KSP Community CubeSat

[Mazon Del]

Well here is a drawing for a sample container. Mazon Del can you give your input.

That is a reasonable enough approximation (some had little domes in the top or side for their lens), however the diameter of the container is much larger than necessary. 5-8 mm in diameter is probably sufficient depending on our desires.

MBobrik: Ah, sorry, thought I hit that one. The answer is we could, but we'd have to do quite a lot of testing to have confidence that the samples won't slide around or anything inside the holding space. The containers were designed to allow for jostling of the contents to some extent. We would of course need to test that configuration as well, just to verify that it meets our needs. One thing we have to remember is that unless the containers are being held in some sort of gimbal (it wouldn't be too hard to make one out of plastic and a thin 'captured' nail to be honest) on the ring, then chances are our best way of storing them during the ascent is to have the axis of the cylinder in line with the expected axis of thrust. Meaning that all the samples will try to end up on one of the walls. With the starting sucrose/moss mixture, this "should" be minimized though.

The sample containers themselves are, by design, open to the air around them. Though they can be sealed off if our needs require it. However, it would probably be best if we keep them open and have the ring area be contained. This way we can get air quality and gas-distribution information.

The moss itself actually utilizes very little air over a given period of time, mostly because its what we are starting with is going to be barely visible to the human eye and by the end of 2-4 weeks, should fill most of the 5mm x 5mm cylinder. "Most" is describing the good kind, where it is a 'fully grown' plant that gets us our data, not the kind of 'most' that implies we now have a cylinder of moss.

MrOnak: What is my current plan is that once we have settled on a tentative design for the growth chamber, I will print/build a mockup version of it. Luis will then provide me with some samples of moss to let grow inside the chamber for several weeks while I collect some data using instruments I have (we can cheat and have non-flight equipment here as long as the data collected somewhat resembles what we will be getting). With that data and the samples, Luis can apply (and believes he will easily get considering how long he's poked at them about the topic) NASA funding to have at least one grad student devoted towards breeding the specialized versions of moss that have an extreme gravitometric response in the up/down/perpendicular directions.

With this mockup, once Luis has the data he needs to apply for the NASA funding, I can torture the daylights out of the moss to get design data for us.

Newt: I think you are under the impression that people want to mount the camera onto the ring. The currently discussed method is that the cameras are fixed and will not move, and the ring will rotate to change which sample is in view of the cameras.

If MBobrik's calculations hold true, then there isn't really any reason we couldn't add a couple more cameras for both spare reasons and weight distribution reasons. Only cost and mass might really be issues.

[henryrasia]

Am I the only one who thinks this thread is getting crammed and hard to find info? @Endersmen, how's the website doing? Have you found an available computer yet? If not I hope you figure something out soon.

Again, the sat's orientation will determine a bunch of things. Where did the 100W figure came from? But regardless I believe starting a mockup experiment right now here on earth would be very useful, coupling with a camera test. I still feel one picture an hour came out of nowhere, from my very limited biology knowledge I recall moss gre quite fast. @Mbobrik, that data transfer calculations ignore power constraints, are you sure we can afford beaming down that many images every orbit?

@deljr15, that idea is pretty accurate, though it brings back up some old discussions. Since the sample ring (that looks like a donut, or a tube, what do we call it?) Is going to be circular, the gravitational gradient will not be negligible like it is on Earth. I calculated the vertical difference of a 5mm high Petri dish a lot of pages ago, and it turned out to be a lot greater than the maximum variation across planet earth. I still believe this will mess with the experiment. But besides that the gradient across 13mm of horizontal space will be much more noticeable (not to say the direction would change, no idea by how much though). My solution was to make the Petri dish concave to fit the ring nicely, I don't know how hard that'd be to do in solidworks, though.

Finally, it has a lid, which is like a normal Petri dish. Just so we're all in the same page, isn't each Petri dish going to be sealed airtight months before it even launches? Is that not the requirement for any cubesat launch?

Waiting for everyone else's feedback on this.

[MrOnak]

MrOnak: What is my current plan is that once we have settled on a tentative design for the growth chamber, I will print/build a mockup version of it. Luis will then provide me with some samples of moss to let grow inside the chamber for several weeks while I collect some data using instruments I have (we can cheat and have non-flight equipment here as long as the data collected somewhat resembles what we will be getting). With that data and the samples, Luis can apply (and believes he will easily get considering how long he's poked at them about the topic) NASA funding to have at least one grad student devoted towards breeding the specialized versions of moss that have an extreme gravitometric response in the up/down/perpendicular directions.

Thanks for clarifying this!

One thing we have to remember is that unless the containers are being held in some sort of gimbal (it wouldn't be too hard to make one out of plastic and a thin 'captured' nail to be honest) on the ring, then chances are our best way of storing them during the ascent is to have the axis of the cylinder in line with the expected axis of thrust. Meaning that all the samples will try to end up on one of the walls. With the starting sucrose/moss mixture, this "should" be minimized though..

This might be tricky, it's very unlikely that you can predict which side of the cube will be "up" during launch. depending on where you hitch a ride on the P-Pod may point up, diagonally or horizontally and any of the CubeSats six sides may end up "up". It all boils down to where there is space in the fairing next to the first class citizens with which the CubeSat hitches a ride.

BTW, what material will the "petri dish" be made of? Being able to hold the air in a hard vaccum, not cracking / deforming during the temperature range, and the extreme shaking during launch are all... shall we say... challenging for a 1mm thick plastic bit. At least that's what my gut says but I have absolutely no clue about material-stress calculations, just a thought that popped up. I think acryllic is formable from around 100°C but I might be wrong.

[MBobrik]

MBobrik: Ah, sorry, thought I hit that one. The answer is we could, but we'd have to do quite a lot of testing to have confidence that the samples won't slide around or anything inside the holding space. The containers were designed to allow for jostling of the contents to some extent. We would of course need to test that configuration as well, just to verify that it meets our needs. One thing we have to remember is that unless the containers are being held in some sort of gimbal (it wouldn't be too hard to make one out of plastic and a thin 'captured' nail to be honest) on the ring, then chances are our best way of storing them during the ascent is to have the axis of the cylinder in line with the expected axis of thrust. Meaning that all the samples will try to end up on one of the walls. With the starting sucrose/moss mixture, this "should" be minimized though.

I think we should avoid any jostling, moving, shifting, gimballing, any unintended and uncontrolled movement. The initial sucrose/moss spores mixture should be made stable enough to survive the gee forces of the launch even in perpendicular direction. Small size of the samples combined with the square/cube law should aid this. And because we will do a lot of testing of the mechanical stability of the sample holder anyway, we should go without capsules, inserting the moss directly to the compartments of the holder which will be molded as single piece of acrylic to simplify the design and to aid mechanical robustness.

However, it would probably be best if we keep them open and have the ring area be contained. This way we can get air quality and gas-distribution information.

Understand. How much volume of air per sample is sufficient ?

The only problem I see with doing away with sample containers is sealing the larger container.

Mazon Del said, the samples will share common atmosphere, therefore the larger container has to do all the sealing anyway.

[Mazon Del]

This might be tricky, it's very unlikely that you can predict which side of the cube will be "up" during launch. depending on where you hitch a ride on the P-Pod may point up, diagonally or horizontally and any of the CubeSats six sides may end up "up". It all boils down to where there is space in the fairing next to the first class citizens with which the CubeSat hitches a ride.

BTW, what material will the "petri dish" be made of? Being able to hold the air in a hard vaccum, not cracking / deforming during the temperature range, and the extreme shaking during launch are all... shall we say... challenging for a 1mm thick plastic bit. At least that's what my gut says but I have absolutely no clue about material-stress calculations, just a thought that popped up. I think acryllic is formable from around 100°C but I might be wrong.

My understanding is that the P-Pod will definitely have one of its axis's in line with thrust, and the reason we are to label one of the outside faces as "UP" is so they can put the sat in correctly aligned. For both P-Pod purposes, as well as forces alignment purposes.

Henryasia: The one frame an hour came from me as a BS-example, we are waiting on Luis to respond with how often images should be taken (its the end of the semester though, so he's bogged down with grading Finals). Though moss grows quickly, if our cameras are able to view the macro-cells in the moss type in question, then we shouldn't actually need a very fast rate of imaging because the shape of the cells themselves will tell the story.

The best way to imagine the sample container is to take a U shaped channel, and bend it into a circle with the 'walls' facing inwards.

There isn't much we can do about the gravitational gradient, however if we assume that our rotation is fairly well centered within the ring and is fairly constant, then we don't have to worry too much. In the images from the 'side' of the plant, we can have a computer draw out the expected gradients in post processing (on the ground computers) and draw our conclusions from that.

I do not know what the material of the capsules are made out of, I will ask Luis. The capsules should not be subjected to vacuum in an ideal situation. The growth chamber (with ring) should be pressurized.

[deljr15]

Mazon Del said, the samples will share common atmosphere, therefore the larger container has to do all the sealing anyway.

The problem becomes seal length. one big ring with a removable top (at least one side needs to open) will have approx ~500mm of total seal length. One small breach anywhere along that will result in mission failure.

Using capsules like the one below will give ~25mm seal length each. This will result in more total seal length 25*27=675 however if one seal leaks we only loose one sample.

Rev A of the sample

Another idea for holding them

Another note with this arrangement from the top of a sample container to the far corner of the cube should be acceptable for camera distance. We may need to have the camera slightly offset to view in (not sure if this will be a problem)

[MrOnak]

My understanding is that the P-Pod will definitely have one of its axis's in line with thrust, and the reason we are to label one of the outside faces as "UP" is so they can put the sat in correctly aligned. For both P-Pod purposes, as well as forces alignment purposes.

Hmmm, that's interesting, do you have a source for this? Not that I don't believe it but it pretty much contradicts what I've read and I want to know more.

That aside: The Cubesat has exactly one possible orientation inside the P-POD, that is, -Z side of the CubeSat is going into the P-POD first (spec. page 9, paragraph 3.2.2) and the side of the CubeSat with the access port (+X) is where the door of the P-POD is (design spec drawing in Appendix 1, section B vs. P-POD coordinate system on page 8).

So, marking something as "UP" is not possible.

So if what you're saying is right then the P-POD won't be mounted diagonally, but any of the six sides of the P-POD may be "up" at launch from how I understand it. Since the CubeSat's orientation inside the P-POD is fixed, my argument still stands I believe but I'll be happy if that's wrong.

Since I've checked the spec, the center of gravity of a 1U CubeSat must be within 2cm from its geometric center in all three axis (page 9, 3.2.14).

[Mazon Del]

The problem becomes seal length. one big ring with a removable top (at least one side needs to open) will have approx ~500mm of total seal length. One small breach anywhere along that will result in mission failure.

Another note with this arrangement from the top of a sample container to the far corner of the cube should be acceptable for camera distance. We may need to have the camera slightly offset to view in (not sure if this will be a problem)

That system is pretty much what I had in mind. We'd probably want something to support the capsules from the bottom (so as not to tempt fate).

As far as the smaller capsules, I'm really not sure that sealing the one hatch is that difficult of a thing to do. There are a lot of strategies we can do in order to get a double seal (or better) on the hatch. Plus, it is relatively easy to test if the seal is defective before it leaves our hands. Get the pressure sensor data streaming to a laptop, put the cube into a container and increase/decrease the pressure by a large enough amount. If there is a leak, it will be obvious.

Additionally, if we lose the large volume, then we lose all air-related data. No O2/CO2 readings. No pressure readings (pressure will change as the plants convert available food sources from solids to gasses, etc). Additionally, we now need to have localized heating/cooling systems across each capsule. Sure we can have them on a rotating basis, but I think this ends up being somewhat wasteful, plus it gets harder to get an accurate read on what temperature each capsule is exposed to.

To the best of my ability, after we have the finished sat, Luis and I will have a couple fake-sats sitting here on the ground acting as controls. As we get data on what the moss experienced in orbit (moss that would be the same generation as the moss in the controls) the systems at the control cubes would try to replicate it (heating or cooling the moss, exposing them to the same light levels [assuming we end up needing lights for image taking], etc).

Incidentally! Once we are getting closer to having a final design, one of our backer levels can include a mostly assembled (or not assembled at all) control-sat, maybe with same-generation moss (depending on logistics). So that anyone who wants can run their own version at the same time.

[MBobrik]

As far as the smaller capsules, I'm really not sure that sealing the one hatch is that difficult of a thing to do. There are a lot of strategies we can do in order to get a double seal (or better) on the hatch. Plus, it is relatively easy to test if the seal is defective before it leaves our hands. Get the pressure sensor data streaming to a laptop, put the cube into a container and increase/decrease the pressure by a large enough amount. If there is a leak, it will be obvious.

Additionally, if we lose the large volume, then we lose all air-related data. No O2/CO2 readings. No pressure readings (pressure will change as the plants convert available food sources from solids to gasses, etc). Additionally, we now need to have localized heating/cooling systems across each capsule. Sure we can have them on a rotating basis, but I think this ends up being somewhat wasteful, plus it gets harder to get an accurate read on what temperature each capsule is exposed to.

So we go with each sample sealed separately. Bu I still think that having separate small capsules like that is a waste of volume. If we plant the moss directly in the sample holder compartments, I think we can get far more sample volume and area without taking up more space in the sat. And the inner ribs that separate the compartments can be glued to the lid too, sealing any compartment completely, just like separate capsules.

I know, that my sketchup scratchings don't look that professional and sophisticated, but the entire construction is simpler, and that is a good thing.

[Mazon Del]

My most previous post brings up issues that having each space sealed from the others presents us.

I know, that my sketchup scratchings don't look that professional and sophisticated, but the entire construction is simpler, and that is a good thing.

You don't do yourself justice. That is a fine CADed container.

Incidentally, we are probably going to want to avoid adhesives if at all possible. Partly because that makes it impossible to reset if it is necessary (lets say the launch gets canceled because it missed its window, our next opportunity is another month or two later. It would be quite difficult to reset the moss without doing enough disassembly to make the payload specialists nervous. And also outgassing.

Mechanical seals with perhaps a veneer coating (in the vacuum section) might be fine. A coating that provides no difficulty for being removed if needed.

[MBobrik]

My most previous post brings up issues that having each space sealed from the others presents us.

Well, one common volume means one point of seal failure = mission failed.

Mechanical seals with perhaps a veneer coating (in the vacuum section) might be fine.

Unless we carve threads into the capsule part and screw the lid to it, mechanical seals are risky too. The sat will be rattled and shaken violently during the launch. And if one of the seals is shaken loose, the capsule will pop like a miniature bottle of champagne, hurling its lid and spraying its contents onto the circuitry, which is most likely instant mission fail too.

I think that better than gluing or purely mechanical seal, is to weld it together with suitable low melting point plastic.

[deljr15]

I know, that my sketchup scratchings don't look that professional and sophisticated

Don't beat yourself up. They dont need to look professional as long as they get the point across. Also I don't see anything wrong with your drawing.

Unless we carve threads into the capsule part and screw the lid to it, mechanical seals are risky too. The sat will be rattled and shaken violently during the launch. And if one of the seals is shaken loose, the capsule will pop like a miniature bottle of champagne, hurling its lid and spraying its contents onto the circuitry, which is most likely instant mission fail too.

I think that better than gluing or purely mechanical seal, is to weld it together with suitable low melting point plastic.

I agree on the threads. Also welding the lids in some way will be advantageous.

Incidentally, we are probably going to want to avoid adhesives if at all possible. Partly because that makes it impossible to reset if it is necessary (lets say the launch gets canceled because it missed its window, our next opportunity is another month or two later. It would be quite difficult to reset the moss without doing enough disassembly to make the payload specialists nervous. And also outgassing.

Mechanical seals with perhaps a veneer coating (in the vacuum section) might be fine. A coating that provides no difficulty for being removed if needed.

If we go with sample containers then we can just prepare another batch and swap them out. No need to open and reuse.

[Newt]

HenryRasia brought up a good point. Navigation in this thread, I am sure we can all agree, is difficult. Topics switch unpredictably, overlap with each other, and restart multiple times over the course of 189 pages of discussion. This makes it very difficult for newcomers like myself to figure out quite what is going on, and I am sure that it is also difficult for those who have been here longer too. We are not providing a welcoming place for interested newcomers, and yet we should be and we want to be. We just got a comment from another person who does professional designs using Solidworks (page 185), offering to help in a way that seemed more like a resumé than a mere statement of willingness to help. We, well, we greeted him.

That does not keep most people interested, and that person has not posted on the forum again (sorry for making you an example).

If establishing a website is impractical for the members of this team, that is fine. Setting up a good website takes effort, time and resources that not all of us can provide at the drop of a hat. What we have now, this forum, while not ideal for our purposes, has more potential than we are tapping.

I would move that we start additional threads on this forum. Different threads for major design topics: Experiment, Comm Systems, Computer Operation, et cetera, as well as a thread that serves as basic introductions, and questions and answers, for newcomers and interested community members. These could be linked in signatures, and at the OP's here and on all the others, that they may easily be found by those browsing the forum. The Q/A forum we would assign a moderator, from our ranks, who would either answer questions directly, or refer another team member to answer it.

This is not the best structure. But I think that we all can agree that our current arrangement is far worse.

We must recognize that that is alright. The project is growing, which is a good thing we can all agree. It is understandable to continue using a tool that has been useful in the past, but it would be a mistake to continue using that tool forever, even after we have exhausted its ability, and are no longer aiming at the same goal anyway. This thread was originally to gauge interest in a hypothetical project and discuss vague possibilities for it. That project has developed into a plan, a project with dedicated supporters and extensive research, design, and critique. This thread has served a valuable purpose. It is time that we not only acknowledged its limits, but did something about them.

-Newt

[henryrasia]

Thank you newt, that was a very eloquent post, and I agree to every word of it.

However, starting new threads would be, if nothing else, quite annoying to forum users not involved in this project but who nonetheless browse the science labs. Endersmen seems to be quite skilled in website making (far better than anything I could put up) but regrettably finds himself without access to a computer. If he can find a way around that it'd definitely be our best option. Until then, however, we can think about setting up our own vBulletin forum. It's free and without commitment: when we find a better alternative we just close it and move on. The website would be perfect, for example, as it already has different sections for different things, AND a dedicated file repository.

I'll leave it up to @Endersmen to discuss the details.

[NERVAfan]

That's a very good idea.

Let's leave this thread for the satellite itself and broader design questions (Where things fit, mass/center of gravity limitations, power limits etc.)

I've started a thread here for the experiment, sensors, moss survival conditions.

http://forum.kerbalspaceprogram.com/threads/103462-KSP-Community-Cubesat-Project-The-Experiment-Moss-survival-conditions-etc?p=1606234#post1606234

Somebody who knows something about programming or communications (not me) should start those threads.

[LordQ]

Been a while since I last posted, but I have been keeping myself up to date on things thankfully. Good to see that some 3D models have come out. I hadn't thought of picking up Sketchup for this - I'll make sure to grab it ASAP.

I do actually have some experience with forum administration and construction, so I'd be happy to set something up. I agree with henryrasia that it's probably a bad idea to start filling up this forum with our threads. Even one additional one, like we have now, is probably bad.

I actually administered a zetaboards forum though, so my preference would be to make a zetaboards forum if everyone is alright with it. If not, I'm sure I'll be able to figure out how to make a vbulletin forum just as easily. Do let me know.

[deljr15]

Well I don't know if this is applicable but I have an unlimited webspace server I am willing to donate to the cause.

Also we should pick up a domain mossat.org is not taken

[henryrasia]

Well, I've heard vBulletin is the best without going full professional. But what about a subreddit? That'd be easy, free, and has hierarchical comment structure, allowing for natural organization of priority discussions. Doesn't seem to support posting images, though. Regardless, that is awesome LordQ! We're lucky to have you aboard!

[Newt]

Could we get Endersmen to put up a site on deljr15's sever? Otherwise a separate forum might be a good idea. I agree about not wanting to clutter up the KSP page with all our project work.The nuts and bolts of online forum management are not really something I know much about, but I would gladly help setting up either a vBulletin Reddit, or Zetaboards page for us, if that is the decision.

While I was aware vaguely of the website's development, I was not aware how far it had progressed (or if it was at all past a mere suggestion). Getting Endersmen's input on that would be good, so we can actually see whether that would be possible.

Edited December 17, 2014 by Newt

[LordQ]

Alright, it looks like it'll have to be vBulletin for now. A quick google suggested it would be superior to a zetaboards forum as well. I'll get one started once I get home later today.

[MBobrik]

My most previous post brings up issues that having each space sealed from the others presents us.

Re-reading your previous post. Bringing the gases to the sensor(s) for analysis is definitely an issue. Thinking about a solution ...

[K^2]

I'm having some technical difficulties with my PC. That's setting me back with some work. I don't think there's any risk of me going completely dark, but I might be a bit useless for a few days.

[LordQ]

Sadly, I think we will have to go with zetaboards, as it's probably the best free option. Other free things like phpbb are nontrivial to set up. I'll go ahead and start up a zetaboards forum for us.

Does anyone have any suggestions for forum name btw? Currently I have Kommunity Kubesat, which just sounds ridiculous.

Edited December 17, 2014 by LordQ

[MBobrik]

Sadly, I think we will have to go with zetaboards, as it's probably the best free option. Other free things like phpbb are nontrivial to set up. I'll go ahead and start up a zetaboards forum for us.

Does anyone have any suggestions for forum name btw? Currently I have Kommunity Kubesat, which just sounds ridiculous.

I would suggest the same name as this thread.

[Nicholander]

Yeah, I'd suggest the same name too, KSP Community CubeSat. Also, just saying, there being multiple threads would be a bit harder to track and catch-up on for me, just saying. Also, why aren't you using vBulletin LordQ? Is it not free or something?