Slashdot Mirror
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."
Looks like making the ozone hole actually accomplished something.
Dome C is uninhabited over winter. The experiment was controlled by a PC/104 computer system that had to survive temperatures down to -85C
Now, that's a savage dome!
Free XBox, PS2
The experiment was controlled by a PC/104 computer system that had to survive temperatures down to -85C...
;-)
Wait a sec! =-P Computing equipment *loves* cold, as long as you don't have to worry about condensation. =-P In other words, it's not hard to design a system that can survive -85C. Just do a google search for Liquid nitrogen cooling. Yay for overclocking fiends who make it so you don't even need to mention computing hardware.
btw, there's a tom's hardware link on the results page. Check it out. There's a pic of a CPU mount covered in frost. That *can't* be good! =-P
Look at this photo. It is the author's Kyocera mobile phone with a web page showing the temperatures, memory usage and free disk space. Says battery temperature is -34.5 (is that C or F?)
2bits.com, Inc: Drupal, WordPress, and LAMP performance tuning.
What is "seeing"?
"Seeing" is a term that astronomers use to quantify the turbulence in the atmosphere and how it affects observations from the ground. The stars appear to twinkle because of the effect of this turbulence. In conditions of bad seeing, the stars appear to twinkle vigorously, and the images that you take with your telescope are blurry. In conditions of good seeing, the stars appear more stable, and you can take very sharp images.
You'd think they'd have a cooler word for that...
I would have to say Linux was the ideal choice in this case. Penguins are polar creatures. you know. I wonder how the Microsoft Rainbow-bee-man would've fared under such conditions.
An Indian-American Hindu committed to non-violent thought/speech/action alarmed by the global explosion of radical Islam
Hell, all that they had to do was stick a new Geforce and an Athlon in there and she'd be warm as toast ;)
You create your own reality - Leave mine to me.
The link that the submitter provided to himself doesn't work. The correct link is: Michael Ashley
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
Base camp: So how's it going there?
Dome C: Weh, Biwwy daywed me to stiwck my tung to the waw. Oh, and we'we outta beew....
"All great things are simple & expressed in a single word: freedom, justice, honor, duty, mercy, hope." --Churchill
A PC/104 is just a form factor. And provides standards for things such as environmental operating parameters.
CPU boards usually have an intel clone processor MACH86 or VIA Athena.
So they can run any OS your desktop can.
Harder.. Better.. Faster.. Stronger
PC/104 is a form factor and external bus specification, not a CPU type. It could have had any of many embeddable cpus on it.
What's a link?
Just stick .nyud.net:8090 on the end of your domain name (before the /) and it'll grab the content and cache it -- any future queries will return their cache instead of downloading from the original page. The coral links also work like your web browser and update the content when it is out of date.
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
so, how far is the secret nazi base from Dome C?
Stay away from the Norwegian camp....they dug up something in the ice and we've lost contact with them....
Last we heard, one of their sled dogs were running this way with a helecopter following it....
"Leo Fender was in a 'state of grace' when he designed the Stratocaster." -- Paul Reed Smith
So they went bankrupt, and no one would buy the system. It was a textbook case of a colossal business failure, and no one would touch it with a 10-ft pole. The judge hated to rule that a $5 billion infrastructure system burn up in the atmosphere, and luckily, at the last minute, Dan Colussy stepped in with a $25 million bid- less than half a cent on the dollar of initial construction costs, and swept it up.
Then what? The new Iridium Satellite LLC started cleanning up, which it's still doing. Very profitable. It turns out that, while it's impossible to recoup a $5 billion investment on a satellite phone system is impossible, recouping an investment 1/200 that size isn't so bad.
Can anyone tell me how to set my sig on Slashdot?
From the article in case it get's slashdotted:
To operate our experiments over winter, when there was no one at Dome C, we had several problems to address:
1. For hardware reliability, we wanted to remove all moving parts in the computers, i.e., no disk drives, and no fans. So we used a small PC/104 form-factor computer system with solid-state disk drives.
2. We had to generate our own electricity. We took two approaches to this:
1. 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.
2. For the experiment that obtained the seeing results, the AASTINO, we needed much more power, up to 400W, and we had to operate continuously, so we used stirling engines running on jet fuel. For software reliability we chose Linux, Redhat 9 to be precise. Software and hardware watchdog timers helped to ensure that the system would recover from most failure modes.
3. The ambient temperature at Dome C reaches a low of -85C during winter. Computers, and electronics in general, are not designed to operate at these temperatures. We took two approaches:
1. With ICECAM we had no reserves of power for heating, so we buried the computer in a crypt seven meters below the ice surface, at which point the temperature is stable at the yearly average of -57C. This is still outside the computer's specfication. Fortunately, a test in a low-temperature fridge showed that the computer and solid-state disks worked reliably at these temperatures. ICECAM's camera, a Watec 902-HS, had to remain outside, and tests shows that it was able to operate flawlessly down to at least -80C.
2. With the AASTINO, the stirling engines produced up to 6 kW of waste heat, which we utilized to maintain a comfortable operating temperature of about -10C.
4. Internet connectivity was provided by an Iridium phone, which acts like a 2400 baud modem.
5. The hardware and software had to be carefully designed so that we could recover from most problems remotely. There were no reset buttons to press, and no prompts to "click OK to continue".
The PC/104 computers we used were made by DSP Design, however it in unclear whether the company still exists, since all our attempts (using e-mail and filling out their laborious on-line enquiry form) over the past 6 months to have a simple technical question answered have received no response.
"Leo Fender was in a 'state of grace' when he designed the Stratocaster." -- Paul Reed Smith
I'd just go down there for a week, talk with people, and pass out resumes.
That was the turning point of my life--I went from negative zero to positive zero.
What?
I'm apalled that we are polluting Antartica with this radioactive material. What if the phone melts down? This could have devastating consequences for all of Antartica's residents.
paintball
The CPU is called the VIA C3 and the chipset is the VIA Eden. The "Athena" in your post refers to a Diamond Systems product name for the board which uses this CPU, not the name VIA calls their own CPU.
;-)
The "Mach86" you're thinking of is the ZFMicro ZFx86 chip. They are battling National Semiconductor, who produced these CPUs under contract for ZFMicro until ZFMicro was no longer able to pay their bills. Intel is not involved at all.
The other big PC/104 CPU vendors are Transmeta, STMicro (STPC), and AMD (Geode). Recently the Pentium 4-M have been popular for boards which don't need to support extended temperature.
PC/104 rocks for applications like this. Disclaimer: I work for a PC/104 company.
Okay I'm interested in seeing this jet-fuel stirling engine. How well does it work in extreme cold?
For those of you who may not know much about stirling engines, here's some information.
No moving parts to freeze? Can you say Hard Drive? Keyboard? Power Switch?
Last but not least. The user. You got to have some damn heavy mittens for -85C.
The article specifically says that they used solid-state hard drives. The system was operated remotely so I imagine no keyboard was used.
In addition, -85C was only the exterior surface temperature. One computer was installed under the surface with an average operating temperature of -57C. Another experiment was warmed by waste heat from the stirling engine.
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.
We're building a sub-mm polarimeter (Clover)to go to Dome-C (Dome-C is the best site in the world for sub-mm, being high, dry, cold and calm) starting now.
The total budget is 4.3M GBP, including new detector development, and the telescope will be collecting data from Austral winter 2007 onwards. This telescope will have better results on CMB B-mode polarisation than the Planck satelite mission, before Planck reports results, for about a tenth to hundredth of the cost. The Planck project has a 15 year head start. Admittedly Planck isn't designed to only make the measurements we are trying to make.
When something goes wrong, we'll be able to send someone out to fix it, and if someone invents better detectors, we can send some out to be installed.
Hubble is limited to the resolution of its 2m mirror, while optical telescopes on the ground are now reaching 10m (Keck), with sub-mm telescopes reaching 50-100m (LMT and GBT).
Hershcel/First will be the sub-mm equivalent to Hubble, and is limited to a single 3m mirror, while ground based sub-mm telescopes are using 64 15m mirrors spread across 60 km of the Atacama desert, simulating the resolution of a 60 km mirror.
as others have said, PC/104 is a board form-factor, but it's more than just a size (roughly 4" square). It also dicates the bus. PC/104 uses .1"x2 stackable headers for the ISA 8-bit and another, smaller, .1"x2 header for the ISA 16-bit bus. The two headers are stuck right next to each other. So you can have non-x86 processors on PC/104 but they must be able to read/control the ISA bus. So chips like the StrongArm must include a little glue logic as a bridge.
Additionally, there is PC/104+ which includes the 32-bit PCI bus in a 4x2mm stackable connector on the opposite side as the ISA headers.
There are more features to PC/104 but the size and bus signals are the most important.
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.
--- I do not moderate.
Freezing point of mercury is -38C (which is just about -38F) ... so it would be solid through much of the Antarctic winter.
When I froze mercury in the lab, it made a surface that wasn't optically useful -- lots of tiny bumps.
Also of interest: the century old Mt. Wilson 100-inch telescope used mercury bearings for the polar axis. In the 1970's, mercury pollution worried the operations staff; I don't know what was done about it.