3 ms·
Plant roots don’t need gravity to draw water! Plants use evaporation and the tensile strength of water (yes, really!) to draw water up against gravity.
by jiggawatts 2y ago
Plant roots don’t need gravity to draw water! Plants use evaporation and the tensile strength of water (yes, really!) to draw water up against gravity.
- adrian_b 2y agoWhile that is true, plant roots and stems use gravity to know in which direction to grow (roots down and stems up), so that will cause problems in space. NASA has succeeded to grow some plants on the ISS, by making them grow towards a source of light (i.e. LEDs), but until now this has worked only for some very low-growing plants, like lettuce and some varieties of cabbage, not for plants with deep roots and high stems. It should be much easier to grow algae in the absence of gravity, but those are not as tasty as terrestrial plants.
- datavirtue 2y agoYou could probably engineer some palatable food items with algea and mushrooms. I would put my money on fungus as a food source.
- s1artibartfast 2y agoI think you are thinking of capillary action, adhesion, and vacuum pressure. Water does not have tensile strength.
- mikewarot 2y agoWater is capable of sustaining pressures of -140 MegaPascal, or about -1400 atmospheres.[1] [1] https://www.nature.com/articles/nphys2475 https://www.nature.com/articles/nphys2475
- s1artibartfast 2y agoThat is still different than mechanical tension.
- mgsouth 2y agoIt's very odd to phrase it as "tensile strength", but capillary action is an expression of surface tension, which is the result of molecular cohesion--two (water) molecules resisting separation. In other words, strength under tension, with measurable stress and strain. With some squinting, you've got tensile strength with elastic deformation.
- s1artibartfast 2y agoI think you are right and that is what they are getting at, but it is more a property of the system, not thee material. It is hard to reconcile fluid flow of a liquid with tensile strength.