back to article Curiosity out of safe mode, doing science again

NASA boffins have diagnosed and corrected the glitch that forced nuclear-powered, laser-packing space tank Curiosity to rely on its spare computer. The rover is now using the spare, but the “A” computer is once again ready for duty if required. The craft has therefore resumed its analysis on the powdered samples of Martian rock …

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FAIL

cryptic missive

Thanks NASA, for trying so hard to keep my interest in the program. Maybe next time I'll not vote pro-NASA.

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Flame

Re: cryptic missive

I forgot this is the age of 5 second attention spans, where things only get funded if the result is a big explosion or the ability to slap an American flag down somewhere (in the name of Freedom(tm) of course).

Maybe the next rover should incorporate an automated tweeting service to splurt inane crap every five seconds?

"OMG wheelz r so drty LOL #newshoes"

And thanks to the average twatter intelligence level, garbled, corrupted messages won't even get noticed.

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WTF?

Re: cryptic missive

Muppet!

(AKA: Pigs iiiiiiiiin Spaaaaaace)

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Anonymous Coward

Re: cryptic missive

"Maybe the next rover should incorporate an automated tweeting service"

Too late, it's already on twitter (@MarsCuriosity). :-)

And before the jokes start, it's running a VxWorks Operating System, not Windows:

https://twitter.com/MarsCuriosity/statuses/314122748324626432

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Re: cryptic missive

Oh god.... only a matter of time now before all NASA false colour images are uploaded to instagram with a washed out "vintage" filter, lens flare and a fake polaroid frame...

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Re: cryptic missive

Searching for intelligent life on Mars 'cause there's bugger here down here on earth.

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Boffin

Re: cryptic missive

"Thanks NASA, for trying so hard to keep my interest in the program. Maybe next time I'll not vote pro-NASA."

If you're considering on changing your vote based on a science mission not being entertaining enough for you, you Sir are an idiot.

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Anonymous Coward

Wot no checksums?

Or better, a proper MAC (which would also prevent people other than NASA from sending it any commands at all...)?

Seems a strange thing to have to worry about in such an otherwise advanced bit of kit. Should be simple to guarantee that messages either get through intact or not at all.

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Trollface

Re: Wot no checksums?

Oh shush, or you'll restart the whole "thick ethernet could have handled it" donnybrook.

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Re: Wot no checksums?

All forms of error correcting code have a price in bandwidth and the more correction you need, the more you pay. There comes a point where it doesn't make sense anymore.

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Bronze badge

Re: Wot no checksums?

I'd say the price of bandwidth is cheap compared to a potentially bricked Mars rover costing billions!

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Boffin

Re: Wot no checksums?

Even the best error correcting codes fail in practice when the signal is drowned out by MASSIVE random noise output by the sun. It would be like trying to shout at somebody on the other side of a football pitch while Motörhead are doing a gig in between. I think you will find that quite tricky (this is why people text each other in the disco, instead of talking).

Now make the football pitch a few hundred million km across, and replace Motörhead's few ten's of kilowatts of power by 3.9x10^26 Watts, and you get the picture.

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Re: Wot no checksums?

The price of bandwidth doesn't enter into it. The equipment on Mars and on Earth, the distance between the planets and the position of the Sun fix the maximum total bandwidth.

If you really want round-the-Sun radio coverage, you shouldn't be looking at error codes, but at some relay satellites in Earth's orbit around the Sun, but lagging or leading Earth by a significant amount. Then between Earth and the satellites, one should always have line of sight to Mars.

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Anonymous Coward

Not talking about ECCs.

NASA already use R-S and convolution-based ECC on their transmissions anyway; I'm just talking about some kind of hash on the end of each packet. ECCs can occasionally decode with undetected errors, but the chance of any kind of noise corrupting a packet and then also correctly adjusting the hash is FAPP zero.

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Coat

Re: Wot no checksums?

"and replace Motörhead's few ten's of kilowatts of power by 3.9x10^26 Watts, and you get the picture"

i.e.: turn Lemmy down a notch?

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Headmaster

Re: Not talking about ECCs.

Okay so we have Reed-Solomon FEC and hopefully some form of trellis convolution coding as well on the stream at bit level but where are the longitudinal checksums (CRC32, CRC48, CRC64) across the packets at block level and what about the message integrity checks (MD5, SHA1, SHA256) at whole file level?

M

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The sun is a massively parallell random number generator, it'd suck if there was a hashsum collision

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Silver badge
Happy

Doing science with camera apertures.

We do what we must, because we can.

For the good of all us, except the ones who are dead.

But there's no sense crying over every mistake

You just keep on trying till you run out of cake...

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Big Brother

Ohh! Look!

Nice tyre imprints to the left of the wheels. They look just like tracks my car makes when I've driven across my clay type soil.

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Alien

Why has the B computer got it's own set of hardware if they never intended to use it? I suppose it's multiple redundancy; but it you're chucking this stuff millions of miles surely you want to use every available instruments as much as possible, and be able to control them from both computers, not lock it off in the "other half" of the system?

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Trollface

We can expect to see more such images,

No thanks. I'd rather see more images of Mars.

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Boffin

Tried to reply to some comment about coding...

Actually, Shannon's theorem says you can do better than some arbitrary error rate on an infinite message as long as you include above a certain minimum rate of bit correction according noise (assumed to be random bit flips) on the channel. In effect, whatever error-correction coding scheme you actually implement, there exist more efficient ones. So, no, CRCs are not the ultimate coding scheme.

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Terminator

Who cares?

Laser! Use the laser!

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