Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!nrl-cmf!cmcl2!brl-adm!umd5!uvaarpa!mcnc!decvax!decwrl!hplabs!hpda!hpcupt1!hpcuhb!hpscdd!spikes
From: spikes@hpscdd.HP.COM (Bill Spikes)
Newsgroups: sci.electronics
Subject: Re: electronic time capsule
Message-ID: <5770001@hpscdd.HP.COM>
Date: 26 Feb 88 18:51:19 GMT
References: <3a7af473.44e6@apollo.uucp>
Organization: HP, Santa Clara, CA
Lines: 57


Hi,
    Your time capsule problem is a good puzzle. It sounds like you have 
the electronics worked out. How is the oscillator going to fire up? Is
it going to have a capacitor or a crystal? What are the shelf lives of these?
    My input to the problem of the 200 year timer and protection of the
device is thus: Why not put it a few feet above the floor of the ocean in
a fairly deep spot? Probably nobody will find it, there is practically no
radiation, either man made or natural that will "age" the electronics, and
that is the last area man will be able to pollute.
    Now for the turn-on timer. The capsule is a fully sealed unit, antenna
included, weighted at the non-antenna end, filled with a non-corrosive
inert gas. It has photocells embedded in it on it's top surfaces for power
and in the bottom, a wave action generator (pendulum action, moving magnet
within coils) giving it two types of power. The capsule lives upside down
inside another container whose lower end is anchored to a weight via a cable
all made of the same indestructible materials as the capsule. The material
would probably be some kind of plastic, maybe the same type used to keep
Dick Clark from aging. The bottom end cap of the outer capsule has a seal
made of a substance that has a known corrosion resistance to salt water
and pollution products. I would think that boat, marina, and oil companies
would have much information on what the lifetimes of various materials
are in a ocean environment. You just pick one that will be mostly gone
in 200 or so years. There is no way to be super accurate about this as
man and Mom nature continue to change the environment, but I would bet that
our atmosphere will be in worse shape in 200 years than will the oceans.
    When the seal lets go, the top comes off of the outer container. The
weights in the bottom of both containers (until now on the "top" or surface
end) plus the "air" in the top of the capsule now turn the whole thing 
right side up. The inner capsule then slides out and heads for the surface.
The outer capsule has served its purpose. It kept the inner capsule dry,
and shielded it from what divers call "critters".
    You now have on the surface a clean, unweathered, and yet to be powered
up electronics package. If we haven't yet blown the earth out of orbit, the
sunlight hits the cells and hopefully the thing starts beeping. If there
is no sunlight, the wave action generator in the bottom of the capsule
provides power. This assumes, of course, that it's pivot has not fused itself
together.
    The best feature of the Ocean Release System (tm) is that the capsule is
now free to move around. This means that it has a better chance of finding
what is left of humanity. Also, even if the electronics don't function, it
still may wander past some type of intelligent life, that won't eat it, and
be opened. Although the scenario I have expressed here is somewhat fatalistic,
it is not unrealistic. Plan for the worst and hope for the best.
    If you are not sure of the oscillator starting after all this time, how
about letting wave action do the keying of the transmitter with the help
of something like a hall effect switch? It won't send perfect code but then
again, maybe it would stand out more in a cluttered frequency spectrum, 
especially if was annoying. :-)
    I would like to see some of the responses you have received and what 
the final design turns out to be like.


                                           Bill Spikes
                                           Hewlett Packard
                                           Santa Clara Division