Could spaceships just put a bunch of plants on board to produce all their oxygen and get rid of the carbon dioxide?
In: Biology
Yes, if you think about strictly in terms of chemistry. But developing a functional ecosystem is a lot harder than you’d think, especially on a spaceship with limited space. And if you have to intervene a lot to make it work, then research benefits aside, a plant-based system is probably not the most cost-effective.
Well if you mean recycle CO2 into Oxygen, then yes. The problem is that the main issues for Spaceships are weight and space (designing for more space means adding weight), because for every pound you launch, you also need some amount of weight in structure to support that pound, and some amount of fuel to propel that pound plus the structure, plus the extra fuel from Earth.
Plants aren’t very weight or space efficient. I’ve read that you’d need around 500 or so plants per person, and obviously you’d also need the energy for lighting the plants and watering the plants. In some future where we are building ships in space for very long space journeys, it may well make sense, for the foreseeable future though, they likely wouldn’t be used.
If they had enough light for the plants to photosynthesize, the plants could recycle the CO2 back into O2 yes, however there would need to be a substantial power supply to power the process which is difficult the further you get away from the Sun.
Seeing a lot here about the weight/cost/efficiently, which makes sense. But one thing that leaps to mine – we know that being in zero G affects animals (I recall a study on birds – they couldn’t feed on their own and had no reproductive urges).
Do we know how zero g/microgravity affects plant growth and metabolism?
in theory yes but that’s not the issue, if thy could that what they would od ot handle it, but having all thosep lants on board take up space and more importantly weight. it would quickly become economically unviable ot send a spaceship up with that cargo in good enough amonts to replace air recyclying systems.
Maybe if you use algae. Regular plants like grass/trees would weigh too much and inefficient.
This process requires light, and in that regard it’s pretty inefficient. Even assuming that 100% of light that you produce by some fixture is absorbed by the plants’ leaves. Most of that light simply heats the plant, and among that, a significant portion of the absorbed energy goes to running biochemical processes other than absorbing CO2 and producing oxygen and carbohydrates.
The other issue is that plants require massive amounts of water, which is another source of inefficiency. That water is evaporated from their leaves. In a spacecraft this can be recycled as condensation but this also consumes large amounts of energy.
Oxygen can be easily produced by running an electric current through water containing a small amount of acid as a catalyst.
This is vastly more efficient and much simpler than relying on plants.
Growing plants on spacecraft might be a useful activity for another reason, for producing food. But there are any number of other more serious technical issues with long term spaceflight that still open questions.
Yes, they could, but plants take a lot of space. They need dirt, fertilizer that contains minerals, a BUNCH of water (takes a lot of space on a spaceship) sunlight and space to grow. Spaceships usually don’t have that much place to waste, so it’s better for them to use compressed oxygen
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