FLASH! - New Report says plants love SPS, why not environmentalists

As for Mars, Mr.. Zubrin is just plane wrong if he says that, for the obvious reason that the moon offers a much better environment already, and is rather closer. Zubrin's argument was that on the moon the greenhouse windows have to be extraordinarily thick to screen out radiation, making lunar greenhouses uneconomical. For orbit, O'Neill recommended slag shields and arrays of mirrors to bounce light around them. Zubrin dismisses this possibility, saying that trying to buildmirrors on the same scale as your crop lands would get you into "preposterous engineering problems". What these problems are, exactly, he does not share with us. Even if there is no water on the Moon, there is plenty of solar energy, and water can be produced out of it. Mars may have water but has very little solar energy, so it's at least as bad as the moon AND it's a quintibazillion miles further away. Mars sucks, sorry. Oh, you're preaching the the choir here. Nothing makes me speak out more quickly than many space advocate's automatic assumption that it's easier (or better) to build habitats on Mars than anywhere else.