Henry Spencer wrote:

In article ,
Dick Morris wrote:
The Mars Direct scenario uses only the Mars atmosphere for propellant
production, so it wouldn't be terribly difficult to test the prototype
hardware in a vacuum chamber with a simulated Mars atmosphere.

The biggest question is whether it will work with Mars dust in the air
it's pulling in. That's a little more difficult to simulate, since we
don't *know* the exact composition and characteristics of the dust.

Zubrin addressed the dust issue in TCFM, as I recall. His approach was
to liquify the CO2 under pressure and then purify it by distillation, so
that any dust in the air would remain in the solution. We don't know
the exact composition of the dust - presumably a mixture of silicates
with perhaps some salts - but the process suggested by Zubrin should
work with almost any dust composition. Atmospheric dust might be a
problem during one of the periodic dust storms, but it would be
advisable not to land during one of those in any event. It won't take
very long to react the initial seed hydrogen after landing, and we can
proceed at a more leisurely pace after that, shutting down the process
if a dust storm should occur.

It would be highly desirable to put at least a small-scale test of the
process on an earlier unmanned lander. (And that exact idea has been
proposed for other reasons.)

It would. The proposed Mars Sample Return mission would also give us
some fairly precise data on the kinds of atmospheric dust compositions
we could expect to occur.

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