There is reason to believe there is water frozen in a crater on the south pole of the moon.<p>If this is commercially exploitable,  this could be cracked into hydrogen and oxygen or otherwise be used as fuel and&#x2F;or reaction mass,  so it would make a huge difference in the economics of going to Mars.<p>Another thing needed for long-range space travel is radiation shielding,  and this can be as simple as a few feet of soil -- something which can certainly be harvested from the moon.