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Spirit 'Will Be Perfect Again'
G. Holst writes "NASA technicians are preparing to wipe Spirit's flash memory clean of science and engineering files that have stymied its software. The fix, likely to be made Friday, could completely restore Spirit. "I think it will be perfect again," says the Mission Manager. Chalk this one up for earth!" There are numerous stories about Spirit and Mars: one describes being careful with rm -rf. Reader Tablizer sends in an interesting site: "I discovered Bill Momsen's website where he describes his experiences working on the first successful photographic mission to another planet: Mariner IV to Mars."
Woo-hoo!
Glad to hear Spirit will be feeling herself again.
Even perfecter. The next rover mission will be even more perfecter. Maybe even the perfectest!
These guys are about to wipe the memory of a robot on another planet and they're confident and casual. Just flashing the bios of my motherboard in my computer room causes me anguish and fills me with terror...
One has to wonder, is opportunity going to forego the same problems as spirit?.. As they are "identical" robots.. have steps been put in place to prevent the 2nd robot from "getting full".. I should certainly hope that we dont want this to happen again, as they might not be as lucky to regain it.
How come we're not awash with "Spirit was willing, but flash was weak" jokes?
VxWorks in my experience is terrible at memory management, and when you get close to the "edge" it becomes almost useless. Not just with Flash memory either. Even when managing a very large disk system I always try to keep at least 20% free.
"Dave, stop ... Stop, will you? Stop, Dave ... Will you stop, Dave ... Stop, Dave. I'm afraid ... I'm afraid ... I'm afraid, Dave ... Dave ... my mind is going ... I can feel it ... I can feel it ... My mind is going ... There is no question about it. I can feel it ... I can feel it ... I can feel it ... I'm a ... fraid ... "
They're saying mad-scientist-esque things like "I think it will be perfect again" and calling rocks "Cake."
They've officially lost it.
-n-
Apparently it was simply too many files and the FS ran out of inodes. Remember that they're constrained to a 256MB file system. It wouldn't surprise me if they used an 8 bit or 16 bit number for the inode count. (Ah, the joys of Vx(Doesn't)Works.)
On another note, does anyone know exactly what they're deleting here? While I understand that they need to get this mission underway, is there a chance they could lose valuable mission or navigational information?
Javascript + Nintendo DSi = DSiCade
The information coming in about the Rover's the last few days has been fascinating. I never really appreciated the kind of tech that went into these things. It really makes you sit back and think about how very far our species has come in the last 150 years. I mean Jules Verne was only begining to imagine landing on the moon while riding around England in a steam locomotive, now, 150 years later, we routinely launch things into orbit around the Earth, and land radio controlled machines on other planets to roam around.
This is truly a wonderful age to live in.
I heard the headline that "Opportunity has plunged into the atmosphere of Mars," and I couldn't help adding to this in my head, "as well as Spirit, Motivation, Job Prospects, and Hope."
"Teleporting Rodents with D-Cell Battery Displacement" theory -- IgnoramusMaximus (692000)
A chemist, an engineer and a computer scientist are passing through a vast desert in a car when suddenly the car breaks down.
"Goddamnit! There must have been some sudden increase of enthalpy in the cylinder!" the chemist yells, gnashing his teeth, banging on the steering wheel.
"Maybe the fan belt broke or the battery is dead or the wheels came off.." the engineer mumbles.
After thinking a while the computer scientist shrieks in a shrill, frantic voice:
"Let's just try getting out of the car and getting back in!!!@!"
p
They're deleting all the telemetry and science data Spirit's taken since launch. The OS is in the EEPROMS. With one exception, they can repeat all of the measurements & photos that will be lost. The exception: As one of the orbiters happened to fly directly overhead it took some atmospheric measurements; and, simultaneously Spirit performed the same measurement from the ground -- This would have given them a full thickness measurement of what was going on in the atmosphere at that moment.
Ok ok ok... chill out everyone... ;) ). In fact the whole system that they are using on the rover has flown quite a few times (VXWorks running on rad hardened PowerPCs with a VME bus for it's backbone).
VXWorks is not that bad (I use it on almost a daily basis). Every single OS has its problems. Before we all go and start calling VXWorks or Spirits software a crappy piece of code, you have to understand what goes into writing space qualified software.
This is not some thing you hack together over the weekend. In fact something you wrote for a space system over the weekend would be tested over a period of months and possibly even years depending on the criticality of the code. We're talking life critical system testing here. That means all paths for you code heads out there.
That said, even when you hit rubber to the road, there are always unexpected situations. Something that you didn't anticipate, a bug that made its way through under circumstance x. Hands up for everyone here who has written a complex bug free system right out of the gates. Anywone who just lifted their hand does not understand what a complex system is or a bug. Though stuff that flies tends to be pretty darn close to bug free.
We are dealing with many complex unknowns when we land something on another planet.
VXWorks is actually very popular with the space program. It's not perfect but neither is Linux (though someday it will be right
Trust me, the software running on the rover is not crappy. In fact, the fact they can bring it back to life like they did says a lot.
Released versions of VxWorks do not have protected memory. (The development version does.) So nothing is there to prevent overwrites by concurrent tasks, etc.
Those of you in the audience experienced in embedded systems know that this makes sense for embedded hardwar -- VxWorks or not -- for three main reasons:
Stuff running in such environments is damn near bug-free. It's not like, say, Mozilla, or even the Linux kernel, or even /bin/ls. These things get tested rigourously, not as an afterthought deligated to the junior programmer.
In systems which are allowed to fail once in a while, reboots are fast. There's no hard drive to spin up, no filesystem to fsck, etc. It can just go *click* and humans won't typically see an interruption in [whatever it was the doohickey was doing].
There's usually no point in memory protection. If the propulsion system walks off the end of a garbage pointer, mission's over. No real use in keeping the guidance system going; it's already on a ballistic uncontrollable arc. If some critical part of the super-smart pacemaker fails (see #1), there's no victory in digging the device out of the corpse and saying, see, this other critical part wasn't affected, thanks to the memory protection! In those cases, memory protection just increases the cost and size of a device, without helping anything.
Protected memory is good for systems which do more than one thing, and/or have parts which can die without killing the whole device (e.g., a desktop computer). And as I said above, some embedded OSes are added such protection for customers who want to adapt their technology to more general-purpose tasks.
You cannot apply a technological solution to a sociological problem. (Edwards' Law)
Other than the huge costs of transmissions equipment, does anyone know what kind of security they use to prevent hackers from doing this (like for instance some mischievous Russian space program scientist)?
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