How to generate power on Mars? Solar panels are fine to
rove around a few kg of robot, but what about energy
intensive things: concentrating gases, shaping rocks for
construction, and the like? One remedy for scarce
resources is abundant power.
There is nothing to burn on Mars so it will
have to be
nuclear. There are those slow nuclear reactors like on
the
Soyuz but the output is nothing compared to a nuclear
steam turbine. Steam requires water and water is
precious
on Mars. Steam engines reclaim the water but water is
squirrelly and it is easy for it to escape.
I propose that a "steam" engine using mercury as the
working medium would be well suited for martian use.
Mercury offers the following advantages.
1. Vaporization at higher temperature. Cooling rate is
faster when temperature differences are greater. An
engine relying on phase change must get the working
fluid back to liquid. Higher temperature vaporization
means more rapid cooling / conversion back to liquid.
2. Very low volatility means less risk of atmospheric loss
from evaporation or sublimation; on Mars this would be
an important consideration when handling water.
3. Volume increase on phase change should be
comparable
to water.
4. Unlike water, mercury does not expand on freezing
and
so poses less risk of expansion-related damage to
machinery and containers.
5. Water has a propensity to dissolve salts, which then
corrode/ precipitate and otherwise damage machinery.
There might be airborne salts on Mars. Salts are
insoluble in mercury.
As a sidenote considering dust: I am thinking of the
cleaning power of water. Part of how it works is to
dissolve dust, but the kinetic interaction between fluid
molecules and loose contaminants (dust) is a big part of
cleaning. Fluid scrubs things.
Water used for cleaning is contaminated by the particles
it carries away. Mercury would offer the same kinetic
interaction and
stay clean, liberated dust particles floating to the
surface to be skimmed away.