In article ,
Michael Turner writes:
To repeat: greenhouses on the Martian surface will get exactly one
benefit from being on the surface: direct daytime pass-through of
sunlight at frequencies useful for photosynthesis. That's IT.

That seems to be quite a significant advantage, not a minor one. How
do you propose to illuminate your greenhouses if not by direct
sunlight? You need either something like 10 MW/hectare if you do it
with efficient electric lighting or a collector on the surface at
least as big in area as your greenhouse plus at least a square meter
of light pipe per hectare if you do it that way.

Heat loss of a surface greenhouse won't be trivial, but it's only
about 30 kW/hectare even if the greenhouse is a perfect emitter.
Probably a factor of 10 improvement is possible by using low-e
coatings, depending on how much trouble it is to keep dust off them.

--
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA