KSP Community CubeSat

[Aethon]

The future of CubeSats. : http://www.nasa.gov/content/goddard/the-future-of-cubesats/index.html#.U-6ew_ldUTo

Origami for Cubesats. : http://www.nasa.gov/jpl/news/origami-style-solar-power-20140814/index.html#.U-6fdPldUTo

[Nicholander]

The origami thing, that's an interesting approach... Should we do that instead of 4 deploying solar panels?

[TheCanadianVendingMachine]

With the plant thing, what about Article IX of the Outer Space Treaty?

Check it

[K^2]

With the plant thing, what about Article IX of the Outer Space Treaty?

Check it

You mean the "contamination" clause? Anything that's going to disintegrate in upper atmosphere upon inevitable re-entry within a year from launch and has zero chance of spreading anywhere does not violate Article IX. There have been a number of satellites with living organisms launched with absolutely no contest.

(Edit: There are a number of other regulations based on safety and ehtics of using organisms for scientific research, and they are all fine with use of plants and invertebrates.)

The origami thing, that's an interesting approach... Should we do that instead of 4 deploying solar panels?

Simple centrifugal deployment involves fewer moving parts. Given that budget will be constrained, we need to go with the simplest system.

Edited August 16, 2014 by K^2

[christok]

I found what I was looking for in terms of using constants of motion for central potential as the canonical coordinates of perturbed potential. I'm going to write a 2D proof of concept, verify it in Mathematica, and then make sure that it actually gives me better results than simply integrating coordinates.

All I've done so far is create a few functions to return orbital elements for the conic approximation at a given point in time. I'm going to leave the advanced stuff until I have an idea of your maths, which will affect the code a lot. Not that I did much yet anyway.

By the way, just a reminder, all of the coputations should be done in double-precision.

Ah, yes. I started writing float (force of habit), thought better of it in the middle of the night and neglected to fix it so far. I was beginning to suspect you may call me out on it if you look at the code.

[K^2]

All I've done so far is create a few functions to return orbital elements for the conic approximation at a given point in time. I'm going to leave the advanced stuff until I have an idea of your maths, which will affect the code a lot. Not that I did much yet anyway.

Internally, orbits are going to be defined by the constants of motion, which are the time of periapsis passage (β₁ = T), longtitude of ascending node (β₂ = Ω), argument of the periapsis (β₃ = É), energy (α₁ = E), z-component of angular momentum (α₂ = L_z), and total angular momentum (α₃ = L). The convenience of using these internally is that they are constant for orbit around perfectly spherical mass with no other forces present. And when other forces are acting on the satellite, I only have to account for these in computations, dramatically reducing any errors. There will be methods available to set and grab current values for all of these.

Additionally, I'll have methods for setting (when appropriate) or getting some of the related quantities. Semi-major axis (a), eccentricity (e), inclination (i), mean anomaly (M), true anomaly (v), and current radius ®. The last three will be available based on current simulation time (t).

If you need references on any of these, there is an article on Wiki on Orbital Elements. I think, my notation is consistent.

Because it is convenient to keep time in seconds, and I don't want to bother with dates internally, I propose using Unix Time. So long as it's a double, there should be enough precision.

You can assume that you'll be able to just call a function to get any of these. What's irrelevant within simulation, and with which I will certainly not bother for now, are things like orientation of the reference plane and reference direction. For geocentric orbits, reference plane is just equatorial plane, so that part's easy. But reference direction is the first point of Aries, which moves with respect to Earth's surface. So that's going to be important when converting to/from GPS coordinates.

Ideally, once that's working, it should be possible to take satellite's trajectory and plot it over the map of the Earth to get something like this. Keep in mind map projection. I see no reason to do anything other than equirectangular, but most of the maps you'd find on-line are Mercator. It's a trivial conversion, either way.

Oh, one more thing. Altitude. Like I said above, radius will be computed, since it's relevant internally to how forces are applied, but altitude above MSL will require computing radius at MSL, which varies. It's probably good enough to just use geoid for that, since MSL only varies by a few meters with respect to that. But you'll need to dig up some sort of parameterization for geoid to make that work. If you don't want to bother, I'll probably get to that eventually, since altitude is relevant to drag estimates.

[ultimaterandombanana]

I had an idea about the plant cubesat idea. (not sure if it has already been suggested) We could find out the atmospheric pressure and percentage of certain gasses on Mars and then find the most durable type of moss/lichen and also put some soil similar to Martian soil, then see how it reacts.

[dharak1]

If our goal was to simulate the martian climate i think it would be too hard. It's easy to replicate the atmosphere and if we can get the details the soil. But when we get to amount of sunlight and temperature. I'm sure we could do it but finding a plant that wouldn't make it a waste would also be pretty difficult. I say we stick to microgravity experiments in Earth like environments for now.

[LvL]

We could find out the atmospheric pressure and percentage of certain gasses on Mars and then find the most durable type of moss/lichen and also put some soil similar to Martian soil, then see how it reacts.

Whoa whoa whoa, still gotta work on getting into orbit first, figure out what to do with the plant later. Like dharak said, we need to stick to experiments in earth orbit first. Also, how will we fit a plant in a 2U (even 3U) cubesat? how do we keep it alive? We will need to expose it to the sun for photosynthesis, but without the atmosphere the sun might kill it anyway. and how do we protect it from radiation? what about the temperature? will it even survive in zero-gravity? I say that having a plant is just too complicated. Stick to analysing the atmosphere and earth's magnetic field.

(sorry if I've missed anything, I'm new to the thread)

Edited August 16, 2014 by oarum

[dharak1]

The general consensus right now seems to be that we will be launching a 1U cubesat with .5 U dedicated to computers and attitude control and the other .5 U will be taken up by a small amount of moss but just under Earth-like conditions but with lower gravity provided by spinning.

[LvL]

The general consensus right now seems to be that we will be launching a 1U cubesat with .5 U dedicated to computers and attitude control and the other .5 U will be taken up by a small amount of moss but just under Earth-like conditions but with lower gravity provided by spinning.

that covers space and gravity, but what about everything else? We need constant water, CO2, sunlight exposure, and radiation protection! how will we have the budget to do that? and the spinning might mess up the orientation on the craft.

[dharak1]

The front of the craft will be open to light. The radiation isn't much of a problem for the plants but rad- hard electronics are preferable. We haven't solved the problem of water delivery and the level of Co2 in the chamber. I'm sure we will be able to keep the orientation in check when spinning.

[LvL]

I say that the first mission that we do should be a few thousand metres up into the atmosphere, and see if it can come back safely. also, if we are thinking about returning, would we need a heat shield?

[dharak1]

No cubesat has ever survived re entry. We won't be the people launching it either. Ideally it would go up on an ISS resupply and be launched from there by hand.

[LvL]

No cubesat has ever survived re entry. We won't be the people launching it either. Ideally it would go up on an ISS resupply and be launched from there by hand.

wouldn't we be able to find something cheaper than an ISS resupply rocket?

- - - Updated - - -

How about and inflatable heatsheild cube sat... a reusable cube sat?

^^^this^^^

[dharak1]

Too difficult. If by cheaper you mean Launching it ourselves then that is completely out of the question. If we can find a cheaper launch to LEO I'm sure we could use it.

[LvL]

talking about finding a piece of debris and deorbiting it.

^^^and that^^^

[dharak1]

Also too difficult. We would need very precise instruments too large or expensive to fit on our cubesat. This is something with the volume of a 1L pop bottle.

[LvL]

If by cheaper you mean Launching it ourselves then that is completely out of the question.

No, I didn't mean launching it by ourselves, that would be impossible, but we need to see if we can hitch a free ride before we pay anything for launching the cubesat. Even if we can't hitch a free ride, we can't go 'yep, NASA', we have to look at different companies for the cheapest prices. *yawn* going to bed now, 11 o'clock here.

Edited August 16, 2014 by oarum

[dharak1]

It would be preferable to have it lunched from a P-Pod on the ISS itself even if it cost a couple thousand more as long as we had the money.

[Nicholander]

that covers space and gravity, but what about everything else? We need constant water, CO2, sunlight exposure, and radiation protection! how will we have the budget to do that? and the spinning might mess up the orientation on the craft.

Water? It's partial gravity, so a water dispenser can be like this:

The water which they dispense will fall towards the side which they are closer to, and thus give water to the moss. I don't know if 8 is to much or to little, but Mazon Del what do you think?

[LvL]

Water? It's partial gravity, so a water dispenser can be like this:

http://i.imgur.com/Ab7qOZh.png

The water which they dispense will fall towards the side which they are closer to, and thus give water to the moss. I don't know if 8 is to much or to little, but Mazon Del what do you think?

how are we gonna protect it from radiation and expose it to the sun?

[K^2]

how are we gonna protect it from radiation and expose it to the sun?

You can't protect it from hard radiation, but the levels are acceptable for the duration we are looking at. UV radiation can be adequately shielded from with a sheet of glass.

Water? It's partial gravity, so a water dispenser can be like this:

I'm not sure we need this. Net water consumption will be limited by CO₂ availability. (Roughly, 6 CO₂ + 5 H₂O -> C₆H₁₀O₅ + 6 O₂ for cellulose synthesis.) We can't possibly bring enough CO₂ to exhaust all of the H₂O present as moisture in the soil or whatever substrate we will end up using.

[LvL]

I'm not sure we need this. Net water consumption will be limited by CO₂ availability. (Roughly, 6 CO₂ + 5 H₂O -> C₆H₁₀O₅ + 6 O₂ for cellulose synthesis.) We can't possibly bring enough CO₂ to exhaust all of the H₂O present as moisture in the soil or whatever substrate we will end up using.

but we will need to provide enough Co2 for the moss to survive.

[K^2]

There is only so much we can bring either way. And at some point, there will bee too much oxygen in there anyways. Point is, water isn't the limiting factor.

Alternatively, it might be a good idea to have something in there that converts plant matter back into CO2 and water. But we have to make sure that it doesn't mess with the rest of the experiment.

Just one more reason we really need to have a biologist for this.