Second Galileo sat to be launched

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Darth Tanner
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Second Galileo sat to be launched

Post by Darth Tanner »

linky in a skirt
Giove-B, the second demonstrator spacecraft for Europe's proposed satellite navigation system, is finally to be sent for launch.

The craft, currently held at a test centre in Holland, will be despatched to the Baikonur spaceport next week for a Soyuz flight in late April.

Giove-B will trial key technologies for the Galileo project, including the most advanced atomic clock to go into orbit.

Precise timing is one of the principal elements of any sat-nav system.

The passive hydrogen maser device on the new spacecraft will keep time with an accuracy of better than one nanosecond (billionth of a second) in 24 hours.

The European Commission and the European Space Agency, which together are driving the Galileo venture, hope such technologies can bring a leap forward in performance over the existing American GPS (Global Positioning System).

They believe improvements in accuracy and reliability can spark a multi-billion-euro industry in which receivers find their way into many more markets - from mobile phones to safety-critical applications such as guided trains and buses.

At one stage, Giove-B was being built in parallel with Giove-A, the first test platform launched in December 2005.

But the former's preparation was then hit by lengthy delays, including a major setback when a component blew on the spacecraft whilst it was sitting in a thermal vacuum chamber designed to assess the satellite's ability to withstand the extreme conditions of space.

The spacecraft will sit in a medium-Earth orbit
"It was a capacitor that failed; and you can imagine, you then have to stop the test sequence and have an analysis," explained Reinhold Lutz from manufacturer EADS Astrium.

"It took two or three months to determine what really was the problem, and then we had to dismantle the satellite to replace each capacitor. And we had to do it not just on Giove-B but on all our satellites.

"This exercise alone took almost one year."

After the repairs and modifications, Giove-B would have been ready for flight in December 2007, but has since had to wait for a rocket to become available to take it into space.

Giove-B's woes have to some degree mirrored those of the Galileo project as a whole.

The sat-nav venture came close to being cancelled last year when the private consortium selected to build and operate the system collapsed.

European Union finance ministers had to step in with a 3.4bn-euro public funding package to keep Galileo alive.

Galileo cannot truly proceed until the money is released, and that requires the formal agreement of the EU's legislative arms.

BUILDING THE SPACE SEGMENT OF GALILEO

2 demonstrators will test key technologies; Giove-A is in orbit now
In addition, 30 satellites are needed for the full Galileo system
First 4 spacecraft in the constellation have already been ordered
Remaining 26 yet to be ordered; they will be launched in batches
A mix of medium- and heavy-lift rockets could do the job
The timeline is challenging whichever rocket system is used

"What is needed now is a regulation, a legal instrument, which is necessary to allow us to spend the money," said Paul Verhoef, who heads up the Galileo Unit at the European Commission.

"The target is to come to an agreement even before Easter. It then needs some formal adoptions in plenaries and eventually it will enter into force. The date is not precisely known but it is expected to be May or early June."

He added: "It would come to delays only if in the next two weeks the [Council of Ministers and the European Parliament] don't come to agreement. But this is not expected."

A raft of technical issues have to be addressed if Galileo is to become a fully functioning civil sat-nav service that, unlike military systems, gives guarantees to users over performance.

Issues such as liability have to be sorted out; who would pay out, and how much, for example, if a Galileo failure was found to be the cause of an aeroplane crashing?

Contracts will be issued later this year to build all aspects of Galileo's vast infrastructure - from the satellites in orbit right through to the ground monitoring and control centres.

The timeline will be challenging. European ministers have insisted that Galileo should be up and running by the end of 2013. This will require launching a constellation of 30 satellites, the first four going up in 2010.

Giove-B will show whether the technology in these operational spacecraft is robust. As well as its atomic clocks, the latest demonstrator carries a signal generation unit, a complex processing centre that produces the all-important navigation signal.

This signal goes through an amplification system and is then converted to the three frequency bands over which Galileo will work. This will enable engineers to test the Galileo system across the full spectrum it intends to use to transmit its five sat-nav services.

"Giove-B is 95% identical to the final constellation satellites," said Reinhold Lutz.

"It is much more complex than Giove-A and can transmit the right waveforms simultaneously in all three bands."

Giove-B will leave the European Space Agency's research and technology centre (ESTEC) in Noordwijk, the Netherlands, on Tuesday, and fly to Moscow. It will then travel on to Baikonur, Kazakhstan, on the following Thursday.

The launch on a Soyuz-Fregat vehicle is timed for 0416 local time on Sunday 27 April (2216 GMT on Saturday 26 April).

Giove-B will be placed in a medium-Earth orbit 23,222km above the planet's surface.

It should begin its first transmissions in May.

Giove-A, produced by the UK firm Surrey Satellite Technology Limited, has worked flawlessly in orbit for two years.
Delays and massive governement subsidy in an EU program, say it isn't so. Its good that its making progress though, I'm impressed by how superior to GPS it is but still, seems a waste of money just to satisfy the anti-American crowd.

Although I love the quote from one of the connecting articles that Galileo is the "common agricultural policy of the sky".
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Post by Sea Skimmer »

Some of the claims of vastly superior accuracy for Galileo I’ve seen are based on nonsensical comparisons, like comparing theoretical Galileo accuracy with eight satellite lock ones to GPS accuracy with just 4 lock ons. What’s more, Differential GPS, which uses ground stations to correct for atmospheric distortions of the time signals is now available in a large chunk of the US and its accurate to within 10cm,. Wide Area Augmentation System, which also used ground stations, gets accuracy to within 1 meter, but over a way wider area (pretty much North America) then Differential GPS covers. In fact even some cell phone and car GPS systems tap into this kind of technology, using the cellphone system its self to provide additional data to the GPS unit, I can’t quite remember how that bit all works though.

Anyway, the limited advantage Galileo will have will be wiped out when the US starts orbiting Block III GPS satellites from 2009 onward. Funny enough Block III was also delayed, but not by as much. Galileo was supposed to be ready long before Block III was, but now it may only have a 1-2 year period of trumph.

What’s more, since these new GPS satellites wont have selective availability as a feature the main justification for a purely civilian sat nav system (fear the US military would turn it off in a war) is being eliminated. But hey, if Europe wants to pay for it I’m all for it, two systems will increase reliability in the event of bad solar flares or ASATs knocking down satellites, and receivers which work off both systems (not sure if it will be simultaneous) are already planned.
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