Satellite ready for launch

A new constellation

After setbacks and threats of cancellation, Europe has committed to building its own GPS system.

One night in 1609, Galileo Galilei made history when he pointed a telescope at the sky and realised that the Earth was not the centre of the universe. The 400th anniversary of his observations was supposed to coincide with an event that the Italian astronomer would have relished even more than the 'Year of Astronomy' tag that it also brought to 2009.

This was supposed to be the year in which the world's most sophisticated global satellite navigation system, named Galileo in the astronomer's honour, would be fully operational. Four centuries after Galilei looked into the sky to understand our place in the universe, 30 state-of-the-art satellites should have been looking down on us, their powerful beams offering answers about where we are now and how to get where we want to go next.

Instead, 2009 started - just as it will end - without a single one of the 30 satellites of the Galileo constellation in orbit. At one point in 2007 the whole programme seemed set to fail, following the collapse of the private consortium of aerospace and telecommunication companies that had been selected to build and operate the rival to America's GPS system.

Eventually, the European Commission took control of the project, making €3.4bn of public funding available and setting 2013 as the new completion date. It chose the European Space Agency (ESA) to manage the technical side of Galileo and to act as its procurement agent.

Javier Benedicto, the Galileo project manager at ESA, is confident this deadline will be met.

"Maybe it's normal to expect problems, given that we have to deploy so many elements on the ground and in space," he says.

"There will be failures, obviously. Some satellites will fail, and some launchers may fail, too. So we may have to repeat certain things, which will slightly delay our plans. But we're confident that by 2013 we will have a good share of the infrastructure in place and we will start providing services as of 2012 for a limited set of users."

Max Engel, a US-based satellite industry analyst with North Star Consulting, is less optimistic.

"There's nothing I've heard said suggesting that it's an impossible goal," he said. "It's definitely an ambitious goal, but I don't think it's one of those cases where, on the face of it, it's ludicrous. Now, do I think [the 2013 date] will be met? Of course not - when are these things ever met? I'd say 2015 was a lot more likely, given that these things always go wrong."

A civilian system

Ever since the late 1990s, when Europe started discussing the idea of creating and operating its own satnav system, critics have asked why Galileo needed to be built.

Designed in the 1970s by the US Department of Defense, GPS is still the only fully functional global positioning system. While its original purpose was strictly military, a less accurate level of GPS has been freely available for worldwide civilian use since the constellation reached full operational capability in 1995.

Galileo, on the other hand, has been conceived as a civilian system. One of the main arguments in its favour is that it will give Europeans independent and guaranteed access to a service currently provided by a foreign power. The risk that - especially in times of war - the US might decide to jam certain GPS signals and therefore compromise the integrity of civil applications is thought to be low. In 2000, US president Bill Clinton ordered that this capability of the system be turned off.

Yet, even if Europeans could be certain that America's GPS signals would never be interfered with, "having two suppliers of satellite navigation data would be tremendously valuable from an operational point of view," Engel says. "It means that you could do things like automatically landing airliners using satellite navigation data. If you were to utterly rely on satellite navigation, you just cannot depend on a single supplier. No matter how benign the US Department of Defense is, you simply cannot trust absolute life-and-death responsibilities to a single source."

Then there's the commercial argument in favour of Galileo. The EC is convinced that, even if the current €3.4bn price tag translates into further cost overruns (as many fear will happen) EU member states still stand to benefit from a global market estimated to be worth over €10bn annually by 2015.

According to Engel, though, there's a flaw in this argument: "From the beginning we have heard that, because GPS is American, then European companies don't quite have the same opportunities, [so] 'We'll create our own satnav system and that'll help European industry'. That may be true, but I've never understood why. It's not like the DoD is Microsoft and if you're not Microsoft you can't fully develop for Windows because, 'Oops! We forgot to tell you stuff'.

"As far as I know, the [GPS] standard is available to everyone. There's nothing that keeps a European manufacturer from producing a GPS device that's just as good as one designed by an American manufacturer. Conceivably, for military applications there might be some considerations, but it is still NATO, so I just don't see that. I just don't see a multiplier effect here."

This makes the American analyst suspect that the main justification for Galileo is not economic, but political.

"They're doing this because it makes Europeans feel tough," he says. "That isn't an evil thing and, if the European government wants to spend its money to puff up its chest and have a European satnav system, as long as its doesn't get voted out of office for it, then I guess it's a wise decision."

In-orbit validation

Galileo is currently going through its in-orbit validation (IOV) phase. It follows the definition phase (completed in 2003 with the approval of the system's basic specifications) and precedes the all-important full operational capability (FOC) phase.

As part of the IOV work, two test satellites launched by ESA (GIOVE-A in December 2005 and GIOVE-B in April 2008) have been providing space engineers with a mountain of data, which they're using to test the system in real conditions. They're also using it to draw up the specifications for the manufacturing of the spacecraft and associated ground infrastructure.

Galileo will have two ground control centres, one in Munich, Germany, and the other one in Fucino, Italy. Both are currently being equipped with the necessary hardware. "We have also deployed and are already operating between 20 and 30 ground stations around the world, from the North Pole all the way down to Antarctica," says Benedicto.

The next step of the validation process will be to launch the first four of the 30 operational satellites that will be distributed in three equally spaced orbital planes at a medium-earth orbit (MEO) altitude of 23,222km.

Benedicto says the four new satellites, which are under construction, will be launched in the middle of 2010 from French Guiana. "We are developing a new launch pad for Galileo in our space port in French Guiana. We are going to launch these four satellites with Soyuz Russian launchers, which will allow us to launch two satellites at a time."

Four is the minimum number of orbiting spacecraft that a global satellite navigation system needs to be able to provide exact positioning information at predetermined test locations.

50MHz bandwidth for greater accuracy

If there is one marked deficiency in the existing GPS, it is its poor accuracy and signal strength, as users familiar with the system will certify. Unlike the reservations that some critics have about the commercial or political benefits of Galileo, no one denies that, when it comes to sheer performance, the European network will be a step forward.

Galileo users can look forward not only to location fixes featuring sub-metre accuracy (a tenfold improvement over average GPS fixes), but also to better performance in mobile environments and close-to-real-time readings.

Behind this jump in performance lie two key innovations that Galileo will bring to the satnav market. The first one is the use, at the core of each satellite, of a passive-hydrogen-maser atomic clock, the most stable clock ever flown into space. The second innovation has to do with the powerful radio frequency signals that Galileo satellites will transmit.

"The GPS open signal has very limited bandwidth, and bandwidth is a limiting factor in terms of the accuracy that you can get out of a signal," explains Benedicto. "In Galileo, we are using new signals and new frequency bands, which were approved by the International Telecommunication Union a few years ago.

"We're talking about signals that are not in the 1MHz bandwidth range anymore, but in the 20MHz to 50MHz range. This much wider bandwidth will bring not only higher accuracy but also better performance in a mobile environment."

Benedicto says that a particular difficulty of satellite navigation is that the user is constantly moving, which means the tracking signal is permanently confronted with new obstacles and reflections. The ideal remedy? Using wider bandwidth.

Speaking of confronting challenges, Europe doesn't have much experience operating MEO satellites. In fact, up until the point ESA launched GIOVE-A, Europe didn't have any experience whatsoever in this orbit. So a large portion of the tests so far have been dedicated to studying the impact of radiation in this orbit on onboard electronics.

"GIOVE-A carries two different instruments to measure radiation of electrons, ions and protons in this orbit," says Benedicto. "With GIOVE-B we have added a third instrument. This has allowed us to collect a very important database, which is quite strategic for European interests, not only for Galileo but also for other missions.

"We have improved significantly our knowledge of the radiation environment in this orbit. This knowledge has confirmed and, to some extent, modified the model that we had on this orbit, and it is now used to drive the design of the four IOV and 26 FOC satellites. We are much more confident now about the effects of this orbit on the electronic components, and we know how to shield our equipment in order to sustain the radiation over the long expected lifetime of the Galileo satellites," he says.

While receiver equipment manufacturers are being allowed access to the GIOVE-A and GIOVE-B signals to help them design early prototypes, the bidding process to supply the 26 remaining spacecraft, launcher vehicles and ground-based components of Galileo is now in full swing. The winning contracts should be announced later this year.

Apart from the Russian Soyuz rockets equipped with Fregat upper-stage modules, ESA plans to use the Ariane-5 vehicle. All launches will take place from French Guiana, the only space port that Europe has with the strict security arrangements needed to protect the crypto units that will be onboard each Galileo spacecraft.

Once fully operational, industry observers expect the combination of the European and American satnav constellations (as well as what's usable of the GLONASS Russian system and other regional networks such as China's) to result in an explosion of new products and services.

"As soon as it becomes a multiple-system world, the game is changed in such a fundamental way that it will vastly expand the market over time," thinks analyst Engel. "If nothing else, the more satellites up there the better a fix you can get, by cherry-picking the best four satellites from whatever constellation is in view."

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