hello everyone. i’m a design student who’s been given a weird exercise.
long story short, I need to know how would a living plant survive in outer space, hypothetically.
laugh as much as you want - but, say i have a growing seed, and i am currently on a space station. In what kind of vessel should i store it in order to release it outside?
I know a question like this cannot be taken seriously, but, i’ll take my chances- let your imagination run free
Well, the plant needs water, and it needs a pressure vessel. So the vessel has to be made of a material that can hold pressure. A plant may actually do just fine in a lower pressure environment than humans can survive in - it doesn’t have metabolic processes that need large amounts of energy all the time.
The minimum is that there has to be enough pressure that there is liquid water without it boiling.
Temperature is another issue. You need incoming heat to equal outgoing heat at an equilibrium temperature where water is liquid. What I mean is, if this vessel uses sunlight, the heat gain from absorbing sunlight must equal the blackbodyradiation of this vessel to space at say 300 kelvin.
You can treat your habitat like a very thin disk where one side faces the sun, and one does not. Look up the percentage of light reflected from typical plants across the entire EM spectrum. Select a target temperature. This will let you solve for how much total surface area needs to be on the “back side” of your disk. (some geometries have more surface area than others)
Ok, so pressure and temperature and sunlight. What about radiation exposure? Well, this can be fixed by careful plant selection. Some plants are constructed in such a way that radiation won’t hurt them as much as others. The ideal plant to use is algae because each single celled organism is a separate plant, and they are all competing with one another. This means that as radiation damages some of the algae, others will still have intact enough genes to keep reproducing. Sorta. Your pressure vessel might not be big enough.
The problem is, on the Earth, the magnetosphere blocks charged particles from the sun, and the atmosphere acts like a big shield that blocks gamma rays. A thin vessel in space doesn’t have that kind of protection. Realistically, though, it would be fine for a while.
Do you need circulation pumps to artificially move the water around and mix air in with the water if you are using algae? Maybe not. Obviously your greenhouse would run a lot longer if you had various systems that maintained all this. Thrusters that stop spin. Electric coolant pumps to control temperature. Air pumps, water, pumps, etc etc etc.
In theory, though, you could build a totally symmetric sphere made of a transparent material. (some kind of glass or plastic). If you made the sphere just the right size, the internal equilibrium temperature might be acceptable to plants. Maybe. Probably not, though - and any design where you have heat radiating or absorbing plates or something else to control temperature, you quickly arrive at a design where the orientation of the habitat matters. (certain angles and it gets too much sunlight heating, other angles there is too little)
Ideally, I feel like the answer you are looking for is a way to make a simple shape out of a strong form of glass or sapphire or plastic, and have some water and plants in it, and the plant lives in space for decades before finally dying from one failure or another.
Once you start adding orientation thrusters or gyroscopes, pumps, solar panels for power for, control electronics, radios, gas regulation systems, etc etc etc, it becomes enormously more complicated, heavier, and there are a lot more things that could fail.
So what’s the exact parameters? Are you asking what is the minimum amount of hardware you would need to keep a small houseplant alive for a few days outside the station?
Or do you want a way to keep plants alive for as long as the Earth has been around?
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Welcome to the SDMB, dazedd
We have a “no homework” rule here, which isn’t quite as strict as just the words “no homework” might imply. Basically, you are allowed to ask for help if you get stuck, as long as you show that you have put some effort into the problem, and you are asking for hints and explanations so that you can understand the problem and finish it yourself. You can’t ask us to do your work for you.
Since your post seems to indicate that you want us to answer the question for you, this would be in violation of that rule. I am therefore going to close this.
If your post is not in violation of this rule, send me a PM with an explanation and I will re-open the thread.
Thread closed.
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I received a PM with an explanation from the OP and am now convinced that they are not simply seeking the answer to a homework question.
Thread re-opened.
Habeed, first let me thank you for such a detailed reply.
I have to admit that I kind of lost you somewhere deeper into your explanation.
I guess I am indeed asking about the minimum amount of hardware needed. This project, eventually, has to be convincing, but since we are talking about designers - my professors included - neither of us being engineer/physicist, it should be just a very basic prototype. It also has to be as lightweight as possible. It is a crucial thing.
I’ve started my researched with this interesting product called “micro garden”, and they use Agar Agar gel for the plant’s base. I was hoping to use the same thing. Other than that, I have no direction as for correct shape, material, etc.
The absolute minimum that works for even a brief period of time is :
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Plants need pressure. This is because in the vacuum of space, water at room temperature will boil.
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Plants need light. You need either some LEDs lights suitable for plant growth on the inside of the pressure vessel, or the pressure vessel has to have transparent sections. The LED/solar panel on the outside is probably an easier solution to make work and fabricate a prototype.
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Plants wilt if it gets too hot, and they freeze if it’s too cold. This is why I had a brief explanation of the need for some kind of thermal regulation. This is probably the most difficult part of the project.
Here’s some interesting links if you haven’t already come across them:
Plants Grow Fine Without Gravity
Plants in space (sounds like the title of a cheap sci-fi movie but it’s actually a wikipedia page)
Plants in Space (from NASA - these guys tend to know a few things about space)
I’m not sure why you think this is a ridiculous question. If you google “zero gravity plant growth” you’ll see descriptions of experiments aboard the ISS and other space stations. Here is a Wikipedia article on the subject.
I thought it may sound ridiculous because this is a “concept” project in design school, and I am not an engineer who can actually manage to grow a plant in space.
The main issue is that everything I came across, including those link you two have provided me, is discussing plants inside a space shuttle rather than outside, literally in space.
Habeed, you are talking about pressure - could you elaborate? Could it work inside a sealed glass or is it something else? Does it require a certain shape?
I should also mention that the plant is a small sprout.
Plants require liquid water. In a vacuum, both the external water in the growth medium and the water in the plant cells would evaporate, and you would get a freeze-dried plant.
The OP has repeatedly mentioned growing “in space”. If we are talking about a weightless environment then there is one BIG problem to overcome first - plants seeds generally won’t sprout properly in a weightless environment.
A seed nestled in a nice dark layer of soil has no way to tell which way is up and which is down without a gravitational field. Net result is that the seed may start growing roots in and its shoot in the wrong directions. Only once the shoot breaks the soil surface does phototrophism take over.
Solution - make the planting bed rotate to simulate a gravitational field.