On Jul 1, 10:36 am, (Steve Willner) wrote:
.... They seem to
be assuming a perfect emitter and a factor of 2.25 for the ratio of
radiating surface to greenhouse area. These strike me as very
conservative assumptions.

Perhaps they are trying to compensate somehow for their apparent
assumption of agriculture only in mid-summer?

Since you're going to need electricity for many other purposes anyway,
I like the idea of using LEDs in both lunar and martian
agriculture.

Notice that the electricity you have to supply to the LEDs, depending
on assumptions, is more than you would have to supply to heaters.
Take a look at Fig 9 in the Hublitz et al. paper.

Which shows not electricity specifically, but heat gain. And not from
LED illumination, but from incandescent lamps. Apples and oranges
comparison. What I thought we were now talking about is a system
where most heat is supplied separately from illumination. Fig. 9
suggests to me that you might as well separate the two functions. It
also suggests to me that, as long the simplest and most manageable
design is an opaque insulating shell over your plants, you might as
well simplify further and locate agriculture in a lava tube, not on
the surface. Solar storm particles would drill right through that
insulating layer and (probably) kill your plants, unless the shell is
covered with very thick pile of Martian regolith. Well, nature might
have prefabricated such shielding: cave ceilings. Why waste it?

-michael turner