On Wed, Dec 13, 2017 at 11:53 AM, Henry Vanderbilt
<hvanderbilt@xxxxxxxxxxxxxx> wrote:
Another less common (search "no.9 delay switch") involved a piece of lead
that had been fabricated in a way that produced a reliably repeatable
tendency to "creep" (slowly stretch and then break) under tension. Cut the
lead to a specific cross-section, then place it under a specific spring
tension, and it would break after a specific time ranging from minutes to
IIRC weeks, releasing the spring.
Someone looking at fail-safe deorbit mechanisms might find it useful to look
at what's gone before.
All of these methods are somewhat temperature dependent, and none (as far as
I know) are good for years rather than weeks, but the general class of
approach might still be useful. (Data from the old LDEF experiments might
well be worth looking at in this regard.)
One final thought: If such a process could be set up to be indefinitely
arrested by a small current (electrochemically?) it could result in a highly
reliable actuate-after-loss-of-power mechanism.
