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Hubble's Computers Upgraded
MRcow writes "A story at ABCnews.com says the Hubble Space Telescope that was recently repaired by the crew of space shuttle Discovery is having its computer system upgraded. The new system will be 'three linked computers that run on the Intel 486 microchip.' It says older processors are used because they have to be tested for radiation and such. That makes me wonder if the computers are going to be "linked" and if so, how? Maybe a Beowulf cluster on Hubble? Talk about 'geeks in space'." The processors on the Hubble are being upgraded from what I understand are 1980s versions. The new hard drive is going to be a whopping 10 gigs with three 486 processors. The processors and drive have to be specially shielded and made to handle heat/cold extremes.
Hasn't Hubble been running a 386 for the last couple of years?
Where can you get a brand new 486 chip these days? (yes, after their inhouse testing)
You can get bus mastering ata controles, that have their own bioses, that can handle any ata(pi) device. Anyway, they are probibly using a scsi drive + controler
Well, if the portable pentium laptop fails, it isn't a critical system, so really no big deal. If the main landing computer fails on the shuttle, it would be a very big deal.
Also any laptops brought up are subjected to the stresses of space for only small periods of time since most shuttle missions are a period of days. Of course this could change if the space station is ever completed. The hubble telescope, and the shuttles were designed to spend years in space.
In the amateur radio world, a lot of repeaters are still controlled by Commodore 64s even today. Why? It's not just because they're dirt cheap and still relatively easy to find. For one thing It's cold at the tops of mountains. Blue ass cold! Brrrrr! -50F, snow, high winds (wind chill can go to -100F) and the little block shacks that house the equipment are NOT heated. Hard drives have problems when it gets this cold. The oil in the spindle tends to solidify. Same with the cooling fans. Of course, as we all know, fans stop turning after a while anyway due to dust build-up. And frequent maintenance is too expensive of an option due to remote location. (Many towers are reachable only by helicopter). A C64 on the other hand, has no hard drive, no fans, all code can be burned onto a rom and plugged into the cartridge port, in short, no moving parts whatsoever. Since there's no such thing as a PC with no moving parts being made anymore, older computers are actually FAVORED for these rough operating environments. Modern PC seem to get more and more fragile and delicate as time goes on.
The last time a repair mission went up, they upgraded it to a 386. I don't know what was in there originally.
I used to work at Nat Semi. Our job was to stress test the chips that came off the assembly line. Tested chips went into one of 3 bins for final labeling. The best chips went into the "Mil-spec" bin, The average ones went into the "Standard" bin, and the 3rd bin, was unofficially known as "Radio Shack". You figure it out.
Hard disks are designed to work under earth gravity and don't they use air between the head and the disk so that it does not crash? How can this operate reliable in space und Zero-G and in Vaccuum?
NPR had a comment, that pretty much boiled down to upgrading from a 286 to a 486, same mHz all in the hardware, no disks. Still sticking with the 486 because it could handle the rigors of space.
Cause Beowulf clusters rock ass all over Windows!
Since it's not doing anything important, NASA does not care what the laptops do. Besides, they can't tell what caused the crashes, the radiation or the Windows!
What drive are they using?
Very simple (the linking)
Computer A) 1+1=2
Computer B) 1+1=2
Computer C) 1+1=3
The system knows that system C is failing.
It's a standard way that NASA does things. Everything in 3's. Even the Gyros. 2 gyro systems, vertical and horizontal, each system had 3 gyros, total of 6. The Hubble went into a sleep state then 4 of the 6 gyros failed.
Essentially all of the Hubble data must be transmitted via the DoD's TDRSS conduit. I'm guessing NASA pays big bucks to do so, but a more serious problem (for NASA) is that DoD gets priority which causes NASA all kinds of scheduling grief. By doing some of the data processing on Hubble and buffering lots of data for burst transmissions when TDRSS is available, Hubble is much easier to use and requires fewer people to manage.
Total absence of knowledge. Modern chips have higher heat sink requirements because they have a higher current density [Amps per square unit of conductor] than the older stuff. They also have more total current consumption due to higher switch count.
Really old stuff used to produce say 1.5 Watts, modern 7 Watts and above. For a desperately thin piece of crystal with an area the size of the printing on your keyboard, this is close to the bone.
Overclocking. Yeah, right. [Sarc.]
Separating products rolling off of the SAME assembly line based on stress test performance is standard practise and is done all the time. NiCd Batteries? Some store more charge than others because not all batts are chemically identical even coming off the same manufacture process. The 850 mAH cells are labeled "high capacity", the 600mAH cells go to Everready. 486s fail the FPU test? Presto! They're sold as 486SX chips. The back side of 5.25in "double sided" floppies have errors? Sell them as single sided floppies. Those SIMMS become unreliable at 60ns? Sell them as 70ns chips. The point is that post-manufacture evaluation and reclassification of products has been going on for a long time and will continue to do so.
Why should I not expect to see the same practise used with current CPUs?
3K is the temperature of a blackbody with the spectrum of the cosmic background radiation. The temperature of an object in space will be a function of the radiation and light impinging on it, and of course any power of its own it's trying to dissipate.
An inert object shielded from direct sunlight will get down to maybe 100K. Sunlight will heat things up rapidly.
A modern processor chip without active cooling would overheat. Remember, standard heat sinks and fans won't work too well..
There are 3 sets of gyros, each with 2. The vertical, horizontal and the straight into your face (or as we call it, the Z axis)
Understanding radiation's effect on silicon requires quite advanced degrees, which I don't have. But I do work on a small satellite project (here). So I am familar with the results.
Over the long term, radiation exposure causes the circuitry to slow down. In the short term, there are two things that can happen:
Single event upset (SEU): When a radioactive particle penetrates the silicon, it can cause a bit to flip. Corrupting memory, while annoying, generally isn't fatal.
Latch up: this is dangerous. Latch up essentially causes a short circuit and can destroy the effected circuit.
Depending on the manufacturing processes, a chip may be more or less succeptable to these damages. 386's are tremendously resistant to radiation damage, even the commercial ones -- much more than 486's.
As for why using a 486? History, and time scale. As was mentioned elsewhere, these projects take years. Even my project has been going on since early 1996, and we're a considered a very small project.
History means that the project has been used for a long time and that its known to be reliable and bug free. You don't want to send an overly complex, new chip into space. If something breaks, you're screwed. It can be nearly impossible to force a reboot of a space-based computer. A lot of time and money is spent researching which chips have been used in space before. No one wants to be the first to try a particular chip.
For comparison purposes, my satellite uses two 80186-12 processors, which we're running at 10MHz to compensate for the slow-down effects of radiation. It's tough to deal with a slow processor, but at the time the satellite was designed, it was the best choice for us. These processors cost us $400/ea because they are "mil-spec."
In Space everything goes very slowly and you don't need a lot of processing power for housekeeping things like attitude control, telemetry, etc.. A slow 486 computer is totally adequate.. Better use an old slow CPU, with simple software instead slowing down a fast CPU with over complicated software which no one really understands anymore. Look at the increasing rate of these disaster (including Mars) caused by software/computer "glitches". Even simple appliances today embed so much processing power that subtle malfunctions of these devices become an every-day occurance. In spite of the large number of units produced there never seems to be the time to fully debug the units to make them entirely reliable. I am not speaking of computers; Bill Gates has managed to reduce the expectations of the public to such a low level, that if a program runs for two hours without crash, this is considered an anomaly. So this raises the question if spacecraft these days do not suffer from the same syndrome with the added complication that testing under the best of circumstances can never approach the amount of testing appliances will see before they hit the public. And invariably, when the first 100 units are released, 50 customers on the first day succeed to break the software. Unfortunately there seems to be no simple answer for this. It seems that there is an inter-relationship between the spiraling software complexity driving the hardware to ever increasingly complex chips, which in turn invite more software complexity. The sad truth is that there is not a single person who understands the entire software system any more on today's systems. So how can you establish the integrity of such systems? With old computers like the COSMAC 1802 we could do all that needed to be done with a small fraction of the complexity that is routinely used today for much simpler functions. Use the KISS principle instead of "creeping features". Here is another example: >LOS ANGELES (AP) -- The main computer has shut down on the $1.3 billion >NASA satellite launched last week, though officials said Thursday that >it would continue orbiting safely and a software change would fix the >problem. > >The Terra spacecraft, designed to collect global data on the Earth, had >earlier suffered a software glitch that delayed its scheduled Dec. 16 >launch until Saturday. > >And on Sunday, its high-gain antenna stopped automatically tracking >other NASA satellites it uses for communication. Controllers were able >to restore the tracking function. Why do they need a "software change to fix the problem" if they believe the problem (Single Event Upset?) was caused by the South Atlantic Anomaly??? Merry Christmas
...imageine the overclocking potential when you're running your chip at around -270C! Of course, the other half of the time it fries...
yep... that's right
The problem with the ARM processors is that they don't have an FPU. With floating point emulation, the StrongARM can be slower than a 486 because the 486 has a real FPU.
Some clarification: ISS (the US side, anyways) runs on 386 based computers (both the 12 MHz and 16 MHz varieties) built by Honeywell. There will be something on the order of 44 when the thing is finished, although only two are up there right now (and have been ticking along for over a year without a hiccup). The software is custom built by Boeing (mostly written in Ada). These computers are the ones in charge "running" Station. The laptops you refer to are actually the crew interface to these flight computers. They are Thinkpad 760EDs or 760XDs running Solaris. Everything you do through the main Space Station computers (like throw on the lights or change the attitude) is done through these laptops, which in turn connect to the main computers with 1553 data bus. There will be something like a dozen on board. When one goes down (which happens, I use them every day) grab another and reboot the first. There are also support computers that run Windows 95 to do non-critical stuff like write email and read procedures. They will connect with an NT equipped file server via an RF lan to share data. These computers are actually the same hardware as the ones mentioned above, they will just swap out hard drives to change from a command and control laptop running Solaris to a support computer running Windows.
You guys really think that NASA would use a comericaly avaliable OS on hubble or any other dedicated equiptment??? Cmon... They would make thier own Motherboard, Ram, BIOS, Software... EVERYTHING. Anything else is just too unreliable. MWP
FYI, i have seen some GE ultrasounds with 386SX CPU's on them. In fact, there are lots of medical devices that you pay over 100K and have a CPU too much inferior then your PC.
Gokhan Altinoren
I especially like your enhancement of my viewpoint. gene@viewtouch.com
The purpose for the three chips is for a RAID like system. With harddrives RAID is used to compare two harddrives responses with a third drives parity bit. the same system is used with the processors. This is done because of radiation having the effect of sometimes changing a 1 to a 0.
Well, lets see...two words can make my point: HEAT DISSIPATION If you want to try to keep a 450Mhz chip from burning up in a vacuum, be my guest... but its a whole lot harder than you realize... a 486 will is not too hard too cool and it works.("reliable, no new engineering... lets put it up!!!") This is only one of several reasons.
I never said that there doesn't need to be any local processing on the Hubble or that the Hubble doesn't need computer intelligence. I said that anything which does not need to be crunched up there should not be done up there. I said that the link is not less important than any other aspect of the system's automation. Why should there be a ~2to5 second latency? That's absurd. The control belongs on earth. The system up there has to only intelligently react. I've spent my life achieving what people like you say can't be done. Come back in ten years when you've learned a little humility.
Do you KNOW what they are upgrading from!? It was a RadioShack TANDY 1000TX up there!!! Why? Cause the darn things NEVER DIE! Even at -1 bizzilion degrees, well you get the picture.
What is it about pointy haired boss program managers choosing x86 processors for space applications? They expect to run windoz? Or maybe NASA can only afford development systems from garage sales these days.
Two of the hardest things to do in a spacecraft is obtain electricity and dissipate heat. A 486 consumes at least several watts. You can get roughly the same level of performance as a 486 using an ARM7TDMI MPU using nearly two orders of magnitude less power (and have smaller code size to boot - the T stands for Thumb code compression) If NASA has a buy US policy then check out IBM's 40X series of PowerPC embedded control cores.
And the Pentium? There's a huge f**king waste of silicon area and Amps for an embedded control application that doesn't need to be x86 compatible. Every heard of StrongARM? the MIPS R5270?, the PowerPC 603e? Are these guys idiots or is Intel paying them to use Pentium. I can hardly wait for the next Mars probe to be lost from a divide error or F00F bug. Anyone ever check that the state machines in the Pentium's complex instruction decoder are fully recoverable from single event upset error ("bush behavior" encoded).
They really shouldn't be doing much computing up there at all. The emphasis in cost and design should be on the most reliable speed of light link between the Hubble and all the computing power on earth. The computers down here should be doing everything possible. The computing up there on board the Hubble should be doing nothing more than necessary. There are no users up there. The Hubble is nothing more than the most sophisticated sensor that has ever been produced. It should be nothing more than a remotely controlled sensor. All the emphasis should be on the link between the Hubble and the control points on earth.
The last one I recall was a 50MHz 486dx2. Big heat sink but no fan required.
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To me, excessive cooling requirements for a CPU is a sign of bad design.
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This is why I avoid the latest CPUs. I suspect they're just slower CPUs that are overclocked. The ones that pass the performance test are relabeled as being faster CPUs. The ones that became unstable are sold as lower speed CPUs. Notice hou much cooler cheap $60 400MHz AMD K6-2s run compared to the first 200MHz CPUs? I still run a 200MHz p55MMX Intel and that sucker runs HOT. The aforementioned 400MHz chip's heat sink is merely warm to the touch. Touching the heat simk on the 200MHz chip will leave lines on your finger. I'll wager that the 700 and 800 MHz chips being produced 2 or 3 years from now will run much cooler. Why? Because by then the design will be FIXED unlike what we see now, which was rushed to the market on the advice of marketers... not engineers.
I work in the industry, specifically on flight software systems. We typically have to use old technology because ITS BEEN MADE RADIATION HARD. We use 300Mhz PowerPC's for early development in the labs, and because they happed to be a superset of the instruction set we use on the "state of the art" flight processor, the RAD6000 from Lockheed Martin Federal Systems. This is the processer that flew on the mars pathfinder missions. It has a dynamically selectable clock speed (meaning we ca jump from 2.5 to 33 Mhz just by writing to a register). It's a 64 bit piplined RISC processor, essentially what IBM was putting in AIX workstations 6 or 8 years ago, except now it's rad hard. They cost something like $300K, but if you need the fault protection (like memory that automagically corrects for single and multi-bit radiation errors, etc) they you have to start forking over the bucks. There's some movement in the industry into rad-tolerent (not hardened) PowerPC voting systems, but if your project is not in just the right orbit (or it goes to deep space) you need to be RAD-HARD. So it's not typically budgets, etc that drive things like processor choice. It's what technology will survive the radiation, thermal cycles, vib, shocks, etc. The typical PC motherboard wouldn't last 10 hours in most projects from the thermal cycle alone. A lot of student spacecraft projects fly PC's, 6811/12, etc. If you wrap enough stuff around them, they will work reasonably well most of the time, but you will be rebooting, watchdog resetting A LOT. Thats unacceptable for a probe doing nav calculations (unless you already screwed up your unit conversion, and then your screwed anyway!). The sad thing, is at 20Mhz, with really tight code, pipelining, and no cache misses, we might get 20 MIPS out of the RAD6K. LMFS is devloping a new higher speed PowerPC based unit, but I think it's still a ways out. Telescopes, etc didn't used to need much horsepower, since they were just sending telemetry, taking a picture or two, and wiggling some mirrors or doors. Nowadays, you have to do all sorts of analysis, correlation, and compression on the data before you send it down because the speed of the network pipe is the limiting reagent.
Acutally there are. You need to look in industrial computer catalogs. Considerable number of (expensive) parts for situations like this, including solid-state disks.
...phil
...phil
"For a list of the ways which technology has failed to improve our quality of life, press 3."
Those 1000 pins are in high-density cable connectors. The computers are mounted in sealed boxes.
...phil
...phil
"For a list of the ways which technology has failed to improve our quality of life, press 3."
Saw a news article about it a couple of days ago, but can't find the article anymore. (anyone?)
Anyway could be using this technology - works a bit like RAID only for whole computers rather than just disks.
Yes I know its been done before, but theres a twist -if only I can find the damn article.
Martin
In addition to the radiation and reliability concerns, as we all know the newer chips are larger thermal loads. And unlike here on the ground, you can't use fans for cooling. ;-)
Another thing I wonder about is, are the more powerful chips really necessary, anyway? In none of the satellite designs I've been involved with has processor speed been a design driver or technical limitation. Mass, cost, and power are generally the design drivers (sometimes schedule). I would imagine that a chip optimized for low mass, power, and cost (like a 486) would trade off very well against more powerful chips, especially if it is also very reliable. ;-)
:-) Spacecraft manufacturers always use computer architectures specifically suited to space use. They tend to have a lot of unusual devices to connect to the processors, sometimes more cards than a typical motherboard handles. As well, they're driven by the shake, rattle, and roll of launch, and the need to keep mass, power, and cooling requirements to a minimum.
The attention to detail that goes into the design of a spacecraft's computer architecture is pretty amazing, too, especially given that often the computer architecture is only used (as designed) once. And all too often, we're faced with integrating things designed for multiple different architectures (imagine getting a PC modem, SGI video card, and Sun monitor integrated into a Mac chassis.)
Failures occur, or more bluntly, sh*t happens.
There are two ways to deal with failures: Work to prevent them, or accomodate(and recognize) their presence.
NASA generally chooses to use failure prevention(via "hardening" engeering that adds voting circuits, for example) until it can get a high enough success rate such that the rare failed computations are an acceptable cost in the face of a vast majority of successful operations.
One thing to think about is that, in general, the Hubble itself is not the device that requires ridiculous amounts of computational power. It's far cheaper to have your supercomputers terrestrially based than to launch them twenty thousand miles in the sky! The Hubble is rather like the equivalent of a wireless VVVWAN passive sniffer / protocol converter, exchanging photons sent from distant lands into data which is then sent to the ground based equipment for rendering.
Do you demand that your network card have a Sixth Generation x86 chip? Same difference.
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
Wouldnt the LCD screen FREEZE? And palm Pilots cost alot more then a $0.50 used C=64. And they are easy to hack, both hardware and software.
I have to return some videotapes...
I worked on the Alexis Project at Los Alamos New Mexico in 1993/4. It was a X-ray telescope and used processors I thought were positively ancient for the time. However I found out that these were needed because the amount of times a reset occured because of X-ray, gamma-ray, highspeed particles is really scary in space. These particles have very small wavelengths but high energies and the smaller the circuit the more circuits that they are going to affect. This will cause anything from NO-OPS to hard damage of the circuit (which eventually causes the chip to be useless.)
I am pretty sure that the 4 486's are doing the same thing that the 6-8 gyroscopes are doing.. they all do the same thing but if they dont agree they do it over again to see if the second time they do. If multiples do agree the wrong one is marked bad and may be shut down depending on how many times it occurs.
The next generation chips that will need to be used in space are the ones that are both hardened and redundant. I think it was Motorola or IBM that had a chip that you could physically abuse and it would keep going due to the amount of redundancy in it. The problem is that it aint speedy :)
BTW, in case people think that this doesnt happen on earth. I also learned the hard way that above 1km you get more and more problems from radiation on chips. A lot of non-repeatable memory problems we had at Los Alamos got linked to high energy particle/waves coming in from space that usually get blocked by the atmosphere... I also remember reading a paper where similar things occur in buildings with large amount of granite (general decay of various elements) or other stones.
Stephen Smoogen (Physicist in Support clothing)
-- SJS smooge at smoogespace dot com
What is it with Slashdot's dweeping of Beowulf clusters? Noone seems to be able to mention "new computer" without Beowulf being mentioned by someone
The comedy pro technical term for it is 'running gag'. They've been used pretty successfully throughout comedy history, and every culture seems to have them. For example, North Carolina's had Jesse Helms as a running gag for decades now.. And I hear England's royal family continues to garner laughs after centuries, I guess that joke never gets tired...
Your Working Boy,
(Although each computer can have a network device, and be hooked up to a standalone drive system. That's possible, and makes more sense.)
How cool would that be to have "National Aeronautics and Space Administration" plus the NASA logo embedded in your computer's BIOS and displayed on boot! Killer.
-- Give him Head? Be a Beacon?
-- Give him Head? Be a Beacon? :P)
(If you can't figure out how to E-Mail me, Don't.
Given that the computer operating on a long-term spacecraft will have to withstand conditions (like -270 to +270 degrees Celsius with no heatsinks, heavy bombardment of all kinds of radiation from the "solar wind," etc.), it's small wonder why NASA only now has qualified the 486 CPU for space use. Designing the radiation shielding and thermal protection plus guaranteeing extreme reliability of use for years at a time requires a lot of engineering work, and frankly, it'll be some time before NASA will qualify a Pentium II, let alone a Pentium III, CPU for spacecraft use.
Raymond in Mountain View, CA
And having mutiple processors hooked up together dosent necessaraly mean SMP or any other kind of // processing you can think of. Given that it was ABC news, 'three linked computers' could mean anything.. It could be some kind of single computer with mutiprocessors (intel had supercomputers with hundreds of 8088's working together, after all) but this is a very specialized piece of hardware. The desiginers know that system FOO will peek at X cycles, BAR at Y, etc. FOO and BAZ use processor A, BAR and FRED use processor B, and C is held in reserve.
And they might only be 'linked' in the most basic sence - if the aiming system has its own computer (distinct from the others) they it would only have to communicate with the data aquisition computers with "stop collecting" and "start collecting"
This scheme is used in lots of situations where actual fault tolerance, not just high availability, is required. Here's a link to a company that makes Solaris servers that use this scheme:
http://www.resilience.com
Hard disks have cooling and reliability problems when used at high altitudes, such as at astronomical observatories in Chile. I don't think they would last long on a spacecraft.
Mea navis aericumbens anguillis abundat
There are two programs, PASS (primary avionics software system) and BFS (backup flight system). PASS runs on 4 computers and BFS runs on 1 computer. They were developed by two separate groups, IBM (PASS) and Rockwell (BFS). If PASS fails due to hardware or software problems, BFS can be used to fly the Shuttle.
Mea navis aericumbens anguillis abundat
Anonymous Coward is absolutely right. Is his score of "0" punishment for being anonymous, or spite over cutting through all the crap? There is NO reason for more computing power on-board the Hubble, just NASA's usual triple-redundant sets of simple systems. The network is the computer, guys -- remember? All the computing muscle is at JSC and JPL, where it belongs.
But it took five long screens of prattle about Beowulf clustering and space-based IP and 486 floating point calcs and NASA-branded BIOS and space-Kelvan overclocking to get to the point that the Hubble is just an appliance: in effect a scanner with the ability to point itself very precisely in three dimensions.
It's the world's biggest hot-synched Palm. It doesn't need Windows. It doesn't even need -- perish the thought -- Linux.
That makes me wonder if the computers are going to be "linked" and if so, how?
IIRC, there was talk of utilising the IP protocol we all know and love to communicate between 'craft' for want of a better expression. details can be found here. As it stands, far too many of my packets are routed to Mars for this to be a real innovation...
Triple redundancy is pretty much a standard for critical control systems; airliners, nuclear power plant, chemical refineries and so on. It is pretty well tested.
What is it with Slashdot's dweeping of Beowulf clusters? Noone seems to be able to mention "new computer" without Beowulf being mentioned by someone.
Could someone please explain what on earth Hubble needs a Beowulf cluster for? It's kind of pointless of drooling over a Beowulf cluster without having an idea what to use it for.
-- Abigail
The processors and drive have to be specially shielded and made to handle heat/cold extremes.
;)
Did anyone else think about how fast you could overclock your processor in space?
Last year, Intel pretty much gave the design of the Pentium to Sandia National Labs and NASA for ruggedization for use in space: Press release
http://dailynews.yahoo.com/h/nm/19991223/sc/space_ shuttle_46.html
If you read link above, you'll read following quote:
"'You have to keep in mind that we don't run Windows, we don't have disks, we don't do Internet,' John Campbell, project chief
for the Hubble, told reporters."
The reason for NASA and other agencies using the Intel designed chips is that Intel is giving them the designs of the chips to modify to the required specs royalty free.
The Sandia National Laboratory is currently preparing the Pentium for use in high radiation environments such as space, for more information check out the following sites
http://www.sandia.gov/media/rhp.htm
http://www.sandia.gov/LabN ews/LN12-18-98/intel_story.htm
Newer processors have increasingly smaller distances between the pathways on the surface of the chip. Since this distance is smaller, radiation can cause the electrical charge to "jump" across.
Not quite. Ionizing radiation induces carrier pairs in the silicon, possibly causing conduction when it shouldn't happen. Charged particles (esp. alpha) actually deposit charge where it can cause trouble. The most susceptible circuits are memories; dynamic memories actually store data in charge states, and static memories are intentionally very low-energy. Newer processes use smaller features and lower supply voltages, which reduces the charge needed to change state.
Unfortunately, for speed/power reasons all leading-edge processors use dynamic logic (similar to dynamic memory, except that the charges can be even smaller since the storage time is so much less.)
There are ways to minimize these effects with shielding,
Shielding is actually worse than useless, since cosmic rays are too penetrating to block effectively, but they do kick out secondary radiation from the shielding.
I'd love to know whether they're using the original Intel 486 or one of the newer 486 replacements that use static logic (which is handy in really-low-power systems since it lets you start and stop the clock at any time.)
Lacking <sarcasm> tags,
I'd had to say that such a comment is a little off-base, given that Pathfinder used a PowerPC-based architecture. I was lucky enough to take a "special topics in engineering" course here at Caltech with all of the folks that were on the Pathfinder project - a great group of bright, driven folks.
Joseph R. Kiniry
http://www.cs.caltech.edu/~kiniry/
California Institute of Technology
Joseph R. Kiniry
http://kind.ucd.ie/~kiniry/
Lecturer
UCD School of Computer Science and Informatics
Three computers? And if they disagree, the decision is made by majority rule? Ooh, if I worked in NASA, it'd be so hard not to refer to them as Melchior, Casper, and Balthazar...teehee...
--
"HORSE."
"HORSE."
-Flaming Carrot
Well, even if they weren't as vulerable (I of course have no idea whether they are ore not) they can't be used because they haven't been tested. (They're just too new to be used yet) Given the reliability required for these operations the NASA has to make sure that it will work, otherwise it'll get expensive ;)
There's (mainly) two issues as to the WHY:
- ----
1. A time tested system (one that has proven itself over several years of "real world" as well as experimental development use) is a more acceptable one to them. Thy don't want to send a device into space and six months later have it fail because of a processor bug that know one knew about.
2. As the circuits on computer chips get smaller and smaller, there is a concern over the ability for solar radiation to trigger (or disable) the circuit's switches.
--------------------------------------
Harris Semiconductor has spent a lot of time and effort making the iAPx86 processor line radiation hardened. And it works. But it doesn't work nearly as well for the newer generation as the older.
The tighter dies are more sensitive to charged particle events (Single Event Upsets, 'SEUs'), and the thinner nature of deposition makes the hardware more prone to heavy particle (permanent) events.
Older CMOS processors and memory were less prone to both types of error because of line thickness and spacing, depth of deposition and because of the voltage levels used.
The COSMAC 1802 is still a widely used space-borne processor!
Rad-hard planning is a non-trivial task, expecially when it's new to the designer. Trying to develop a design for a medium-altitude satellite was a challenge that a group I was once involved with was never able to satisfactorily overcome, and we lost the project because of it.
Having watched the evolution of the Shuttle system General Purpose Computers (GPCs) migrate from IBM proprietary processors to 80186s was a painful process. The software was clean-roomed, and 2 seperate groups of people developed code with identical functionality, while a 3rd group was responsible for testing. None of the groups was supposed to interact at all, and to the best of my knowledge, didn't even talk over beer... I suspect the Hubble ports are similar, although the rules for Manned Spaceflight code are more stringent.
Never ascribe to malice that which can adequately be explained by tenure.
Hmmz :) i like this... my home PC kicks way more ass than the hubble in CPU and Disk size:)
mvg,
Kris "dJOEK" Vandecruys
Exercise caution when modding this message up: the author acts like a jerk when his karma is excellent.
The DX-200 line of (mobile) phone switching centers uses a highly rendundant, highly scalable architecture using i486 processors. I don't exactly know where they get them, but I know they are selling the DX-200 like hot cookies.
Sigged!
"You should keep in mind we don't do Windows, we don't have disks and we don't do Internet," Hubble program director John Campbell joked.
We don't do Internet
Well, there goes my chance in space. Unless I can get a powerful transmitter down here that will let me read Slashdot with about a 40 second delay. Oh well, can't be worse than my connetion now.
We don't have disks
Disks that are able to endure an incredible amount of G force and an incredible amount of cold/heat. Interesting.. no wonder why they are not feasible, my disks don't even last from home school.
With not even going to touch the Windows issues,
Matthew
_____________________________________
sortakinda.ca | canadian paraphrasing.
Ironically, this means that the shuttle is carrying up into space components for Hubble that are much more modern than it's own computer systems - which are amazingly old, for similar reasons of known reliablity.
I dont quite understand what makes a 486 more resistant to radiation. ;)
I'm not a science expert, but I'm sure the hubble doesn't need a horrible amount of CPU. Why don't they just use an AMD-k63 450mhz? Last I heard those were around 50$ and I'm sure even NASA can afford that
Tyler
Haven't done much in the way of network programming, have you? The interconnect is almost *always* slower than what can be done at the endpoints; hubble's downlink probably benefits a *lot* from doing compression and other processing onboard.
Besides, you can't control a sattelitte with ~2-5 second latency. Also, should the Hubble crash when their's an ion storm or other disturbasnce that breaks the communication with the base station? Think about it; something that expensive and that far away better have a high degree of autonomy...
That's exactly what chipmakers do: they design a chip and then ramp the frequency up until "she can't take much more 'o this." Then it's time to design a new core: more efficient, smaller die, something like that. Coppermine, anyone?
This is also the reason that a good old Celeron-300 is the hottest chip intel ever made. That's the highest that manufacturing technique could go. It's pretty high too, you can cook meat on that puppy!
I still think it's cool how after hours of operation, my PIII-500 is much cooler than the voodoo3 main chip.
Tetris rules.
I read a Sun blurb somewhere that the ISS runs all control systems off of two x86 pentium laptops, (primary & backup), and all the astronauts use laptops running windows.
-Nick
Who volunteers to go up there with a Mandrake disk and help those poor astronauts out.
Have GNU . . . Will Travel
The drive is a hunk of RAM (or something not so volitile because
1.)No moving parts. (A service mission costs a couple of million per trip)
2.)Any spinning object (like a HD spindle) would impart rotational inertia on the satelite as a whole, and throw you off of the star you were trying to look at.
-Nick(my 4 canadian cents)
Have GNU . . . Will Travel
Solaris network on the space station.
-Nick
Have GNU . . . Will Travel
P.S. - How can the Shuttle astronauts use their pentium portables?
In comment to a couple replies asking why such old technology is used... If I remember correctly it has to do with how radiation can effect the state of the processor and chipsets. Newer processors have increasingly smaller distances between the pathways on the surface of the chip. Since this distance is smaller, radiation can cause the electrical charge to "jump" across. There are ways to minimize these effects with shielding, but as far as I know this is an "add on" that is not done by the chip manufacturers themself. I guess this would create a lead time.. IE: A new P3 chip needs x months of work to have a good shielding design developed, x months to test that... Coupled with the fact that this hardware is designed years before launch and you can see how things can slip. Remember also that comparing your desktop to something in orbit that was designed 20 years ago for a specific task isn't as easy as it might appear...Until recently NASA custom designed it's hardware and software. So, the Hubble running at 25 Mhz using all custom hardware and software is going to be a lot more efficient than a 25 Mhz 486 running Windows since it's all task oriented. I'm no expert of course, but I haven't seen some of our resident Super-Technical Answer Dudes (tm) post anything yet. (Probably still working on the formulas for their posts hehe). Case
Another reason for using old technology in space is that there is so long between the design of a project, and its approval and funding.
When the money finally comes, nobody wants to redesign the whole project.
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The ~3k avg temp in space would be ideal for overclocking!
I wonder if there has been any attempts at quake in space...Call up the Grays and lets have a lan party!!
NightHawk
Back in the day... When I worked at Bell Labs and went to Rutgers University, I knew a guy by the name of Dr. Dan Shanefield (http://www.rci.rutgers.edu/~mjohnm/shanefield.htm l). He has patents on a bunch of the chips used in telecom equipment back in the late 70s and early 80s. He taught a course in 'Electronic Ceramics' that many EEs and CerEs took. He explained the lag in chip use in satelite applications is because newer chips tend to be made of plastics and composites. This makes them cheaper for consumer use and does not affect their properties for normal use, but the radiation and temp gradients of space will destroy chips like that. The older 486 chips are ceramic-metal composites and can withstand some serious temp gradients.
The other factor is that the chips (and sometimes the whole solid state component) are coated with a thin layer of diamond. This increases its resistance to radiation, and EMP (electro magnetic pulse) in particular. A great deal of the NASA engineering specs are based on mil-spec so they must be able to withstand attack by EM weapons. Military satellites are supposed to be able to operate after a radiation burst as powerful as a nuclear explosion.
IMHO, I'm just glad to see that NASA is using off the shelf (inexpensive) components rather than custom designed stuff.
Ummm, Jon, aren't you supposed to be dead...? - Otter(3800)
Their are two problems associated with radiation, Firs are high energy particles which will over time blow through the silicon chip damaging it. And the other is charged particles depositing charges on the chip. As charges build up on the chip in areas it can cause bits to flip at pretty much random. the higher end processors of today are much much more susceptible to this because they have smaller etchings and hence a smaller charge can cause a bit flip. and as we all know random bit flips are BAD BAD BAD. But they institute other procedures for this. (like having all gates in triplicate then feed them to a voting circuit).
The processor linking that the refered to in the article will be NASA's normal triple redundant system.
All 3 CPU's do the processing and if one of them is different that one is deemed faulty and dropped off line. This system is also used with in the shuttle, although they have a 4th CPU due to the value and vunerability of the shuttles cargo.
How this triple redundancy works in actual practice is a question for some one else to answer.
A lot of posters are saying the previous computer was i386 based. I didn't design or build it, but the NASA page states that the previous computer was designed in the late 1970s and was it was difficult and expensive to maintain the original software. It does have a i386-based coprocessor that was added at a later date.
The press release states that the new computer allows the use of a more modern programming language. Presumably, they are using something like VxWorks for the OS?
Does anyone recognize the name of the old computer mentioned on the link, or know anymore details about the old (or new) computer? I wish NASA would be more open with details -- the average slashdotter knows more about his mobo than NASA is telling us about the hubble's brains!
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(I know this is a bit late in the thread, but...) .5 MB RAM a piece. The new 486's have 2 MB RAM a piece. Also, I think the new processors were all together in one assembly because a MSNBC article says there were approx 1000 pins in the unit they had to connect.
The old processors were 386's with
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