Natural Science Forum / Earth Science / Mineralogy / September 2003

Larger!

This is going to sound flip, but write it on the wall of a cave.

Much of the cave art is at least that old--it was done with some simple
material which stains the rock (ground hematite/chalk/charcoal etc.)
and done in an inaccessible place with controlled temperature and
humidity conditions, to minimize weathering.

Now exactly how you are going to paint emulsion on a cave wall, and what
it should consist of, and how to expose it--well, that's up to you.
Maybe stencil it with a screenprint technique...

Survival time as such is not the issue.  A frankfurter lasts 50+ years
in a landfill (dated by proximate newspapers).  Under what
conditions?  What optical resolution?  Photoetched nickel and such
will pretty much last forever short of corrosion and abrasion.  Ditto
photoetched glass and moisture.  Photoresist on a silcon wafer,
expose, and etch.  It's good forever short of fire, hydroxide, or
dropping it.

How long did the Rosetta Stone last?  Pictures on gravestones?  Do
offset or silkscreen of pigments or noble metal precursor onto
ceramic, fire, then glaze.  You can do ink jet printing of ceramic
cups and slabs now - that gives you hi-res color.  While it is
invulnerable, you need considerable infrastructure.

Make a B&W photo and cast inside a thck slab of polyester resin or
PMMA.  Good for thousands of years.  Platinum tone it and cast in
plastic is better. Add 0.1% Tinuvin 327 (pale yellow) or Tinuvin 328
(colorless)to the resin for UV resistance, but keep it out of sunlight
anyway to avoid degrading the resin.

If all you want is a time capsule, B&W photo (preferably platinum
toned; well-washed with distilled water) loosely rolled, inserted, and
pumped own hard in a heavy wall Pyrex vacuum tube or ampoule to remove
10% moisture in the paper, then properly flamed shut with a bishop's
miter seal.  That should last the age of the universe if you keep it
out of sunlight - so give it wrap of several layers of aluminum foil
or electrolessly plate nickel.  If you are really paranoid, put the
sealed ampoule in an inch-thick wall Alloy C-2000 Ni-Cr-Mo (Haynes)
screw top high pressure bomb (with internal padding).  

1.  Etch into the surface of a durable and stable material (nickel,
stainless steel etc)

2.  Make a sandwich of it, with the image to the inside.

3.  Put it in orbit.

Eric Stevens

Black and white is easy to describe if hard to do.  Etch it on glass or
something.  Color is hard because dyes tend to degrade over time,
especially when exposed to light, and it may be hard to get good color
rendering with whatever you can find that's stable for as long as you want
it to be, although you could always etch three slides and combine red,
green, and blue light on a screen.

I think most newspaper columnists have photos reproduced that were taken
sometime during the end of the Pleistocene. If it is just the image you are
trying to preserve, you could  simply point a slide projector out into space
and focus the image onto a screen 5000 light years away. (keeping to your
analog only restriction). Will Estavillo