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Electronics in space

Posted by: Techno311 - Fri Apr 04, 2008 7:38 pm
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Electronics in space 
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Post Electronics in space   Posted on: Fri Apr 04, 2008 7:38 pm
I wasn't sure whether this was the appropriate spot to ask this question, but since its related to technology I have a few questions.

I have read up on a lot of the prototypes and objects currently used in space. Whether they are satellites, the shuttle, ISS, etc. etc.

Here are some questions I have:
1. It seems that space rated electronics are really outdated. Is it me? if not, Why are they so outdated?

2. Assuming there is a gap, is it because technology needs extra durability to surive space? Does it have to go through certain tests before it can be used in space?

3. Is it a software related issue? Can we send up newer hardware without any reliability issues due to new software needed to run it?


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Post    Posted on: Fri Apr 04, 2008 11:14 pm
The most important reason is radiation. The finer the structures in for example microchips, the more vulnerable to radiation.

I remember when I think it was around 2002, Intel and NASA announced that they are making the Pentium (1) core radiation hardened. This was an enourmous multiplication of available computer power in space.

On Earth, Pentium 4s were available (or the AMD products with similar performance).

Additionally you need not only CPUs, but memory etc as well. This takes quite some time, costs money and has limits. I think I have a book here which describes the problems. I'll try to find it and tell you the title if you're interested.

And I'm sure some guys here working for satellite manufacturers can describe the problems a lot better.

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Post    Posted on: Fri Apr 04, 2008 11:21 pm
I suggest the detailed analysis of a Pro to really answer your question. Rick Fleeter in his book “The Logic of Microspaceâ€


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Post    Posted on: Sat Apr 05, 2008 12:30 am
If i wanted to learn more about the radiation aspect... would that book be the best source or does anyone know anything better?


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Post    Posted on: Mon Apr 07, 2008 4:14 pm
Keep in mind that the impact of radiation "Upsets" in semiconductor memories and processors can be significantly reduced by use of “Error Detection and Correctionâ€


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Post    Posted on: Wed Apr 09, 2008 10:49 am
Banks and such deal with these issues to and lock-step processing (two CPU's doing exactly the same thing and comparing notes) is common place.

On Earth cosmic radiation causes about 2 single bit faults in memory every month. The rate is just a lot higher in orbit, and higher again in deep space.

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Post    Posted on: Wed Apr 09, 2008 2:03 pm
idiom wrote:
On Earth cosmic radiation causes about 2 single bit faults in memory every month.
Two bit faults in how many bits total? One? Eight billion?


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Post    Posted on: Wed Apr 09, 2008 10:30 pm
Yeah well in a bank that bit might turn $10,000 into $90,000 or something.

Where accuracy is important minor amounts of radiation can be really bad.

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Last edited by idiom on Thu Apr 10, 2008 9:50 pm, edited 1 time in total.



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Post    Posted on: Thu Apr 10, 2008 9:50 am
I was being curious, not argumentative.


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Post    Posted on: Thu Apr 10, 2008 9:57 pm
Wikipedia has a pretty broad overview of current and past space applications for signal fidelity.

Wikipedias over view

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Post    Posted on: Wed May 28, 2008 3:02 am
Minthos wrote:
idiom wrote:
On Earth cosmic radiation causes about 2 single bit faults in memory every month.
Two bit faults in how many bits total? One? Eight billion?


RAM Error Correction Codes (ECC) are generally one correctable bit in 32, and multi-bit detection for the rest. This takes one byte for every longword - so you end up with a 5 byte longword.
The new BAE RAD-750 processor has more ECC bits than that, and can correct 2 bits and detect 3 or more, but I don't remember off hand how many correction bits it has...


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Post    Posted on: Sat Dec 06, 2008 6:30 pm
What about turning to light fibars and thus optical or light-based processing? I recently posted about news that seem to point there.



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