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Author Topic: Spirit rover glitch explained.  (Read 4372 times)

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Offline FloidTopic starter

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Spirit rover glitch explained.
« on: February 22, 2004, 01:21:20 PM »
Well, Slashdot today links to the EETimes, finally detailing exactly what went wrong.  Not Wind River's fault; more of a NASA/JPL SNAFU.

Note that the "R6000" mentioned is not a MIPS chip, but the PowerPC-based "Rad 6000" board we already knew about.

...and apparently those "256Mb" of Flash were in fact megabytes, which makes sense once you read what they're using them for.  (Apparently repeat writes aren't a concern within the mission profile. ;))
 

Offline bloodline

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Re: Spirit rover glitch explained.
« Reply #1 on: February 22, 2004, 01:28:01 PM »
Facinating!

Offline KennyR

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Re: Spirit rover glitch explained.
« Reply #2 on: February 22, 2004, 01:33:51 PM »
"My daddy always used to say that if you wanted to put in a nail, you didn't do anythin' fancy, you just took a hammer and hit that son-of-a-bitch until it goes in there." - Soldier.

Which is my way of saying that I still think the NASA rovers were over-engineered.
 

Offline Tigger

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Re: Spirit rover glitch explained.
« Reply #3 on: February 22, 2004, 08:54:03 PM »
Quote

KennyR wrote:

Which is my way of saying that I still think the NASA rovers were over-engineered.


No, if they hadnt had the features in question we either would have had a rover get to mars without the additional features that were added or a system that couldnt have recovered from the errors as it has.   Why imply something is overengineered when it has allowed itself to be fixed from 150 million miles away.  
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Offline KennyR

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Re: Spirit rover glitch explained.
« Reply #4 on: February 22, 2004, 09:02:46 PM »
@Tigger

Making something self-repairing is not the same as making something so simple it wouldn't (and can't) have had errors in the first place. Russian engineering was always clunky and simplistic, but always very sturdy and practical at the same time, from T-34s to rockets. In some cases adding self-repair is even a detriment, not an advantage.

I'm very skeptical at the introduction of high level operating systems to probes at all - these are basically for the human interface. Remove the high level stuff and you can make the chips simpler and sturdier - not to mention cheaper.
 

Offline Glaucus

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Re: Spirit rover glitch explained.
« Reply #5 on: February 22, 2004, 10:14:50 PM »
Hmm...  Although I understand what KennyR is saying, and often do agree along those lines, I think I'm with Tigger on this one. If anything, it wasn't engineered enough! The software department should have had something better in place to handle a simple memory allocation problem! The system should have also had some sort of "safe mode" built into it's boot process, so that it could do the bare minimum to get itself up and running and communicate with Earth after experiencing a failed boot attempt.

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Offline Speelgoedmannetje

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Re: Spirit rover glitch explained.
« Reply #6 on: February 22, 2004, 10:35:53 PM »
Quote

Tigger wrote:
Why imply something is overengineered when it has allowed itself to be fixed from 150 million miles away.  
    -Tig

very VERY good question.
There's one thing: KISS (Keep It Simple Stupid)
and there's another thing: make hw and sw coping with EVERY circumstance. So you have to begin with calculating all circumstances. Kinda hard/expansive in space.
And the canary said: \'chirp\'
 

Offline that_punk_guy

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Re: Spirit rover glitch explained.
« Reply #7 on: February 23, 2004, 02:05:09 AM »
Isn't this why the term "mission-critical" was first coined?
 

Offline Cymric

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Re: Spirit rover glitch explained.
« Reply #8 on: February 23, 2004, 10:56:53 AM »
Quote
KennyR wrote:
Making something self-repairing is not the same as making something so simple it wouldn't (and can't) have had errors in the first place. Russian engineering was always clunky and simplistic, but always very sturdy and practical at the same time, from T-34s to rockets. In some cases adding self-repair is even a detriment, not an advantage.

I'm very skeptical at the introduction of high level operating systems to probes at all - these are basically for the human interface. Remove the high level stuff and you can make the chips simpler and sturdier - not to mention cheaper.

Interesting PoV, which I'm sure has been discussed to death in NASAs engineering labs. I think your approach has been rejected simply because the mission profile is too complex to be handled by what you call something 'clunky and simplistic'. It's simply an optimisation problem. Given a mission profile where small failures are a certainty, is a design made up from *lots* of simple, sturdy and stupid components better than a design made up from *a few* yet smart and self-repairing ones? Remember, lots of components weigh more than a few, and weight is an expensive commodity to carry around. And you are always facing the problem that in if in case of clunky and simplistic things *do* go wrong, you have just spent hundreds of millions of dollars to put some metal and advanced plastics on a big round rock.

My point: the problem is too complex to be dealt with by 'simpler is better' mantras.
Some people say that cats are sneaky, evil and cruel. True, and they have many other fine qualities as well.
 

Offline blobrana

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Re: Spirit rover glitch explained.
« Reply #9 on: February 23, 2004, 05:44:16 PM »
Hum, but simpler also means cheaper...
I think that NASAs agenda was towards having many low-cost missions, rather than a few high budget ones.

The use of `off the peg` and recycled parts must be a better solution to a cash strapped nasa.
But i suppose that this particular mission is very public and news worthy so i imaging that they did provide a lot of `redundant` features to the design...

Either way they have brought us marvellous discoveries...

Offline Tigger

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Re: Spirit rover glitch explained.
« Reply #10 on: February 24, 2004, 04:54:42 AM »
Quote

blobrana wrote:
Hum, but simpler also means cheaper...
I think that NASAs agenda was towards having many low-cost missions, rather than a few high budget ones.

This is a low-cost mission.  

Quote

The use of `off the peg` and recycled parts must be a better solution to a cash strapped nasa.
But i suppose that this particular mission is very public and news worthy so i imaging that they did provide a lot of `redundant` features to the design...

They used the same space qualed processor card they have used lately, used the FAA qualed version of VxWorks, which they have used in the past and got to reuse lots of code, the "simpler" design would have had to be custom and would have cost more to make.   Also when this situation happened we would have lost Spirit if it was a simple system.  The US is the only country to have successful landers on Mars, we've had 5, its silly to imply we are doing it wrong, when the other countries efforts have failed.  If we lose Spirit or Opportunity tomorrow, they will still have each been a huge success, and in all likely hood we'll be hearing from them for at least the next 45 days or so.  
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Offline Glaucus

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Re: Spirit rover glitch explained.
« Reply #11 on: February 24, 2004, 07:19:07 AM »
@Tig,

Didn't the Soviets/Russians succesfully land probes on Mars?

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YOU ARE NOT IMMUNE
 

Offline T_Bone

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Re: Spirit rover glitch explained.
« Reply #12 on: February 24, 2004, 08:09:47 AM »
Quote

Glaucus wrote:
@Tig,

Didn't the Soviets/Russians succesfully land probes on Mars?

  - Mike


I'm trying to find something funny to say about the "Red planet" but I'm drawing blanks!
this space for rent
 

Offline Speelgoedmannetje

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Re: Spirit rover glitch explained.
« Reply #13 on: February 24, 2004, 11:11:22 AM »
Quote

T_Bone wrote:
I'm trying to find something funny to say about the "Red planet" but I'm drawing blanks
hm, Mars as the god of war, the agressor. Mars as in Martians attacks the world (War of the worlds). Red, as being the color of blood, the color of the enemy.
And the canary said: \'chirp\'
 

Offline blobrana

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Re: Spirit rover glitch explained.
« Reply #14 on: February 24, 2004, 11:45:07 AM »
Mars has been particularly unlucky for the russian space program, and unlike the success's of the venerahttp://nssdc.gsfc.nasa.gov/planetary/venera.html spacecraft which landed on a more hostile planet...

And how they have tried...
http://www.geocities.com/goarana667/Marslist.htm