Since perchlorate was covered below, one of the "moderators" took the opportunity to remove my explanation for it.

First off, one revenge I will have on those who did the electronic hacks on me several years back will be to watch them squirm for the rest of their lives as the population generally comes to realize that Mars is not Earth-like. I much enjoyed the perchlorate thread below. Great fun.

Now to matters at hand.

Mars' core has cooled; it has lacked a protective magnetosphere for a long time. Perhaps our Moon keeps Earth's core molten to some degree; another factor is size.

Perchlorate?: It appears ionizing radiation hit Mars' water, the hydrogen outgassed, and the oxygen combined. My assumption is that salt, when hit by ionizing radiation, converts into sodium and chloride; could the sodium outgas?

The chemistry is going to be bizarre, as Mars is not Earth-like.

Sagan thought that Mars was sterilized by hydrogen peroxide, but he was wrong, so we still have the back contamination problem to resolve.

As far as Mars' value goes, Eby used to handwave that the ioninzing radiation problem could be overcome by creating a shielding atmosphere; it would appear that he was wrong.

As far as the architect of Direct goes, I kind of like multiple people claiming it. Its kind of like anonymous and scientology; in this case the confusion will keep ATK guessing. Direct is a many, everywhere. They do not forgive; they do not forget, but they don't remember very well either.
The situation may be like "Vietnam with Sand", but in this case there was one identifiable first person who had the idea.

BTW, "moderator", sometimes Google archives habitable zone faster then you remove my posts.