Radiation effects sort of fall in three buckets: 1) gradual changes due to total dose - things like bias current or leakage current changes - ISS is in a low orbit and actually doesn’t see much dose; after all people live there. Maybe a Rad/year (0.01 gray). Opto isolators have problems with dose, but in general, in LEO, it’s a small effect.
2) non-destructive transient effects due to a high energy particle: solar protons and galactic cosmic rays for the most part - this is what causes “bit flips” for instance. You’ll see the term SEFI (Single Event Functional Interrupt) too - that’s where the processor or something locks up or spontaneously resets. Watchdogs and ECC are your friend. 3) destructive transient effects - This is the killer for most “consumer” equipment - something has a destructive latch up behavior triggered by the particle. Or the gate on a FET ruptures because the combination of the gate voltage plus the extra charge from the particle is just a bit too high. This is fairly common in switching power supplies, especially ones designed for cost - if you’re switching 120V, why buy 500V FETs. You’ll also get a “not so destructive but permanent” effect like a hot pixel in a imaging array. They fly a fair amount of consumer gear on ISS and a lot of it gets tested in various accelerator facilities around the country, and they come up with a predicted life. If the life is something like 6 months, and the experiment only runs for 3, then you’re good to go. They worry more about fire than radiation effects. James Lux, P.E. Task Manager, DHFR Space Testbed Jet Propulsion Laboratory 4800 Oak Grove Drive, MS 161-213 Pasadena CA 91109 +1(818)354-2075 +1(818)395-2714 (cell) From: Beowulf <beowulf-boun...@beowulf.org<mailto:beowulf-boun...@beowulf.org>> on behalf of Jeffrey Layton <layto...@gmail.com<mailto:layto...@gmail.com>> Date: Monday, August 14, 2017 at 10:12 AM To: John Hearns <hear...@googlemail.com<mailto:hear...@googlemail.com>> Cc: "beowulf@beowulf.org<mailto:beowulf@beowulf.org>" <beowulf@beowulf.org<mailto:beowulf@beowulf.org>> Subject: Re: [Beowulf] Supercomputing comes to the Daily Mail A friend of mine, Mark Fernandez, is the lead engineer on this project. He works for SGI (now HPE). They are putting two servers onto the ISS and are going to be running tests for a while. I don't know too many details except this. Oh! I do know they won't give you SSH access to the servers (already asked). I'm guessing they are gathering radiation impact on the memory of the system (cache and all), to see what happens. Probably check the health of the system too. Maybe when it comes back to Earth they will test it again and then pull it apart to look for changes. Jeff On Mon, Aug 14, 2017 at 4:30 AM, John Hearns via Beowulf <beowulf@beowulf.org<mailto:beowulf@beowulf.org>> wrote: The Daily Mail is (shall we say) a rather right-wing daily newspaper in the UK. It may give some flavour if I tell you that is most famous/infamous headline is "Hurrha for the Blackshirts" (1934) A surprisingly good article on using HPC and a visualisation wall to mode ocean currents. http://www.dailymail.co.uk/sciencetech/article-4775872/NASA-supercomputer-simulation-reveals-ocean-current-motion.html I would not delve into the Comments section though... I believe Mr T from the A Team is commenting here: "Learn physics fool. If you are the religious type then god created the laws of physics, so must be true; if not then the laws of physics describe what we observe so therefore must be true. Either way they are true. Learn them!" Hmmm.. .perhaps this person has a big future in HPC user support. "Its your bug, fool!" Read more: http://www.dailymail.co.uk/sciencetech/article-4775872/NASA-supercomputer-simulation-reveals-ocean-current-motion.html#ixzz4piTozmPo _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org<mailto:Beowulf@beowulf.org> sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
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