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ANTARCTICA

MARISAT-GOES Antenna

Photos © 2004 Seth White

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This installation about 1/2 mile from the new station is where (nearly) all of the South Pole's off-continent communications go through. Five years ago, the South Pole's comms abilities were still very basic. As I understand it, there were only limited satellite communications (along with the HF radio for intra-continental use). This facility was installed three years ago and represents a quantum leap in data transfer ability.

One day while talking to my buddy Joe I met Eyvind Flater, the satellite tech for 2003-04, and he was kind enough to give me a tour of the facility today (1/27). Here he is with his racks of equipment, which are housed in the wooden structure to the left in the picture above.

Currently, there are four satellites which are used by South Pole for data transfer: LES-9, TDRS-F1, MARISAT, and GOES. Each of these satellites was originally positioned in a geostationary orbit, above the equator. In this position, they cannot be seen from South Pole. However, they are all getting toward the end of (or past) their expected lifetimes and running low on fuel. As a consequence, they have been allowed to drift out of their geostationary orbits into slightly different planes (but still geosynchronous). Thus, over the course of a day they will 'drift' north and south from the equator a few degrees, and this permits the South Pole to view them for certain daily intervals. Another unusual thing is that only one of these (TDRS) was actually launched as a communications satellite - the station is essentially piggybacking on the communications channels of the other three satellites. These antennas are for the TDRS-F1 satellite, one antenna for each of the two bands used. If I recall correctly, the S band is a two-way channel used for internet, voice, etc. while the KU band is a one-way channel used to transmit scientific data. This channel uses a custom one-of-a-kind modulator unit, and there are no spares. So if it fails, so much for that dedicated science data pipeline.

This platform supports the antenna used to communicate with MARISAT and GOES. The antenna moves approximately 90 degrees in azimuth depending on whether it's tracking MARISAT or GOES, and has a few degrees movement in elevation. Each satellite can only be seen when it passes 8 degrees south from the equator (i.e. it is right at the horizon from South Pole at this time). Each of them will then drift a few more degrees from the equator before heading back northward. So these constraints dictate when we can communicate with the outside world...and do other critical things like update personal webpages. As an aside, Eyvind mentioned that inside the little hut to the right of the dish is a system which will use meteorites to detect high atmosphere wind speeds. Meteorites ionize the atmosphere as they pass through, and the instrument will detect the velocity of these ions, which are carried along by the ambient winds. A neat idea...but I wonder how much data they actually get? Another oddball project currently going on here is a Mars rover which is being tested by JPL. The thing is a giant sphere with instruments inside, and the idea is that it just gets pushed along by the wind like a tumbleweed and sends back data from wherever it goes. They released a prototype from the station a few days ago, but unfortunately I didn't catch this. It took off and I guess it was working pretty well. But then the winds died down and the last I heard it was sitting somewhere out on the plateau. Hopefully it'll get back rolling along soon.

The backside of the antenna platform. Currently, the four satellites provide about 15 hours of connectivity per day. However, some satellites allow faster transfer rates than others. LES-9 is the slowest, partly because the antenna used for this one is just a Yagi antenna stuck on top of the dome (!).

Whew. I was sitting here pecking away at this webpage while an automated scan was running on the UV monitor system. I looked up and noticed the data was all zero (not supposed to be that way). So after a while, a malfunctioning solenoid was found to be the culprit. So now, 4 hours later, the problem is fixed, the instrument is happy again, and I can relax and finish this page while some more scans run. The work I am doing here had been going along without any problems until now...but I suppose it was too much to hope for to get away without ANY problems, right? Woe is me. I'm sitting in a new, well-heated building at the South Pole, with good coffee and good music, and I had to turn some screws and solder some wires. GREAT GOD THIS IS AN AWFUL PLACE! Anyway, this is another view of the antenna platform.

And yet another view, head on. When the satellites are up, the South Pole presently has a faster link to the outside world than McMurdo does. However, all the satellites are getting on in years and quite literally, any one of them could fail at any time...today, tomorrow, or 5 years from now. The future for South Pole data transfer is going to consist of two main things: a new station to use TDRS-F3 and a wideband Iridium system. The TDRS link is supposed to be built near this site. Pole currently uses the Iridium network for voice calls only, however work is to begin this winter on upgrading to a narrow band data transfer system. After that, the idea is to get up to a wideband system. The Iridium satellites are owned by Boeing, who bought them from Motorola. As a note, I originally heard (and then wrote here without checking) that Iridium is a constellation of 64 satellites, after the element Iridium which has atomic number 64. I got a note today (6/3/04) from a fellow named Bjorn who pointed out that the atomic number of Iridium is actually 77 and that the original design for the system was in fact 7 orbital planes with 11 satellites each. The plans were then changed to 6 orbital planes (with 11 satellites each, for a total of 66), but the name stuck.

The dish itself. This pic turned out pretty good.

A little ways from the hut, this *high tech* lavatory facility caught my eye.