Curiosity needs OS upgrade before getting down to science The Curiosity Rover will upgrade its operating system before getting down to serious science, NASA said today. The Rover's onboard computer has wimpy specs, boasting just: A BAE RAD 750 single-board computer with a 200Mhz Power PC CPU; Two gigabytes of flash memory; 256 megabytes of DRAM; 256 kilobytes of electrically …
If you actually want to know:
https://en.wikipedia.org/wiki/VxWorks
VxWorks is a major player in embedded systems. Spirit and Opportunity also used it, Sojourner used it, SpaceX's Dragon uses it. And NASA's done OS upgrades at 250 million km before:
http://news.bbc.co.uk/2/hi/science/nature/5022524.stm
Angry Birds has yet to be ported to it, however.
It's not difficult. To make components rad-hard you need to thicken the oxide (reduces the risk of punch-through and is more likely to survive the ionisation track of a cosmic ray scatter particle) and increase the surface area (thicker oxide means less capacitance, more area increases it, and you want the highest capacitance in your cell to reduce the chance of a small stray particle flipping a bit. ECC can only go so far.)
IBM have produced a range of industrial-strength PPC processors for a long time with thicker gate oxide etc., and military design just takes this further, along with the more exotic substrates like SoS which are better able to resist distortion and conduct heat.
There were also completely non-cmos processors using a bipolar technology, but the problem with them is that they use a fair bit of power just standing still as current is needed to maintain the logic states rather than voltage.
So "radiation-toughened" isn't really quite correct. Rad-hard components are fundamentally rather different designs produced on different production lines. They cost a lot more to produce, partly because of the low production volumes but partly because a huge amount of inspection and testing is needed.
The "consumer-grade" stuff isn't junk; just designed for a different purpose. If you want JAN-TXV components in your phone, you won't have to worry about lack of network capacity because only bankers will be able to afford them.
From the NASA Voyager site:
"Question: What kind of computers are used on the Voyager spacecraft?
Answer: There are three different computer types on the Voyager spacecraft and there are two of each kind. Total number of words among the six computers is about 32K.
Computer Command System (CCS) - 18-bit word, interrupt type processors (2) with 4096 words each of plated wire, non-volatile memory.
Flight Data System (FDS) - 16-bit word machine (2) with modular memories and 8198 words each
Attitude and Articulation Control System (AACS) - 18-bit word machines (2) with 4096 words each."
Words in this context being I assume 32bits.
Two reasons, reliability, as stated above, Radiation hardened ICs are a lot more expensive than normal ones, but the biggest one is that with the turn-around on these things, and the massive number of test cycles they will have put it through, its likely to have been designed a decade ago.
I suspect it is mainly to do with the fact this was designed so long ago, PLUS the low power requirements of lower power, since this ONLY has an RTG to power it, and if they want to keep using it as the RTG looses power it has to have low requirements...
But for the task, the CPU and memory is fine, I've worked with much less..
Also it uploads its data, it doesn't need to store it locally for long...
For speed when you have a 20-40 minute delay in commands arriving and being actioned, sitting around for a few extra minutes while the rover maps its terrain is not an issue...
You only need lots of RAM and ROM space if:
a) you don't know what you're doing
b) you're running Windows operating system.
I wrote real time embedded apps on a microcontroller in C with 128 bytes of RAM, I kid you not. Most RAM I ever had was 1.5KB. ROM space, if I recall, was something like 16K words with each word being 14 bits.
You seem to forget that there are constraints on the power budget of Curiosity. More flash memory equals less power for experiments, so there has to be a trade off.
Again, it isn't how much memory you have, but how you use it. Very efficient coding techniques get the maximum bang out of your hardware.
They have been fiddling with identical hardware back here on Earth since before the launch. They have found better ways of controlling the hardware. Upgrades aren't really a bad thing ... unless you are discussing shovelware, of course ;-)
Look up the concept of "watchdog timer". Trust me, embedded guys grok the concept of bringing physically unreachable systems back from the dead.
Also note that there are a couple of radio systems on board, all of which are under separate CPU[1] control and can *probably* be used to bring the main computer back online remotely, if needs be. Wouldn't surprise me if ordering one of the cameras to look "all the way down, and all the way to the right, snap picture & process the barcode" would cause the camera's CPU to shoot a master boot loader over to the main computer via a non-maskable interrupt. No, I don't know, but wouldn't you do something similar? Belt&suspenders (belt&braces to you Brits) is a good idea at astronomical unit distances ... especially when added weight isn't an issue.
[1] Small values of CPU, of course, but enough.
All true, and some of the computers on the Apollo program, have to be seen to be believed (core rope memory for example - and a switch controlled powersaving mode that would drop power usage from 70w to 5/10w). Not to mention extended mapped interrupts to memory sectors than were then used to reference a batch of further commands/interrupts...
However this does make me wonder, if they have been working with upgrades and the like over time the vehicle was in transit, would it have been too hard to provide an en-route upgrade path?
After all what would have happened if the thing arrived, landed safely and was/is unable to fully process the update.. thats one very expensive brick...
And then the console screen flashes:
Windows for Extraplanetary Spacecraft must now reboot to complete the installation. Please remove all media and click "OK".
That poor thing, just sitting there, all alone with no one there to click on the "OK" button.
Life in eternity.........
Waiting......................
"I really cant understand"
Quite.
How many times have you, or indeed anyone, written extremely complex software that was not only totally perfect from the get go, but in fact could not be improved upon in any way at all, being the embodiment of computer science perfection?
Next, how many times have you had to do sysadmin work on a computer that will never be physically accessible by anyone within its operating lifespan? Now, how many times do you suppose NASA have done just that?
>I really cant understand why the damn thing wasn't working fully on the ground I mean who the hell would >choose to do a remote upgrade over that distance! A little bit far for a mobile engineer to pop out to reboot the >damn thing if it doesn't go according to plan.
Anyone remember Traveller RPG? Computers there were pretty tine anh had a limited number of program slots..
Talk about life imitating art!
... they often can't get the software work done in time. Any delay means missing a launch window that's often 18 months to 2 years long. So, you leave it for in transit or during surface operations to deploy the final version, which you spent the entire flight time testing to freaking death in simulations and duplicate units.
And then there's the crazy story of Voyager, that, at the time they left, they *didn't know how* they were going to sequence the camera moves and panning of the spacecraft during the Jupiter encounter. All of that research and development happened during the many years it took to get there, with everything going perfectly when the time came.
VxWorks is designed for this kind of thing, but I don't think there's words to describe the ball-pucker that engineers must go through when they send a firmware upgrade to a computer 30 million miles away. I can imagine the rover forlornly sitting on the surface, with a little screen that's black except for the words "press F1 to continue" on it.
What's the worry over doing an update to a rover vehicle on Mars?
Think about it. Use a low bit rate to reduce the error rate. Store the entire update in a staging area on the target platform, CRC check it. If CRC does not match, it's simple, don't install the update!
Ground station on earth sends a message to the rover "Have you received the update error free?" Response message: "No, please resend block 27 of 2052". Block 27 resend commences. "Have you received block 27 correctly now?" Yes. Go ahead and update.
No real problem here at all. Biggest problem with be possible interference from radiation from the sun and cosmic radiation in space.
It's easy enough to test the update process on the ground on planet earth first.
VXWorks is regularly used in space craft, and it's so well tested, reliable, it just is not like Windows at all! It's a proper real time pre-emptive multitasking operating system that just bloody well works: Windows can't multitask properly.
There was a spacecraft that did experience one single issue with VxWorks, it was down to a semaphore issue, a way of communicating, controlling execution threads, they uploaded through the millions of miles through space a patch for it, so it's designed to do these upgrades, but rest assured they're extremely rare to do because the entire mindset around VxWorks is very different to Microsoft and the development of Windows operating systems.
Don't even think about comparing the reliability of Windows with VxWorks.
> A BAE RAD 750 single-board computer with a 750Mhz Power PC CPU
Not to nitpick, but the CPU is called the RAD750 because it's based on the PowerPC 750 processor, not because of its clock speed. It operates at a mere 200MHz per BAE's own component specifications.
Even better, BAE's press reports claim that's a full 10-fold increase over its previous generation CPU, the RAD6000, which powers Spirit and Opportunity, Mars Odyssey, and a whole host of other Mars craft and other spacecraft.
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