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Exceptional Seeing At Dome C in Antarctica
Michael Ashley writes "A paper published in Nature
today reports on the exceptional
astronomical seeing conditions at Dome C (Coral link)
in Antarctica. Obtaining the data posed some significant technological
challenges, given that Dome C is uninhabited over winter. The
experiment was controlled by a PC/104
computer system that had to survive temperatures down to -85C, and
supervise the generation of its own electricity using a jet-fuel
powered stirling engine. The computer, running Linux, communicated with
the outside world using an Iridium
phone. The results are also covered in New
Scientist, and the Sydney
Morning Herald. Disclaimer: I'm a co-author."
I work with Diamond Systems PC/104 computers everyday. These systems are robust and the specifications for operating environments are crucial to applications such as these. Their ability to operate in extreme conditions, temperature, vibration, make them fit for such roles.
We've used PC/104 computers (running QNX 4.25) for everythign from Remote power stations, Fuel cells, even UAV's.
Harder.. Better.. Faster.. Stronger
But I've applied for a job down there (no reply so out for this year); anyone work down there and have any advice for getting a foot in the door?
Thanks
Vote monkeys into Congress. They are cheaper and more trustworthy.
Their assets were bought, very shortly before their satellites were supposed to have been deorbited. I don't recall who bought them.
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One experiment, ICECAM, relied entirely on a 5 kg pack of lithium thionyl chloride batteries. The batteries had to provide power for a year, so minimized the power consumption of the computer. The experiment only needed to take data every two hours, so we built a CMOS oscillator to power-up the computer for 30 seconds every two hours. We used MS-DOS 6.22 for the PC/104 computer since it boots quickly and was able to average 10 frames from the CCD camera and store them to CompactFlash disk.
www.bannination.com Two things float to the top he
The hard part would be coming up with a thermal control system that worked at both extremes, a hot summer day and the dead of winter.
Mea navis aericumbens anguillis abundat
However, I think Site C shows promise for imaging sites that are not in the right plane for Hubble to get a look at, or where the long winter night would allow for extended exposures...
Obligatory plug - please check out my online novel
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We astronomers refer to the twinkling of stars because of such seeing conditions as scintillation. I guess no one liked that word, though, so we dropped it to just "seeing".
Has to be the most hellish place on the surface of the earth. Dante's Inferno does in fact have the very heart of hell full of darkness and ice, in fact. A more miserable condition than any volcanic brimstone, I'd say.
I would just put the parts in an insulated box (not too insulated, but enough). As long as you never shut the thing off, you wouldn't have to worry much about the cold. Do it right, and you could probably keep the temperature of the whole system from fluctuating much at all.
My guess is that due to power restraints, the computer spends most of it's time powered off, or atleast in an extremely low power state.
Do American scientists use the Fahrenheit scale at all? I'm honestly asking. I'd presume that since the rest of the world uses Centigrade/Celsius and Kelvin, they'd stick to those scales too.
You'd think they'd have a cooler word for that...
As someone with myopia, I'd suggest laymen's terms like "20/20" or "20/10" or whatever (what would it be? "20/8") to describe the improved perspicacity available in low turbulence air. [BTW, I'm looking into Lasik and wondering just how good my vision could get...]
Or, you could perhaps express it in terms of
The ultimate, of course, is the Hubble, above the atmosphere. But the transportation and maintenance costs of the Hubble are considerably greater than Dome C.
BTW, nice work, nice web page. Thanks for sharing it.
"Provided by the management for your protection."
Can you tell us about the dramatic events of 17 May 2004?
By 17 May 2004 the AASTINO had worked remotely for 100 days in 2004, and then something went wrong...
The WhisperGen engine has a control panel connected to it using an RS-485 bus running on CAT-5 cable. The control panel contains a microprocessor, and the engine expects to communicate with it regularly (at least once a second). When this communication is interrupted, the engine shuts down and reboots its own microprocessor.
Unfortunately, this is what happened on 17 May. - the engine went into a cycle of rebooting every 40 seconds. Once the engine has stopped, we had a ten hour window in which to try to restart it before the 200AH lead-acid batteries would lose too much capacity and become too cold for a restart (which requires 15A at 24V for about 15 minutes).
During this period we worked feverishly to come up with a solution. Our first priority was to shut down all unnecessary power consumption in the AASTINO - we can do this via a series of Dallas one-wire switches which control power to all the subsystems. A call to the engine manufacturer came up with the suggestion that we wiggle the CAT-5 cable connection - we suspect they forgot that we were over 4000 km away from our engine!
The PC/104 computer was also on the RS-485 bus, and we reasoned that by rewriting the Linux device driver (which we had written in the first place, so we knew what we were doing) we could make the computer impersonate the control panel, and convince the engine that it should keep running. Fortunately, we had a snapshot of the communication traffic between the engine and the control panel from earlier testing in the lab with the manufacturer's MSDOS-based software. But with no hardware available to test our code, we had to modify the driver, send patches over the 2400 baud Iridium link, and rmmod/insmod the driver to try to restart the engine.
All the while, the internal temperature of the AASTINO was plumetting towards ambient, at about -60C. We first modified the driver to allow the link traffic to be analysed, and this confirmed the communication problem with the control panel. After several attempts at generating fake packets from the control panel, punctuated by breaks in the Iridium link and agonizing waits for the system to redial (it is dialout only, controlled by a crontab entry), we were unable to prevent the engine from rebooting.
We watched helplessly as the battery temperatures sank below the minimum threshold for engine restart. Over the next 24 hours we received the occasional connection from the AASTINO computer, but that was all. We are now hoping that the solar panels will be able to recharge the batteries suffiently to re-establish communication before the Dome C station opens for the summer.
This actually happens quite a lot and is one of the reasons large companies farm off risky things to spinoffs. Typically they wait for the spinoff to flounder AFTER it has sucked in huge amount of external capital and then at the last moment buy everything back for pennies on the dollar.
A good portion of certain companies DSL setups was done this way.
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What!
You'd be able to see a 5-degree circle of the sky centred on the north pole, and NOTHING ELSE.
Put on of those scopes on the equator and you're rocking.
p.s. Asteroids are mostly in the plane of the solar system, so something in the tropics is better.
Problem: you've been huffing on that Mercury, haven't you.