PC/camera combo puts scientist on cloud nine

Building an infrared telescope that takes detailed shots of galaxies requires lots of time, planning and nous. And for the University of New South Wales' School of Physics such a project starts small: with a 100mm cube PC/104 486 Intel machine buried seven metres under Antarctic ice.

The PC is, according to UNSW associate professor, Michael Ashley, "located about 1000 kilometres from anywhere". To be precise, the computer is positioned at latitude 75° 06' S, longitude 123° 23' E at the high plateau named Dome C. Dome C also houses the Concordia scientific research station being built by the French and Italian governments.

But the PC is only half the story. Attached to it "on a stick above the ice" is a digital video camera (naturally it is called IceCam) that takes shots of cloud cover every two hours.

The images of the cloud cover are important for the proposed Douglas Mawson infrared telescope (DMT, named after Australia's famous Antarctic explorer) that the university wishes to build and install where the video camera now stands. According to Paolo Calisse, who installed the IceCam in the summer of 2001, the video camera works on a basic principle: "If the sky is clear you can see stars in the darkness, when cloudy you can't." In other words, if Dome C proves to be a relatively cloudless part of the continent it would be an ideal location to install the DMT.

The DMT, which is still to be built, will have exceptional performance in the thermal infrared, with a sensitivity for wide-field mapping and for observing extended objects out in the universe. An infrared telescope is ideally suited to Antarctica. This is because the light from the galaxies is red-shifted into the infrared and it becomes "heat radiation". Consequently, to see the faintest galaxies, the sky that telescopes scan has to be as cold as possible. For this reason, the best location on Earth for infrared astronomy is Antarctica.

However, the School of Physics' plans to build the telescope took a set back last year when it narrowly missed out in the Federal Government's round of funding. Despite this setback, Professor Ashley is optimistic that the DMT project will go ahead, most likely as a French, Italian, or US project ("hopefully with some Australian input, since we have done a lot of the ground work"), and in the meantime his cloud observations continue.

The fact the UNSW research is taking place is due largely to the application of the School of Physics' bright ideas. The PC/104 box is buried so deep because at -57C, the temperature below the surface is warmer than the air temperature at ground level, which in winter fluctuates greatly and can be as low as -80C, enough to render the PC inoperable. The camera is also a hardy device. While it is only specified to run as cold as -20C, a simple test in Professor Ashley's lab put paid to that. "We shoved it in the fridge and it worked perfectly down to -80C". Which is just as well since there is no power available for heating the instrumentation.

The PC is fitted with a 256MB CompactFlash card, which stores the 12 images taken each day. Alongside the PC is a 5kg lithium battery pack, which is used to power the PC and camera. But to ensure the battery lasts until the following summer, when UNSW scientists return to retrieve the actual storage disk, the PC is fitted with the bare minimum of systems requirements.

With this in mind, Professor Ashley built a system that would only need to be turned on for about six minutes in a day, for about 30 seconds each time and then "hibernate for one hour, 59 minutes and 30 seconds". To do this he opted for a 486 Intel machine running a 100MHz chip. This set up was all that was required to capture the image and more importantly consumes only seven watts of power. It also transmits a summary of the data back to UNSW via the ARGOS (Advanced Research and Global Observation Satellite) system.

Given that Dome C is currently only a summer station, the IceCam computer has to run unattended without heat or power (apart from its lithium batteries) for at least 10 months.

Even the choice of operating system was important. Professor Ashley opted for DOS because it boots up very quickly. Most other operating systems would take too long booting up, and expend more power in the process he said.

IceCam is one of several UNSW projects under way at Dome C. Overall, Professor Ashley says he is happy with the progress, "So far the project is on track." The first year of IceCam data is currently being analysed and shows promising results. He said IceCam will need to stick around for a few more years in order to obtain a good statistical analysis of the cloud coverage in the area. In the meantime you can follow the progress of the IceCam at http://www.phys.unsw.edu.au/~mcba/icecam.

Image courtesy of Paolo Calisse

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