High Frontier can help Mars Direct

> The moon, in comparison, is an impoverished world. The moon is highly
> depleted in volatile substances. Many of the elements that are essential to
> human life, are almost entirely absent on the moon.

Well, absent isn't quite the right word. Very low concentrations in most
regions of the lunar surface (at least as sampled by Apollo and other
missions of the period). But Clementine and Lunar Prospector
gave us some reasonable evidence there's water in polar craters if not
elsewhere; there may also be ammonia and CO2 in those permanently
shadowed regions since projected temperatures are very low. Lunar
regolith does contain billions of years worth of trapped solar wind
gases, so there's hydrogen (and other volatiles) in ppm concentrations
down to several meters depth, all over the surface. There may be buried
volatiles in higher concentrations in some regions too, remnants of old
asteroids and comets.

> Many of the metals that are
> essential in modern industry, are extremely hard to come by on the moon.

Again, lower concentrations - the main one I'm aware of as a problem is
sodium. Which ones were you thinking of here? There's lots of silicon,
iron, aluminum, titanium, and magnesium at least. The "KREEP" deposits
have potassium and rare earth elements (and phosphorus). The
high-melting point metals are present in about the same concentrations
as on Earth's surface, if I remember correctly. But setting up a lunar
mining infrastructure is not likely to be easy, given the general
low-grade quality of "ores" we know about. One advantage is in the lack
of an oxidizing atmosphere, some metals are actually present in free,
un-oxidized form - it may be possible to extract iron dust without the
need for a smelter reduction process, for example.

One problem with Mars you didn't mention is, given the inverse square
law, incoming solar energy is much reduced...

Arthur (apsmith@...