A couple, actually! Our solution is substrate based, which means that we can use some clever planting methods to grow multiple types of food in the same area – more variety is good for the palate. We also can grow root-based crops (which are comparatively high in calories) with much less fuss than a hydroponics or aeroponics system. Because ours is entirely based on plants, human waste from the astronauts can also possibly be composted to “refresh” the system so to speak. Note that I'm only bringing this up because this was a question that NASA asked us, and in no way am I saying that the astronauts can or should use one of these as a toilet. Composting waste should only be done safely and responsibly.

Our solution is also surprisingly light. I’m not a big person (5’2, doesn’t lift weights), but I can move our 2 foot by 2 foot around alone with a fully saturated substrate. I can’t remember what the weigh in was for our second plant, but I fully expect that a couple of astronauts in decent physical condition can move even a fully planted unit around. Not that they have to move the whole thing around – it breaks down easily.

Also, extremely low water consumption! It’s surprisingly lower than we originally expected. As mentioned before, to restore our 2 foot by 2 foot unit after a 35 day cycle and 2 months sitting unplanted and open, we added 1.5 gallons. That was an overestimation of the water that the system needed.