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View Full Version : There's a G3 around Mars




Sdashiki
Mar 14, 2006, 10:02 AM
I had no idea that the G3 chip was just, like, so, like, awesome?

Lol.


Mars Reconnaissance Orbiter’s main computer is a 133 MHz, 10.4 million transistor, 32-bit, RAD750 processor. This processor is a radiation hardened version of a PowerPC 750 or G3 processor, with a specially built motherboard. The RAD750 is a successor to the RAD6000. This processor may seem underpowered in comparison to a modern PC or Mac processor but it is extremely reliable and resilient, and can function in solar flare ravaged deep space.

So I guess I am going to be taking a clamshell iBook (tangerine, of course) to Space.

source: Wikipedia (http://en.wikipedia.org/wiki/Mars_Reconnaissance_Orbiter)



Spanky Deluxe
Mar 14, 2006, 12:12 PM
That's soooo cool. One has to bear in mind as well that first of all the hardware for an extra-terrestrial satellite is worked upon for months and months, if not years and has to be perfect so they don't normally go around putting in the latest and greatest processors and secondly, it takes quite a while for something like that to get there. If you factor all that in then its not *that* 'slow' a chip. Also do you really think there are any better software coders and optimisers out there better than the guys from NASA/ESA or the like?!!

munkees
Mar 14, 2006, 12:49 PM
133 Mhz is not slow,

i remember running linux version 0.92 back in 92 on a 486SX25 with 4 MB ram, it want 8 for X windows, but it still ran it with 4 and was not slow. There is no slow GUI on this 133MHz G3 so it probably screems. I cannot see it doing much in the way of high intense processing. It life is probably managing sending and receiving data. Being the main processor, collecting info from the sub systems then beaming to NASA for processing.

I also remember back in 97 had dual Pentium Pro (2 CPU) running at 100Mhz, with 160MB ram, what a kick as system, smoke the Pentium II 600Mhz we had just got.

Remember if an OS is great it should not need more CPU with newer releases but few CPUs. I have put MAC OS X on an iBook G3 700, the faster version is 10.4.X tiger, Goes to show another good reason why I like Apple and Mac OS X.

It is running VxWorks, with I have many years of expierence programming with, We can run a 100 Base T router max out at 85 Mhz and still have CPU cycles left over, that with NAT, and firewall switched on. Though I think VxWorks is crap, I had to rewrite it network design so it did not put all the jobs on there stupid thread that. I created my own thread, and redid the system buffers, and it improved performance. Also VxWorks has a very buggy IP stack I had to rewrite wrapper around (they charge to much to get the source code). I this system rocks, It has 20GB of ram for storage, My guess that must fill up time to time, while it goes though black out periods with NASA

Tilmitt
Mar 15, 2006, 07:06 AM
I read somewhere on wikipedia that the PowerPC 604 (I think) which would be like a "G2" was used in two Mars missions...

FireArse
Mar 15, 2006, 07:16 AM
it has 20GB of ram for storage, My guess that must fill up time to time, while it goes though black out periods with NASA

I thought 32-bit architecture had a limit on RAM? was it 4GB?

F

Spanky Deluxe
Mar 15, 2006, 07:26 AM
I thought 32-bit architecture had a limit on RAM? was it 4GB?

F

While that is true chances are that huge amount of RAM was mostly set up in the form of a RAM drive similar to those PCI cards on which you can mount several dimms and then connect that to the SATA bus for an ultra fast RAM Drive. A similar tech could well have been used in this build. Mind you, pretty much everything would have been custom built and they probably simply used a custom memory controller or something, remember it is NASA.

Josias
Mar 15, 2006, 07:32 AM
I don't understand why there is no G1 or G2:confused: . PPC is a very well designed processor. Though Core Duo may be faster, it has many errors that the PPC didn't have. For example the divide by 0 error. Many iMac Core Duo users have had that experience. I have seen a 1.07 GHz G4 in action, and it is not slow as you would think.:cool:

GilGrissom
Mar 15, 2006, 07:33 AM
Pretty cool.

Someone told me something about another processor they used in some of the other space stuff they have floating around up there. They are all older processors, something to do with the size and spaces between the transistors I think. They can't simply put the fasted most advanced (in terms of the size of the transistors and how close they are together) in space stuff even if they wanted to, or something like that.

It's something like that, think one of my uni lectureres told me that...

combatcolin
Mar 15, 2006, 08:12 AM
Pretty cool.

Someone told me something about another processor they used in some of the other space stuff they have floating around up there. They are all older processors, something to do with the size and spaces between the transistors I think. They can't simply put the fasted most advanced (in terms of the size of the transistors and how close they are together) in space stuff even if they wanted to, or something like that.

It's something like that, think one of my uni lectureres told me that...

I have also read this before.

Becasue modern CPU's are so densly packed if any radiation ws to pass through them they would be toast, older chips are less dense and so more able to survive the intense radiation of space.

munkees
Mar 15, 2006, 09:47 AM
The first space shuttles use 5 8088/8086 hardend chips. Each cheap ran the same software at the same time, they were located in different parts of the shuttle. fail safe design.

mmmcheese
Mar 15, 2006, 10:37 AM
The first space shuttles use 5 8088/8086 hardend chips. Each cheap ran the same software at the same time, they were located in different parts of the shuttle. fail safe design.

They still do...a few years ago NASA was using ebay to find more 8088/8086 chips and 8" floppy discs because their stock of them was getting very depleted.

Some people wonder why they don't upgrade, but it simply comes down to that they don't need any more speed for the job they are doing, and if they did change, they would have to go through years of validation again. The science experiments on board are typically standard laptops though, so they are much quicker.

Kingsly
Mar 15, 2006, 11:17 AM
They still do...a few years ago NASA was using ebay to find more 8088/8086 chips and 8" floppy discs because their stock of them was getting very depleted.

Some people wonder why they don't upgrade, but it simply comes down to that they don't need any more speed for the job they are doing, and if they did change, they would have to go through years of validation again. The science experiments on board are typically standard laptops though, so they are much quicker.
On that note...
I read somewhere that the combined processing power of the Apollo capsule was that of a modern graphing calculator! :eek:
So... I am imagining a replacement space shuttle (the crew exploration vehicle) that runs on a quad G5 inside a hardened lead casing.
That would be cool.

munkees
Mar 15, 2006, 11:23 AM
There is a high altitude satalite is running G4 powerbooks, I remember the story on apple website

Kingsly
Mar 15, 2006, 11:36 AM
Yes, I seem to remember something about the ESA using macs in a satellite and the NASA sister satellite used a PC. Guess which one failed in flight.

Edit* maybe it was the other way around, with NASA using Macs... I don't remember.

mmmcheese
Mar 15, 2006, 12:09 PM
On that note...
I read somewhere that the combined processing power of the Apollo capsule was that of a modern graphing calculator! :eek:
So... I am imagining a replacement space shuttle (the crew exploration vehicle) that runs on a quad G5 inside a hardened lead casing.
That would be cool.

That said, the G5 would introduce a lot of weight, heat and power issues not present in the old processors. If they jobs they are doing run fast enough on the old processors, the extra costs associated with the G5 are wasted.

Cooling processors in space is very difficult, especially if they items are in a vacuum. Where does the heat go without wind currents? The answer is nowhere, and since you can't dissipate heat, the processor and/or heatsink just get very hot and are no longer effective.

Kingsly
Mar 15, 2006, 12:43 PM
That said, the G5 would introduce a lot of weight, heat and power issues not present in the old processors. If they jobs they are doing run fast enough on the old processors, the extra costs associated with the G5 are wasted.

Cooling processors in space is very difficult, especially if they items are in a vacuum. Where does the heat go without wind currents? The answer is nowhere, and since you can't dissipate heat, the processor and/or heatsink just get very hot and are no longer effective.
Yes but thats why you sink the processor core in liquid nitrogen (they do it here on earth to OC PC's)
Also, they DO have radiators in space. Some of the large "solar panels" on the ISS are actually radiators. Heat dissipation is about the transfer of energy, not wind.
Furthermore, Why cant the onboard computer be located within the main passenger cabin? Use G3's to power the outboard systems and report back to the main computer, the Quad G5. The Astronauts can also use Bonjour to interface w/ the shuttle via floating MBP's. :)

dr_lha
Mar 15, 2006, 05:00 PM
Cooling processors in space is very difficult, especially if they items are in a vacuum. Where does the heat go without wind currents? The answer is nowhere, and since you can't dissipate heat, the processor and/or heatsink just get very hot and are no longer effective.

There are two forms of heat transfer: Convection and Radiation. You're thinking of convection, which of course would not work in space. However radiation works, which is how satellites deal with heat in space, radiators are usually mounted on the sides of spacecraft, normally facing away from the Sun, so that heat can be radiated into space.

BTW - the satellite I work on uses a RAD6000 CPU, which is also a PPC core. These are very common in space use.

zap2
Mar 15, 2006, 05:02 PM
:eek:


And Jobs is switching us to intel, :D

dr_lha
Mar 15, 2006, 05:02 PM
Yes but thats why you sink the processor core in liquid nitrogen (they do it here on earth to OC PC's)

Yeah, doing that in space is incredibly difficult to do, and unnecessary. For one thing liquid Nitrogen evaporates, so once you run out the Spacecraft no longer works. Also the extra weight needed to carry a Nitrogen dewar into space is very expensive.

The only time you see Liquid Nitrogen used in satellites is for missions with detectors that are extremely sensitive to heat, for example IR missions or ones with superconducting detectors that only work at very low temperatures.

WildCowboy
Mar 15, 2006, 05:03 PM
I don't understand why there is no G1 or G2:confused:

While the "G1" and "G2" terms weren't actually used, they refer to the 601 and 603/604 chips, respectively.