On Tue, Oct 31, 2017 at 10:02:53PM -0400, Kurt Feltenberger wrote:
> Which leads me to wonder about what damage prolonged vacuum exposure might
> result.  What would weaken or fail, what would be ok, etc.  Granted, the
> materials science of the various empires, and Imperiums, probably found a
> solution, but what about the lower tech societies or if they didn't?

Even given lower tech societies, space travel in Traveller has been
common for longer than we've had writing.  The hard work of finding
out this sort of thing has been done, and even societies that have
only recently built their industrial base to the point of making
spacecraft would almost certainly have had such basic information
available beforehand.

Generally the biggest problem is outgassing.  Many "solid" materials
contain volatile compounds that will diffuse out and evaporate over
time.  For things like soft plastics or fabrics, the result is usually
more brittle.  The main solution is to use materials without such
volatile components.  However, interior furnishings would ordinarily
be expected to designed for atmosphere, and may suffer with prolonged
lack of air.

Any liquid will also evaporate eventually, even those with quite low
vapour pressures.  Even some (few) solids will sublime to gas over
time.  This includes many types of lubricants.  The solution is not to
use liquid lubricants (or solids that might sublime), or to ensure
that they are completely sealed.

Radiation can also cause damage.  There are many different forms, such
as cosmic radiation, stellar storms, and even a constant bath of UV
radiation without the benefit of atmospheric absorption can cause
significant damage to many materials.  Radiation shielding in
Traveller appears to be extremely good in normal operating
circumstances, but maybe part of that is due to some active systems
that won't be functioning while mothballed or derelict.

Vacuum cementing might also be a problem and it can worsen over time,
although not nearly so much as some writers make out.  Many
combinations of materials are hardly affected, and presumably those
would be used in Traveller.

Cyclic extremes of heat and cold may be a problem in some cases.
Thermal fatigue can affect a very wide range of materials when the
temperature might cycle hundreds of degrees, thousands of times.  Many
of the materials used would be designed to cope with such changes, but
in ordinary operation mostly just the hull would encounter them.

Derelict ships in an outer system might drop to 20 K or so, almost
certainly far below the temperature range for which most of the
materials and systems were designed, and hazardous to boarders in its
own right.  The hull is likely designed to handle such temperatures,
but the interior probably not.

If the ships were properly mothballed, they probably have precautions
taken against all of these in addition to routine use of materials
that lessen their effects.  Derelict ships may be in somewhat worse
condition though, in addition to damage from whatever it was that led
to their becoming derelict in the first place.

- Tim