KSP Community CubeSat

[K^2]

Orbits around Phobos are going to be very tricky. It's far enough from spherical body to require constant corrections. It'd be possible to make a few turns, using propulsion to adjust trajectory, but for anything interesting, you need to land.

Fortunately, gravity is low enough that you can land on an electrostat, requiring minimal lithobraking if any.

[Rakaydos]

Orbits around Phobos are going to be very tricky. It's far enough from spherical body to require constant corrections. It'd be possible to make a few turns, using propulsion to adjust trajectory, but for anything interesting, you need to land.

Fortunately, gravity is low enough that you can land on an electrostat, requiring minimal lithobraking if any.

Electrostat will give 20+ millineutons for a reasonable weight of panels?

[dharak1]

Are we seriously considering a Phobos mission? Or is this still hypothetical planning fod funds+?

[Rakaydos]

Are we seriously considering a Phobos mission? Or is this still hypothetical planning fod funds+?

The important thing about the electrotetherm hwever, is that is brings our mission package together.

Mission 1: LEO plant lab/credibility check

Mission 2: LEO Elecrotether testing

Mission 3: Solar orbit mission and earth Aerocapture with electrotether

Mission 4: Mars Aerocapture with electrotether, possible phobos mission or phobos preparation mission.

Mission 5: Phobos mission.

So basically long term planning.

[Nicholander]

Yeah, we should talk about the Phobos thing on the other thread, but on this thread what should we talk about? How about the electrical systems like the MPU and such. I think there should be:

MPU (Main Processing Unit): It's the heart of the spacecraft, it receives commands given by us through the communications systems, and then sends them to the other parts of the CubeSat.

MMU (Main Memory Unit): It stores all the data and such, you might say it's useless and that we could just transmit all the data and memory to the ground, but remember: We only have one ground communications center, and we won't have a communications system capable of transmitting all the data in one go, so we need to separate the data into chunks to be transmitted during different pass overs of the communications center.

MPAU (Main Pressurized Area Unit): This is sort of like a mini MPU, but it's for handling the doing of the experiments and such in the pressurized area in the spacecraft, it can control the camera in the pressurized area, the water that goes to the plants, etc.

MCU (Main Communications Unit): This is a little area that gets the data received form the communications system, and sends it to the MPU.

MBU (Main Battery Unit): It's simple, the battery of the spacecraft. It get's power from the solar panels, and feeds it to the parts of the CubeSat.

Is there anything I missed or pointlessly put? I would look at this cool exploded view of ArduSat I found, but Google doesn't seem to be working for me.

[Nicholander]

Orbits around Phobos are going to be very tricky. It's far enough from spherical body to require constant corrections. It'd be possible to make a few turns, using propulsion to adjust trajectory, but for anything interesting, you need to land.

Fortunately, gravity is low enough that you can land on an electrostat, requiring minimal lithobraking if any.

Also, K^2, in one of my previous posts I said that during the Lunar flyby on our way to Mars or "Way to Earth" in Rakyados' 3rd proposed mission the CubeSat goes over the Lunar north pole to take some images of it, since there hasn't been any mission which has done that and the only photos of the Lunar poles are just a bunch of images taken from equatorial orbits that are glued together. How much would this affect the inclination of the Solar orbit, would it barley effect it at all? Or would it severely affect it so it would be impossible to reach our target?

[K^2]

Fixing fly-by to be polar would result in inclination and final heliocentric velocities being related. That can make something like an Earth fly-by a far more delicate maneuver, further reducing your options. I'm not sure how much it would impact an L1/L2 mission.

I feel like this should be one of these "one or the other" situations. If we don't think we can hit a target in heliocentric, then polar fly-by would at least mean it's not a wasted effort. But if we want to try and pull Earth fly-by, for example, then it's best not to restrict Lunar fly-by, and look for the optimal solution there.

[Nicholander]

So essentially, we should do an equatorial flyby, as a polar Lunar flyby would make the Earth flyby a lot more delicate. But, if we choose to do Rakaydos' suggested mission list, then we should do the polar flyby for the 3rd mission.

[K^2]

Not even straight up equatorial. It's all going to depend on the launch window and where the thing is heading. Choosing inclination of the fly-by trajectory is going to be a big part of the optimization routine.

[Nicholander]

Not even straight up equatorial. It's all going to depend on the launch window and where the thing is heading. Choosing inclination of the fly-by trajectory is going to be a big part of the optimization routine.

Okay, I should of said "Optimum", not "Equatorial". Also, what do you think we should do for the electrical compoments of the first CubeSat? Like MPUs and such. (Sorry if I changed the topic so quickly)

[Rakaydos]

General RFC. I'm putting together a shopping list. In principle, if we go with off-the-shelf CPU/MCU, we can go pretty fancy. But I think we are much better off by relying on architecture where any part can be swapped out to rad hard if funds become available.

With that in mind, I propose using an 8051 CPU. It's easy to work with. There is a huge amount of tools available. It will make floating-point computations a bit tricky, but honestly, everything we need can be done in fixed point. It also has very low clock rate, so we wouldn't be streaming any video. (Not that I was counting on that.) It will be plenty for navs and attitude control work, and it will be able to handle communications with ground stations and transmit images.

Best part, the off-the-shelf 8051 costs $10. So we can burn through a stack of them during development and testing without costing us. On the other hand, I've found rad-hard version of the same chip (UT69RH051) for $1,275. Expensive, but it's the sort of funds we might even find at the last possible moment, and still be able to swap out the off-the-shelf 8051 for a rad-hard one.

I'm still looking at memory and other components. But it looks like I'll be able to make an absurdly affordable base package which we will be able to expand into something far more reliable with a very reasonable stretch goal.

This was posted awhile back.

[Nicholander]

Errr.... Sorry. I forgot. Derp. Anyway, K^2, do you have any ideas on how to get our CubeSat project "More formal and organized"?

[sal_vager]

I'd settle for more exposure, and maybe sticking this thread for August will help do it

[Rakaydos]

Pehaps a clearer first post, though...so we dont get another flood of "Phobos? Why not titan!" posts when we've got a relatively solid set of missions planned (LEO plants, LEO propultion, Solar orbit wit aerocapture, and Beyond)

[technicalfool]

The way I see it, a first mission would be LEO or GEO only (unless you can fit enough fuel in a cubesat for something Lunar), and we could use a cubesat to test such things as manouvering, image capture and signal processing. Maaaaaybe see if we can test heat shielding and try a re-entry and recover for maximum science points, as it were.

On the second mission, see if we can get enough cash together for a Phobos mission. Not a Cubesat, a full size affair on its own launcher, or maybe hitching a ride on something big. Just to be doubly cheeky, see if a private operation based around a computer game community can get a probe to Phobos and returning useful science, before the big boys get Phobos-Grunt 2 there.

Now that would be a steal.

Edited August 1, 2014 by technicalfool

[K^2]

I'd settle for more exposure, and maybe sticking this thread for August will help do it

Yes, that might be useful, but as Rakaydos points out, it'd probably be better to have a new thread for it. This one was fishing for ideas. I think we are ready to do hard planning for basic mission, and that requires a different introduction with some more specifics. I'll need some time to go through this thread once more time, pull everything back together, and maybe get a few more ideas on components. I'll start the new thread once all of this is in order.

[sal_vager]

Okay K^2, PM me when you are ready and I'll stick the new thread, it's probably a good idea to link to this one so people can see how this started

[CaptainArchmage]

Just discovered this from the KSPTV channel. I think this is a great idea, and needs to go as far as possible! I might be able to contribute something too.

For propulsion: There has been this “Quantum Vacuum Thruster†or EM drive idea proposed. This seems to have produced positive results when tested by NASA and the Chinese. Because that doesn’t require any fuel to be carried on board, as long as the structure isn’t too heavy it could work on a cubesat. The power requirement isn’t very high (300 Watts - 3kW), so it could be acceptable for a cubesat mission, in fact it may not even that much power to be effective. It would require experimentation prior to launch, however, to have a reasonable confidence in the designs. The trajectory calculations to get beyond Earth Orbit would be more complex, however, because the spacecraft will be under continuous but very low acceleration, as with ion thrusters.

For computers: A lot of people have pointed out the need for radiation hardening. A lot of the space-rated electronics carry a large mark-up, so equipment that would cost $100 could be inflated in price to $10,000 or so, and be difficult to get a hold of. For the sake of keeping it economical, it may be better to use off-the-shelf equipment. This has been suggested a few times, I see.

For batteries: I’ve heard Lithium-ion batteries may have issues charging in colder conditions. Either alternatives should be sought, or some method should be found to keep the batteries warm.

Edited August 1, 2014 by CaptainArchmage

[Kryten]

The power requirement isn’t very high (300 Watts - 3kW), so it could be acceptable for a cubesat mission, in fact it may not even that much power to be effective.

The power budget for a cubesat is in the tens of watts, max. Of course, if we're suggesting incredibly dubious products of science-by-press-release, we could just dig up a cold fusion reactor and eliminate all power concerns.

[CaptainArchmage]

The power budget for a cubesat is in the tens of watts, max. Of course, if we're suggesting incredibly dubious products of science-by-press-release, we could just dig up a cold fusion reactor and eliminate all power concerns.

One could try to bring that down. The thrust requirement on a cubesat will be lower than on a large satellite. At the moment, with NASA having run the tests - it seems more believable than a cold fusion reactor. Then more testing is needed.

[Rakaydos]

I dont think it's our place to play with drives of uncertian physics. It seems too likely to draw the wrath of the kraken.

If an electrotether is viable on the first or second mission, however, it might be interesting to see what kind of maneuvering capability we can get out of only being able to alter trajectory at perigee. (is it possible to make lunar transfer by electrotether alone?)

[CaptainArchmage]

I dont think it's our place to play with drives of uncertian physics. It seems too likely to draw the wrath of the kraken.

If an electrotether is viable on the first or second mission, however, it might be interesting to see what kind of maneuvering capability we can get out of only being able to alter trajectory at perigee. (is it possible to make lunar transfer by electrotether alone?)

The thing about the device is - it is probably about as viable as the electrotether, if not more so. It would work in more circumstances We’d have do do some ground testing, of course - we should have reasonable confidence that the technology will work, and with the EM drive or QVT that should be possible. The difficulty besides understanding the construction of the thruster will be measuring low thrust levels - millinewtons or micronewtons.

There is also no reason not to equip both an electrotether and EM drive/QVT beyond mass. Only one of the devices should need to be powered at the same time.

If this is a long term project, then we should have the time to do such testing.

Edit: NASA’s efforts apparently produced about 90µN of thrust with 17W (Watts), which sounds like it is within the capability for a cubesat mission. Other tests done for Q-thrusters (there’s a different design, which is better associated with the theory) show micronewtons of thrust in that range - that still works, if you let the engine run long enough (months).

Edit2: There’s actually a probe mission for the Mars One project, which is supposed to go to Mars in 2018 or so. It might be possible for them to carry a cubesat project along.

Edited August 2, 2014 by CaptainArchmage

[Rainbowtrout]

I dont think it's our place to play with drives of uncertian physics. It seems too likely to draw the wrath of the kraken.

Well, if it were a movie we could use Hollywood's atomic technology of "Hollywood Physics".

[CaptainArchmage]

Well, if it were a movie we could use Hollywood's atomic technology of "Hollywood Physics".

.... except this is reality, and the device has been independently verified to the original designer. The physics of quantum mechanics is well understood at the moment.

If you want a thruster that is better tested, you can look at plasma. It uses a block of teflon, and an electrical spark to vaporise it. The energy is stored in capacitors, so the thruster is pulsed. The specific impulse is higher than the space shuttle main engines (I’ve seen about 500s quoted), but not as efficient as ion engines. The device should fit in the hand.

Another comment I have based on the first page:

Reaction wheels - I have seen a device that uses reaction wheels to stabilise a cube on a slope. However, on spacecraft reaction wheels need to be kept operational or have their angular momentum removed in conjunction with thrusters. They are also known to break, this is what happened to the Kepler telescope.

Edited August 2, 2014 by CaptainArchmage

[indroth]

Too late this year, but maybe next year?

http://www.smallsat.org/technical-program/workshop