vol 4 issue 21

Frozen out of broadband

30 November 2009
By Juan Pablo Conti
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The Earth's southernmost continent is not kind to technology. Successfully getting data out of the many scientific stations dotted around Antarctica is not easy, as E&T finds out.

For each of the past 37 years, geologist Rudy del Valle has embarked on two expeditions to the Antarctic. Even on the Earth's least explored continent, few things surprise him anymore.

But in the winter of 2005, while in his Buenos Aires office at the Argentine Antarctic Institute's earth sciences department that he chairs, he received an email with a tiny but extraordinary photo.

"I had never seen anything like it," del Valle says. The picture, taken moments earlier by one of his colleagues at the Argentine Orcadas Base in Laurie Island (one of the South Orkney Islands or Islas Orcadas del Sur as they're known in Spanish) showed a frozen tsunami, a wave that had turned to ice just moments before it hit the shore close to one of the Argentine scientific stations.

Caused by a powerful earthquake with an epicentre only 30km away, the tsunami would have almost certainly buried the station had it not been for the large area of sea ice that was surrounding the island at the time which had slowed and ultimately stopped the wave in its tracks.

As I look at the rather small, 28kB picture on my screen, I can appreciate the detail of what he's talking about, but I could certainly do with a higher resolution version. So I ask for one. Del Valle laughs at me: "What higher resolution? This file as it is took ages to be uploaded from Orcadas."

I should've known better. One thing you learn quickly in researching a feature on communications systems in Antarctica is that if there is one thing that doesn't abound down there, it is bandwidth.

Despite occupying an area larger than Europe and India combined, the Antarctic continent is yet to be reached by one of the ships that lay undersea fibre-optic cables that have helped bring the rest of the world onto a high-speed global telecommunications.

Every phone call, every email, every video feed, every byte of data that is exchanged between Antarctica and the rest of the world relies on wireless communications relayed by satellite, and even that is troublesome.

Larger research bases tend to be equipped with more sophisticated communication infrastructure than smaller ones such as Orcadas. One of six permanent Antarctic stations run by Argentina, the bandwidth available at the site in 2005 was 64kb/s. And that's after assuming ideal reception conditions and that nobody else was sharing the portable Inmarsat satellite terminal.

To date, the only Argentine bases that have been equipped with an Earth satellite station are Marambio and Esperanza. In each case, a large dish acts as the main communications link between the base and the National Antarctic Directorate in Buenos Aires, supporting telephony, fax, Internet and television traffic.

Communications inside each base; between different bases; between a base and a field camp and between a base and a ship or an aircraft are mainly done via radio using HF, VHF and UHF frequencies.

The most robust communications network in Antarctica is probably that of Australia. The Australian Antarctic Division (AAD) has all four of its permanent bases equipped with their own satellite Earth station.

Called ANARESAT, the network provides a 24-hour communications backbone between the Casey, Davis, Macquarie Island and Mawson stations with the AAD's head office in Kingston, Tasmania. The available bandwidth to Macquarie Island is 256kb/s, while the other three bases enjoy 384kb/s connections.

Unlike typical Earth stations deployed in more benign latitudes, in Antarctica these structures need to be enclosed in a 'radome' (radar dome) to protect the dish from the unforgiving conditions. At the four Australian bases, each ANARESAT radome contains a dish measuring 7.3m in diameter. They 'talk' in the C-Band to a geostationary Intelsat satellite located over the Pacific Ocean.

The geostationary orbit in which the vast majority of the world's telecommunications satellites are positioned is not that practical for Antarctica. As you get closer and closer to the South Pole, there is a point where - no matter how close to the horizon you manage to point the dish - it is physically impossible to have "line of sight" to a satellite orbiting 36,000km directly above the equator.

Most research stations are lucky in the sense that they are located north of the 82° south where, for practical purposes, beam coverage from geosynchronous satellites ends. In fact, the vast majority of Antarctic stations from most countries are also based north of 82ºS.

But there is the unluckiest research base in the world: the US-run Scott South Pole Station, which - as its name suggests - is located right at the Pole.

Not to be deterred by the laws of physics, engineers from Raytheon Polar Services have found a way to link up with geosynchronous satellites from the South Pole.

The trick is to use very old satellites that are beginning to approach the end of their operational lifespan. In order to remain geostationary, all geosynchronous satellites must periodically burn fuel to correct their trajectory. Without these burns, the spacecraft drift slightly in the north-south direction, effectively forming a figure-eight loop.

Although the effect is a problem for true geostationary satellites, these out-of-control birds are a welcome development at polar locations where - at least for a number of hours a day - they get to see the satellites rising over the horizon.

Comms access

Until recently, the Scott station could use four such aging spacecraft (TDRS-F1, GOES-3, Marisat-F2 and LES-9) to transfer scientific data and provide communications access to the Polies, as the personnel based there like to call themselves, via two separate ground station radomes.

But the fragile nature of such networking arrangement means that any one of the satellites can suddenly desert the Polies without much notice. Take Marisat-F2. At the end of August 2008, a group of Raytheon engineers and technicians at the base celebrated the repair of a major fault in the gear system of the radome used to track the GOES-3 and Marisat-F2 satellites. This had allowed them to restore the base's communications window from under eight hours to more than 12 hours a day.

Less than two months later, Intelsat told them it needed to decommission and dispose of Marisat-F2. Just like that, two precious daily hours of bi-directional, 1.5 Mbit/s broadband access vanished.

A few years ago, the National Science Foundation devised an ambitious plan that - if carried out - would bring more predictable, 24-hour broadband to the remote Scott base. The South Pole Connectivity Programme would involve rollout of a 2,000-km long fibre optic cable linking it with the French-Italian Concordia Station.

Since this other permanent facility is located at 75ºS at the edge of the Antarctic Plateau, the fibre channel would give Polies access to proper geostationary satellites.

But formidable challenges remain to be addressed if this multimillion-dollar project - originally expected to be operational by May 2009 - is ever to go ahead. Even if preheating the cable before it is covered by snow provides enough thermal protection to withstand the required -80°C, you would still need to find an answer to the massive strain that the cable would be subjected to. Indeed, moving at a rate of up to 10m per year, the flowing ice in this region of Antarctica would inexorably carry the cable along with it.

Summer collection

The obvious logistic limitations that are involved in every aspect of Antarctic operations mean that anything that communications technology can help solve remotely is hugely welcomed.

William Ray, the sustainable-energy engineer with the British Antarctic Survey (BAS), says he can access the data generated by power and water meters installed at some of the BAS research stations from his computer back in Cambridge. "I can dial in into our network in Antarctica via satellite and see what's going on in real time," he explains.

Being able to see what's going on in real-time has become something of a revelation for those scientists who used to spend years in the lab of their universities or research institutions developing an experiment - only for their babies to be taken to a remote, inclement spot of Antarctica during the summer and be left there on their own for a year or two. Finding out whether the instrument had managed to survive the winter and record any valuable data required a great deal of patience.

Colder than Vostock

These days, it's very different. For example, the PLATeau Observatory is an unmanned, fully robotic astronomical observatory installed at Dome A (or Argus) by the Polar Research Institute of China in 2008.

At 4,000m above sea level, Dome A is the highest ice feature in Antarctica. It is probably the coldest spot on Earth. Although the lowest temperature ever recorded was -89.2°C in 1983 at the Vostok base also on the Antarctic Plateau, Dome A is nearly 600m higher than the Russian station. However, as it has only had an automatic weather station installed in 2005, the coldest temperature so far recorded at Dome A was -82.5°C.

Most importantly for the Chinese, American, Australian, British and New Zealand scientists who have their instruments collecting data there, Dome A is thought to offer the world's best astronomical observation conditions. So, apart from the purely astronomical observations that each instrument will be making, one of the key jobs of the project is to test the site's potential to host a large observatory.

Just like in the old days, most of the hard scientific data will have to wait until January every year to be personally extracted from the two redundant PC/104 computers running the show. However, each of the computers is connected to an Iridium satellite modem that gives the scientists remote control of the system and the chance to receive up to 20MB of data per day.

Part of that bandwidth is used to transmit a set of photos taken by four different Linksys wireless webcams. Updated every hour, the images let the astronomers constantly see how their instruments and the critical engine module are coping.

As for the outer space video feeds captured by the instruments, four specialised video cameras are used. Supplied by Watec, the cameras were previously tested for operation below -80°C. Except for occasionally de-icing the lens, they conveniently don't require any heating.

The USB solid-state disks from which both computers boot also had to be tested for low temperature and high altitude performance.

In general in Antarctica, you don't want to take any risks when it comes to thoroughly testing electronic components. Five years ago, a group of researchers from the University of New South Wales, Australia found that a flash disk that was rated down to -40°C "consistently failed if taken below about -10°C".

In their paper titled 'Robotic telescopes on the Antarctic Plateau', the scientists commented: "Somewhat paradoxically, a significant source of instrument failure in Antarctica is overheating."

That's right: overheating. Designers often concentrate so much on thermally insulating their gear to protect it against ambient temperatures of up to -80ºC that, when at the height of summer the temperature suddenly rises to a mild -30ºC, they have a big heat dissipation problem they hadn't anticipated. It's just another part of the challenge that is trying to do science in the world's coldest continent.

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GPS fix, the other way round

With its constantly moving chunks of ice, Antarctica is an odd place to pick to calibrate global positioning systems but a station on the continent is crucial to the development of GLONASS and, soon, Europe's Galileo systems.

Essentially a radio-emitting beacon, an instrument at the Belgrano II station is part of a global network of similar devices called DORIS (Doppler Orbitography and Radiolocation Integrated by Satellite). Each time a GPS spacecraft flies over a beacon, it receives a 'beacon fix', which it uses to figure out its exact location.

"The orbit of these satellites continuously varies, both horizontally and vertically," explains Argentine geologist Rudy del Valle. "This trajectory deviation is caused by the gravitational attraction exerted by the different mass distributions - the oceans, the land, the Moon - over which the satellite flies."

The beacon at Belgrano II is responsible for covering the Weddell Sea area of Antarctica. "The instrument is located in a seismically inactive zone - technically, a Precambrian Shield - which is a very stable area," says the scientist.

Such geological stability made the Argentine station the only one where the beacon could have been installed. Although there are two other bases around the Weddell Sea (Halley Research Station, run by the British Antarctic Survey and Germany's Neumayer III Station) they're both located on ice shelves, which by definition are constantly on the move.

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