Tuesday
12th January - Mostly Bad
From
John Storey.....
Most
of today's news is not good.
Last
night we had a meeting to discuss the PZT assembly behind
the secondary mirror. Although we were initially quite proud
of our design, Peter and Fred were able to point out some
rather serious problems with it. First, the length of the
aluminum rods on the end of the PZTs means that the weight
of the mirror creates a bending moment on the PZT when the
telescope is tipped. Secondly, the balls at the end of these
rods are forced to slide across stainless steel grooves. Thirdly,
because the backing plate is made of aluminium, rather than
Invar (our original Invar one was the wrong shape), there
will be a substantial sliding motion required. All this is
in addition to the lateral load that we are placing on the
PZTs through the weight of the mirror. In effect, the mounting
almost *required* one PZT to break in order to accommodate
the thermal contraction.
We
decided the best thing was to machine grooves into the end
of the aluminium rods, allowing the balls to roll rather than
slide. (IRIS II at the AAT uses a similar system.) It was
in disassembling one of the PZTs to do this machining that
we broke it.
If
we can't get a replacement we will instal the dummy PZT, and
basically be back where we were 2 months ago.
The
Abu cryo-cooler is still going ker-chug ker-chug, but to little
effect. Al Harper is bringing in a new cold-head: it will
take a week to instal and test. If it doesn't succeed in bringing
the temperature down we will have little choice but to cancel
the whole project.
A
final piece of sad news: Walter Wild, an adaptive optics expert
and astronomer from the University of Chicago, died yesterday
of a heart attack, aged 44.
Last
night the mail spooler (or name resolver or whatever) of magnolia
got jammed, meaning that none of my mail went in or out. Victoria
the unix she-guru fixed it this morning just before the satellite
set, and there was a rash of messages transferred but not,
I think, all.
Thanks
to some very helpful messages from mcba, jfm, Mick, Andre
and especially Thomas, we've solved most of the minor problems
we were facing.
While
I think of it, the last team here clearly made a big impression
on the station. I'm often being asked (mainly by the women),
"where's Mick, where's Andre, where's John?" (or,
"where's that big hairy guy, where's that cute eskimo,
and where's that Australian guy with the American accent?)
and I have to confess they've scattered to the four corners
of the earth.
Having
got to bed late last night after picking up bits of broken
PZT from the floor, I was awoken again at around six by a
D7 bulldozer just outside my tent. Apparently they'd decided
to rearrange the snow. Given that Antarctica is twice the
size of Australia and is mostly snow, they had plenty to choose
from and I cannot see why they couldn't have gone and rearranged
some other bit. I guess I wasn't in a very good mood anyway.
Then
they decided to fix the Rodriguez well that supplies water
to the station, using waste heat from the diesel generators
to melt snow. This meant we went into water conserving mode,
which means paper plates and plastic cutlery in the dining
room, just like being on a picnic.
The
psychologists are continuing to watch my efforts to grow to
love Windows 95. My attempts to actually print something today
came to nought. Maybe I shouldn't have disconnected myself
from the Microsoft Network by turning off the Microsoft Netware
tool that was insisting I impersonate someone else so I could
log into a Microsoft mail-server. As soon as I find the Windows
95 CD I'm back in business.
The
good news is that, with jfm's help, I've found out what the
other mouse buttons do! Namely, middle button: nothing; right-hand
button: bring up a menu to change the screen colour. Hey,
this is great, Bill! It's really useful having that on a mouse
button! I like to change my screen colour every 5 minutes;
much more often than I want to, say, print things. Oops, the
shrinks are writing stuff down in their notebooks again...
The
really funny thing is that *everyone* from PI AG (Deutschland)
to Mick to various people's kids sent messages saying: "of
course the bridge won't balance unless you include the extension
lead, which has about 5 ohms resistance". Well yes of
course I know that (now) and so I've taken the resistors out
of the strain-gauge preamp while no-one was looking and it
works perfectly and it's probably Ant's fault anyway.
The
good news today was that Michael Burton, Daniel and Matt arrived
this afternoon, along with the sodar. The sodar has been uncrated
and looks good; the sodarmites also appear to be in good shape
and ready for some hard work.
I've
had no success with the Orbcomm. It's all wired up and claims
to have spent the last 4 hours looking for a satellite. I've
suggested to it that it try looking in the sky, rather than
underneath buildings or hidden behind bulldozers but, even
with this helpful advice, it's having no luck. I've now taken
Andre's "short big" antenna and lashed it to a flag
pole. This brings it 3 metres closer to any passing satellite
than it was before, which might help.
Tonight
there are a couple of talks by a team of French and a team
of Dutch folk who are skiing their way across Antarctica.
I've decided to give the talk a miss partly because I want
to get on with doing stuff, and also I find it hard to fathom
why anyone would want to ski across Antarctica when it's already
been done. Particularly bizarre are those folk who choose
to walk, when skiing is a lot easier and being towed behind
a parafoil easier still. If you're going to be cold and miserable
for 6 weeks why not just lock yourself in a meat freezer and
listen to Spice Girls tapes. I look forward to meeting the
first group to roller-blade across the continent dressed only
in board shorts, T-shirts and back-to-front baseball caps.
John
 
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