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back to article Fiery bits of Euro satellite to rain down on Earth this weekend

Europe's GOCE satellite is due to come tumbling out of the sky to crash-land on Earth sometime next week – and nobody quite knows where it will land. The Gravity field and steady-state Ocean Circulation Explorer (GOCE) has stayed in its low Earth orbit for an extra two-and-a-half years on its planned mission, but came to the end …

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It's got wings!

The GOCE satellite actually orbits within the atmosphere --- it uses its solar panels as wings for lift, and an ion engine to counter drag. The wikipedia page has an awesome picture:

http://en.wikipedia.org/wiki/File:GOCE.jpg

So I suppose technically it's an aircraft (although now the engine's out of fuel, more of a glider).

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Re: It's got wings!

I thought it used the solar panels as fins to stabilise it, rather than wings that give lift?

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Ohhhh, The Irony...

Brought low by the very gravity it mapped in such extreme detail... curiosity and cat?

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Re: Ohhhh, The Irony... (x2)

Not only that, but they don't even know where their gravity experiment will land... would have thought the equations were well known at this point.

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FAIL

Re: Ohhhh, The Irony... (x2)

Of course not. It depends on how the atmosphere interacts with the satellite more than on the gravitational bumps.

Good luck extracting a prediction from THAT.

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Why didn't they...

...do a controlled de-orbit while it still had the juice for it?

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Re: Why didn't they...

It's because the ion engine can only exert a few millinewtons of force. So, the de-orbit is largly determined by the sun's activity changing the atmospheric pressure, the engine would give bugger all control over the landing point.

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Re: Why didn't they...

Because it would've needed several times more fuel than it was actually launched with, plus an extra rocket system, comprising at least 2 nozzles, plus various extra tanks, valves, pipework, control systems...

It's a bit like asking why a car doesn't have a built-in recycling system for when it reaches the end of it's life - and having to carry it around with itself everywhere. By that point, it would no longer work as a car.

However, the new polar MetOp sats are just going through a re-quote to have enough fuel to do this. In their case, they already have the rocket motors and the rest of the stuff for their mission, however the fuel to control de-orbit is still 2x what is needed for the entire 7 year mission. So it's a major upgrade in tank size and associated changes to the platform, but should allow the left over bits to land in the Pacific.

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Re: Why didn't they...

Perhaps you would if when the car was done it suddenly fired itself off the road randomly at 25,000 mph

- I think BMWs do

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Time to dust off ...

my Skylab protection hat ...

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Happy

Re: Time to dust off ...

You realise I'm now going to have to dust off an emulator and boot up Manic Miner (for the Skylab Landing Bay level)...

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Tin foil hats all round then !

as above

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If a bit lands in my garden ....

... can I keep it?

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Anonymous Coward

Re: If a bit lands in my garden ....

As long as it's not radioactive ;*p

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Re: If a bit lands in my garden ....

GOCE has no nuclear pile ... Greenz can sleep easy.

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Re: If a bit lands in my garden ....

If it lands in my garden, be sure to check my eBay listings.

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Black Helicopters

Re: If a bit lands in my garden ....

"GOCE has no nuclear pile"

That's just what *they* want you to think. We're all doomed... Still, my tin-foil hat will protect me just nicely thanks.

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Re: If a bit lands in my garden ....

You should be less worried about radiation from fallen satellites, but perhaps more worried about leftover propellant which can be quite nasty stuff. Although in this case, GOCE's ion engines used Xenon, which is inert and therefore harmless.

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Mushroom

Here's to hping it lands on Brussels!!

Or maybe Strasbourg....

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Re: Here's to hoping it lands on Brussels!!

Have an "o".....

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Anonymous Coward

Hope it lands in my boss.....

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There will be cake and then you will be baked

Doesn't this mean you have to get him to assume the TSA inspection position?

Otherwise it will just land "on" him.

(Hope the boss ain't female, otherwise....)

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Anonymous Coward

Re: There will be cake and then you will be baked

The TSA inspection also works with females. Just sayin'.

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Couldn't they use the Apollo 13 re-entry problem?

Based purely on the film Apollo 13, couldn't they have changed the angle of re-entry by a degree or two just before it ran out of fuel, thus causing it to burn up in the atmosphere much quicker? OK, not entirely scientific, but re-entry angle does seem pretty critical.

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Pint

Curious...

...I think my previous manager had something to do with the ion engine...Pint, Steve, if it's you. Long way from Oulu, though...

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So, where did it come down?

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Anonymous Coward

Oh the irony if..

It came down over Roswell, New Mexico.

Just saying.

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