out to be a burnt-out glow plug, correctly diagnosed by Sid's own engine management computer and very obvious to both multimeter and eye once the glow plug was removed. However, Sid's control panel continues to glower with the words "Locked out". While I have no idea what this means (and neither, it appears, does the manufacturer), it is obviously meant to be unfriendly and indeed Sid remains sullenly unresponsive.

Prior to attempting to start the other engine, Nancy, I checked the pressure of the nitrogen which the Stirling engine uses as its working fluid. Unfortunately the pressure was almost zero - clearly the engines do not appreciate being frozen and I can't say I blame them. I lugged our spare nitrogen cylinder in from the cold and allowed it to thaw out before bolting on a regulator. Needless to say, our spare cylinder was also completely empty. Antarctica is like that. However, we've been doing this Antarctic stuff for a few years now, and so it was just a matter of digging out the spare spare nitrogen cylinder, which upon thawing was found to contain 15 megapascals - this sounds like a lot and believe me, it is.

After recharging Nancy to the recommended 24 Bar (i.e., 24 times atmospheric pressure), I started the glycol coolant pump and looked for tell-tale bubbles in the coolant that would indicate a serious internal leak or, worse still, a cracked block. To be honest there were a few bubbles to begin with, but they quickly disappeared.

One of the really big chances we took this year was to allow the engines to freeze without first draining the coolant. Everyone knows that water expands on freezing (a strange, anomalous property of water; were it not the case life probably could not have evolved on earth) and when it does so it bursts pipes, engines or whatever else it is contained in.

However ethylene glycol, like almost every other substance, shrinks on cooling. Ergo, the right mixture of glycol and water neither shrinks nor expands. Even better, it forms a strange kind of slush like ice-cream, which can benevolently deform to whatever new shape its container wishes to adopt.

Armed with this information, and a test sample of glycol/water that we put in our freezer at UNSW and then poked with a screwdriver just to be sure, we abandoned our elaborate plans for automatic coolant draining mechanisms, and left Sid and Nancy to fend for themselves. Now we'll find out if this was a chance worth taking. I'll leave Nancy overnight to allow the O-rings to settle in under pressure before attempting a start tomorrow.

Speaking of starts, the Station mechanics now have the snowmobiles beautifully tuned, with the result that they not only start every time but are also rather fast. As the track between that AASTINO and the Station is becoming more established and firm, it's possible to explore the handling limitations of the snowmobiles which, frankly, are severe. They have so much back-off oversteer that the main rule for staying upright is never, ever, attempt to slow down. There's a tricky cresting right-hander just as you've straightened up from Robert Hill (the hill that the AASTINO is on) which I still haven't quite got right, but hope to by the end of next week.

I have decide to donate my suitcase, DOG, to the cause of science and will pack the sodar electronics in it for shipping back to France. DOG is an extremely expensive top-brand suitcase that I thought would be the answer to all my jet-setting needs, but which has turned out to such a disaster that it is now used only for shipping stuff back and forth to Antarctica. Its deficiencies are manifest: although it has wheels, they are so small and close together that it instantly falls over when towed on any surface rougher than plate glass; it is absurdly heavy, and has handles positioned with no thought whatsoever for the layout of a standard human body; the catch mechanism is a mechanical nightmare that appears deliberately designed to first trap and then shred expensive pieces of clothing; and it has a combination lock which sounds like a good idea because you can never lose the key, except that I can never remember the secret number. (Actually it's 609. If I write it down here then next time I forget it I can look it up on the South Pole Diaries web page.)

The only good thing about DOG the suitcase is that it is so hopeless, and such a chunderous colour, that no-one else on the planet bought anything remotely like it and it is therefore instantly recognisable on baggage collection conveyor belts.

At 5pm local time the Rugby Grand Final started. Anna couldn't resist using the Iridium phone at half-time, then full-time, then extra time, in order to find out the score. It's just as well the Poms won or she would have been really depressed as well as broke (Iridium phone calls cost a fortune). I tried to look depressed at Australia's loss, as this is apparently what was expected of me, but in reality I can't quite connect with the game. Anna tried to explain the rules but I got lost after the bit where a pawn can only go forward two metres unless tackled by a bishop in which case the rook is allowed to attempt a conversion...

The evening finished with an excellent talk by Eric Fossat from the University of Nice on the life-cycle of stars like the sun, together with a description of the upcoming solar eclipse. The talk was entirely in French, but with plenty of slides plus Eric's animated delivery it was relatively easy to follow.

John

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