suggested long ago,

that the entrance

and exits of underground

be covered by

 

these pillars...

 

kind of a flat version of

the biosphere...

 

but not quite aiming

for eco-diversity of the

biosphere,

 

but for food/oxygen,

and shielding from radiation....

 

 

all using natural resource

from Mars instead taking it

there.

 

then, as a second phase,

once resource/mining is located,

 

 

then slowly move out of that

underground habitat,

 

and live in the open,

shielded from radiation by

the buildings made almost

purely of metal.

 

and many structures....

 

CNC and welding is the way....

Fastest way to mine,

 

all in automation.

refined of steps of processing,

 

is the way...........

 

IMO.