Somewhat OT: Long term design
in [Design]
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From: Joel Koltner on 14 Jan 2010 19:19 "WangoTango" <Asgard24(a)mindspring.com> wrote in message news:MPG.25b96ab48fc5c5b698ae28(a)news.east.earthlink.net... > I've watched TV and not only do those guys instantly recognize > millennium old devices, they recognize millennium old ALIEN devices, and > they all invariably function. I've always been most impressed with how readily humans seem to be able to pick up on how to run, e.g., an entire alien spacecraft despite said aliens not speaking any known language, not necessarily resembling human physiologically (e.g., the wavelengths you use in displays is going to be tuned to the individual species), and of course so often coming from planets with gravities and atmospheres highly compatible with human life. :-)
From: Phil Hobbs on 14 Jan 2010 20:09 On 1/14/2010 12:58 AM, Joerg wrote: > John Larkin wrote: >> On Thu, 14 Jan 2010 15:51:25 +1100, Sylvia Else >> <sylvia(a)not.at.this.address> wrote: >> >>> Joerg wrote: >>>> John Larkin wrote: >>>>> On Thu, 14 Jan 2010 13:31:08 +1100, Sylvia Else >>>>> <sylvia(a)not.at.this.address> wrote: >>>>> >>>>>> A recent episode of Stargate Atlantis prompted me to think about >>>>>> how would could design equipment that's intended to function far >>>>>> into the future. The episode required stuff to function 48,000 >>>>>> years after construction, but perhaps we could be less optimistic. >>>>>> >>>>>> Say 1000 years. >>>>>> >>>>>> Note, the requirement is not that the equipment function *for* >>>>>> 1000 years, but that when it is turned on, 1000 years from now, >>>>>> that it will work. >>>>>> >>>>>> It seems to me that semiconductors are out due to effects of >>>>>> difusion and radiation. >>>>>> >>>>>> But how about thermionic valves? They're not very reliable, but do >>>>>> they age when not in use? Would they hold a vacuum over that time? >>>>>> >>>>>> Obviously electrolytic capacitors are a no-no, but can resistors >>>>>> and capacitors be made stable enough that they'd work? >>>>>> >>>>>> Would it help to enclose the entire circuit in a vacuum tube? >>>>>> Again, could the tube sustain the vacuum over such a period? >>>>>> >>>>>> An energy source is a problem. Perhaps a cell where acid is added >>>>>> (how?) at the appropriate time? >>>>>> >>>>>> Sylvia. >>>>> I'd expect that most semiconductors and passives would last 1000 >>>>> years, given a conservative design. There's not much radiation around >>>>> at sea level. The gadget could be stored in vacuum or dry nitrogen to >>>>> prevent corrosion and wiskers and such. >>>>> >>>>> It shouldn't be hard to keep a vacuum tight for 1000 years. A decent >>>>> flange-sealed vacuum vessel hardly leaks at all. If it can do 1e-12 >>>>> torr for a minute, it leaks to atmosphere in (linear extrapolation) 2 >>>>> billion years. >>>>> >>>>> I think solar cells would stand up well. I bet that a Casio solar >>>>> calculator will work 1000 years from now if properly stored. The >>>>> biggest hazard would probably be polymerization of the plastics in the >>>>> keypad, or maybe leakage from a poorly sealed LCD. >>>>> >>>>> I still use my original HP35 calculator, purchased in 1972. >>>>> >>>> HP11C over here. I still use my grandpa's drill from around the >>>> 1920's. Works fine. You just have to keep the grease reservoirs >>>> packed by tightening the caps once in a while and refilling when at >>>> the peg. >>>> >>>> Oh, and the church we were married at goes back about 1200 years, >>>> the organ in there is probably well past 500 years. I guess a pipe >>>> organ fulfills the definition of "equipment". It can be done. >>>> >>> Well, I'm not sure the organ qualifies, even if it reaches 1000 >>> years. Has it never been repaired? >>> >>> The requirement is that the equipment be built, be left untouched for >>> 1000 years, and then work. >>> >>> Sylvia. >> >> Reliability folks generally assign component failure rates in FITs, >> namely one failure per billion hours. Most passives have numbers near >> 1 FIT, and lots of semiconductors are in the single digits. >> So a 100-part gadget that uses average 1 FIT parts will have an MTBF >> of 1e7 hours, a bit over 1000 years. That assumes the parts have no >> wearout mechanism. In practise, field failure rates can be quite a bit >> better than specs like MIL-HBK-217 or Bellcore predict, ie better than >> 1 FIT average per part. >> > > In Europe the problem with much of the Roman stuff was that there were > usually 5-10 fierce wars over a period of 1000 years. That kind of puts > a crimp into the MTBF. > Your part of Europe was obviously quieter than most. ;) Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: Phil Hobbs on 14 Jan 2010 20:16 On 1/14/2010 10:40 AM, Tim Williams wrote: > "Bit Farmer"<bit.farmer(a)yahoo.com> wrote in message > news:mfKdnZOAz8yitNLWnZ2dnUVZ_h9i4p2d(a)giganews.com... >>> But how about thermionic valves? They're not very reliable, but do they >>> age when not in use? Would they hold a vacuum over that time? >> >> You just put them on the outside of the Space Ship. That way you would >> never lose the vacuum. > > Not quite -- interplanetary space is around 10^-6 torr IIRC, which is good > enough for crappy triodes, but you won't get a 6L6 working quite well enough > out there. There's also a mixture of gas and particles which would be > better removed with a getter than the electrodes. A solar powered diffusion > pump (wait, do diffusion pumps work without gravity?) would be a low > maintenance solution. > > Tim > Interplanetary space is around 10^-11 torr, according to the Hitchhiker's Guide to the Galaxy, I mean Wikipedia. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: Michael A. Terrell on 14 Jan 2010 20:32 Joel Koltner wrote: > > "WangoTango" <Asgard24(a)mindspring.com> wrote in message > news:MPG.25b96ab48fc5c5b698ae28(a)news.east.earthlink.net... > > I've watched TV and not only do those guys instantly recognize > > millennium old devices, they recognize millennium old ALIEN devices, and > > they all invariably function. > > I've always been most impressed with how readily humans seem to be able to > pick up on how to run, e.g., an entire alien spacecraft despite said aliens > not speaking any known language, not necessarily resembling human > physiologically (e.g., the wavelengths you use in displays is going to be > tuned to the individual species), and of course so often coming from planets > with gravities and atmospheres highly compatible with human life. :-) They don't have to. The cast all read their scripts, and know what to do. ;-) -- Greed is the root of all eBay.
From: Sylvia Else on 14 Jan 2010 20:50
Michael A. Terrell wrote: > Joel Koltner wrote: >> "WangoTango" <Asgard24(a)mindspring.com> wrote in message >> news:MPG.25b96ab48fc5c5b698ae28(a)news.east.earthlink.net... >>> I've watched TV and not only do those guys instantly recognize >>> millennium old devices, they recognize millennium old ALIEN devices, and >>> they all invariably function. >> I've always been most impressed with how readily humans seem to be able to >> pick up on how to run, e.g., an entire alien spacecraft despite said aliens >> not speaking any known language, not necessarily resembling human >> physiologically (e.g., the wavelengths you use in displays is going to be >> tuned to the individual species), and of course so often coming from planets >> with gravities and atmospheres highly compatible with human life. :-) > > > They don't have to. The cast all read their scripts, and know what > to do. ;-) > > And the aliens in many cases not only speak English, but do so with an American accent. Sylvia. |