Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!decwrl!labrea!glacier!jbn
From: jbn@glacier.STANFORD.EDU (John B. Nagle)
Newsgroups: sci.electronics
Subject: Re: electronic time capsule
Message-ID: <17317@glacier.STANFORD.EDU>
Date: 19 Feb 88 05:18:04 GMT
References: <3a56593d.44e6@apollo.uucp> <615@jetsun.weitek.UUCP>
Reply-To: jbn@glacier.UUCP (John B. Nagle)
Organization: Stanford University
Lines: 18


      Timing is the easy part.  It's not at all clear that we have the
technology to make electronics with a shelf life of a century, let alone
an operating life that long.

      Capacitive-type EPROMS will probably discharge within a decade or
two.  Lifetimes of other components are more problematical.  Ceramic-packaged
militarized ICs might make it.  Electrolytic capacitors probably wouldn't.

      A good first step would be to build something that would survive
a year of 2-hour freeze/bake cycling.

      Whatever it is, it should have redundancy.  It would be useful to
have two units checking each other, and as soon as one failed, the 
other would go on the air, so it would make itself known rather than
being forgotten.

					John Nagle