GPS
Growth has a bearing on national security
The US military owns the satellite network. But would it ever excerise its right to prevent civilians using it, asks Fiona Harvey
Published: October 8 2001 18:03 | Last Updated: October 8 2001 21:31
In 1592, the Dutchmen Cornelius Houtman and his brother Frederik were thrown into a Lisbon jail. Their crime was to attempt to smuggle Portuguese maps of the East Indies out of the country.
This fate was not unusual, for the time. Cartography was once regarded as a skill vital to national interests. Maps had to be smuggled between countries because governments feared such valuable information falling into the wrong hands.
This fear remained an obsession with the US military until the end of the cold war. In 1978, the US government completed the development of a system of navigational satellites.
Following lobbying by business, the system was partly opened up to civilians but a full service was jealously guarded exclusively for military use - at least until last year, when the world seemed without enemies, and civilians were granted equal access. Now that the US and its allies have launched a campaign in Afghanistan, will the electronic maps be taken back?
The Department of Defense in the US declines to comment on what will happen to the global positioning system (GPS) network following military action against terrorism. In theory, the US government has the legal power to switch off its satellites to civilian use at any time. It also has a motive to do so.
The usefulness of GPS to the military is hard to overstate. It is partly what enables the US to deliver its "smart" bombs, it allows military aircraft and ships to navigate to within a few metres and lets ground troops plan assaults.
Unfortunately, these capabilities are also attractive to terrorists. Now civilians have access to the system, people can buy GPS receivers for less than £100 ($150) and - potentially - use them for the same purposes.
In practice switching off the network to civilians is not easy. Just as maps escaped from their state-imposed straitjackets because they were too useful, so commerce has embraced GPS. The US haulage industry, shipping, in-car navigation systems, aviation and oil exploration rely on the technology. Leisure industries such as mountaineering depend on it.
As GPS has been made freely available by the US government, private sector alternatives have been slow to take off - which suits the US military, as it retains control over what is effectively the only such system. Most commercial satellite operators concentrate on communications and broadcasting.
The European Union this year gave the go-ahead for Galileo, a 30-satellite global navigation system, which will cost E3.25bn (£2bn). But the network will take years to establish - and companies will have to pay to use it.
The result is that GPS's commercial users currently have no alternative to GPS. But it is hard to blame them for not having a plan B: dependability is one of GPS's virtues. Knocking out even a quarter of the 24 satellites would not wholly disable GPS, which has been built to withstand enemy attack and orbital collisions.
It achieves this in several ways. Many communications satellites are in geosynchronous orbit - that is, they take 24 hours to orbit the earth and thus appear to hover over a single piece of land. Losing one satellite knocks out part of the map. GPS satellites are different, taking 12 hours to go around the earth. Each satellite is constantly moving across the sky when viewed from the ground and covering a changing "footprint" of land.
The satellites' orbits mean they cover a very large area and are less likely to be blocked by mountains. From any point on earth, a receiver can see between five and 10 satellites and sometimes as many as 12.
By collecting the radio signals sent from the satellites in view, which take about 0.06 seconds to reach earth, the receivers can calculate the distance to each satellite and deduce the user's precise location.
The US government can control the accuracy with which GPS signals may be read by degrading the signal using a technology known as selective availability. At first, selective availability was used to prevent civilians gaining access to fine positioning. It was turned off in May last year by order of Bill Clinton, then US president, with a view to giving commercial users a better service. Today, receivers can pinpoint a location to within 5 metres in optimum conditions, rising to 30 metres in less ideal conditions. Previously, the best they could hope for was 60 metres or more.
There is nothing to stop the US government reinstating selective availability and degrading the signal to an extent it decides would be compatible with both anti-terrorist goals and the needs of business.
Nothing, that is, except the safety of its own citizens. GPS technology plays a key role in the new E-911 regulations introduced by the Federal Communications Commission, which will eventually allow emergency services to pinpoint emergency calls made from mobile phones. Less precise positioning could mean lives lost.
There are also new commercial uses of GPS that rely on finer positioning. Mobile operators will rely heavily on GPS to enable them to introduce location-based services with their third generation mobile phones. These services - finding a restaurant, car park or cinema - form an important part of the operators' plans to develop new revenue streams from 3G, in which they have invested much.
There is an alternative to turning off the whole system or degrading the signal. It would, in theory, be possible to turn off coverage of certain parts of the globe. However, because of the satellites' non-geosynchronous orbits, that would be complex and perhaps costly, says Brownlee Thomas, analyst at the Giga Information Group.
In the end, it is difficult to imagine the US turning off GPS, or even degrading it, says David Baker, editor of Jane's Space Directory. "The genie is out of the bottle, as far as the technology is concerned. All the momentum built up during the cold war has been released and the energy is now sweeping across the commercial sector," he says.
He points to another formerly restricted technology that could prove valuable to terrorists. Spy satellites can provide photographs of the ground to a resolution of one metre.
At first, the military refused to allow such high-resolution photographs to be released to civilians, but eventually caved in to commercial clamour. They are now used in agriculture, oil exploration and other industries.
"These [photographs] were once within the reach only of superpowers - now any reasonably funded group of individuals can have them," Mr Baker says.
Perhaps the next area to fall to commerce will be the oceanographic data gathered by navy submarines. Still held closely by the military, this information could prove invaluable to oil and mineral companies and shipping. Mr Baker believes that this too will be released; after all, he points out, its collection was funded by taxpayers.
Perhaps the pressure of commerce is irresistible, whatever the threats to national security. As Miles Harvey notes in his book on cartographic theft, The Island of Lost Maps, the Houtmans, released from prison, went on to explore the Indian Ocean for what became the Dutch East India Company, beginning nearly two centuries' dominance of the spice trade.
news.ft.com |
