K^2

Even 100m would be a stretch with what we can reasonably put up there. This is definitely for larger sats.

Considered already. I go through the math on previous page, actually. In short, would work for larger satellite, but not enough force to overcome drag on a cubesat. It might be possible to do a separation and rendezvous over a few meters. But would anyone actually find it interesting? The biggest problem is that there is no way in hell are we going to be able to actually find something up there, and even if we jettison something on purpose, once we separate by a few hundred meters, the physics of it becomes very messy. Accelerated frames of reference, etc. Well, if you've done docking in KSP, you have some idea. Now picture doing that remotely, with no decent range/velocity readings, and certainly without a map view. And that's just the logistics part of the problem. Actual propulsion/attitude control are going to be challenging as well.

One of the advantages of living in the United States is that explosives aren't illegal. Large quantities are a huge hassle, but what we'd need for something like this is entirely within reason. We'd have to convince whoever carrying it that it's safe to launch, of course. I can think of a few ways of making it as safe as any combustible, including monoprop. That said, just exploding stuff isn't efficient. It does give me an idea, though. I happen to know some people who used to work in explosions/combustion lab in Russia. That lab does have a project which I can only describe as an SRB that goes boom on purpose. I don't know if they ever worked out how to make it scale to an actual SRB size, but they have done small scale prototypes. I have zero idea of how to organize transportation even if we could convince these people to try it, but I'll write some e-mails. Maybe it can be replicated in the States. I don't know anyone certified to work with high explosives, though. This is definitely one of these far-side ideas, though. I just want to give it a benefit of the doubt until I have all of the info. I don't know how long it will survive, but if we can't get a budget for a good space-rated camera, that's essentially what I would have gone with. But only for photos, I'm afraid. There are all sorts of challenges with streaming video. Mostly, I'm worried about power drain.

I did some math on the tether. A 10cm x 10cm cross sectional area will generate 18μN of drag (ballistic model) and up to 7.8mA of current at 300km. (3x10-11kg/m³) At field strength of 40μT, which is pretty typical near Earth surface, that's just 0.3μN per meter of tether. So the tether would have to be at least 60 meters long just to compensate for the drag of the cubesat itself. And it will generate its own drag as well. The tidal force is barely sufficient at these scales as well. Tethered electromagnetic drive is obviously a workable principle based on these numbers, but not for a cubesat. You need a significantly larger satellite to do a good demo of it. Pity. It would have been a great project. But there are some other propulsion methods that can be looked into.

Do you see the LLO launches? Where do you think you cubesat will end up if you release it on LTO? That's as far as basic "I have money I want to waste," options. A GTO to LTO boost can be done with a cube for significantly less than paying for a GSO/LLO ride. So again, when "easier" includes funding the whole thing, yeah, escaping Earth is way easier than getting to GSO. But if you happen to have $500k you're not using, sure, lets put a sat in GSO.

If you think putting something in GEO is easier than putting it in Solar orbit, you understand nothing about orbital mechanics. We'll be very limited in terms of length of tether by the mass and size of the sat. I'll run the numbers. It'd be a great thing to try if we can get any serious amount of thrust out of it. There are a few other interesting LEO propulsion ideas that could be tried out. The force isn't actually that high. For a 3U, we'd be talking about something like 30-50N on average during maneuver. The heat is considerable, but nothing like a reentry. Mostly because you have thousands rather than hundreds of km you can use for braking. With some reasonable shielding, it's survivable. Control is a much bigger issue. Atmosphere isn't terribly predictable, and this is an extremely delicate maneuver. Still, you have about 30% of escape velocity for your error bars in general for a capture. This would require extendable heat shields that can be used in thinner atmosphere to increase drag, retracted in during passage through thicker atmo, where ablative shield in the front would be utilized, and extended again on exit. On exit, the shields/brakes can be extended more or less depending on how much velocity has been lost. It wouldn't allow for too much correction, but it will help. And I'll be honest here, a big part of it would involve getting lucky. That said, this mission ending as a streak of light in Martian sky, or with the cubesat bouncing off back into interplanetary space and getting lost there for good, would not be a shameful result. In fact, even if it ends almost two years earlier, as a crater on the Moon, I'd call it result exceeding expectations. But that only makes such a mission so much better fitted for a KSP community. If it succeeds, it would be against impossible odds. If it fails, it would fails spectacularly having done more than anyone expected of it.

Know what? That's a good idea. Tranceivers are much more reasonably priced than the solar panels needed to power them. And if worst comes to worst, I can pay for an MCU that will survive up there a couple of days out of pocket. It'd be nice to have ability to buy something specifically rated for space, however, so that we could count on it for a month of operation, at least.

Any of these ideas assume hitching a ride with a more serious launch. And some GTO-bound rockets do bring smaller payloads with them. It's just bloody expensive. I've found companies that done more reasonably priced LEO rides in the past, but I can't seem to find any of them advertising available cubesat space in future missions. GTO or LEO. Looks like we'll have to go door-to-door with this. Fortunately, not that many doors. We'll need to have some ideas prepared in advance, but we'd add stretch goals as necessary, not dump them all in at once. We'll work it out later. I'm sure we'll need a separate KicStarter topic just for figuring out everything involved with it. Might be useful to find some people with KS experience. Or maybe some marketing types to help us out, even. I know a few people. In this thread, we should work out a short list of challenges that we can try, and base line for how much each one would cost to try and achieve.

Sky, they are talking about finding a piece of debris and deorbiting it. Deorbiting our cubesat isn't an issue, of course. Even with ISS insertion, it will be gone after a few months to a year. Our hardware probably won't even live that long, though. Oh, and I do know all of the challenges of working with microwave transmitters/receivers, since I've done some lab work with these. Microwave interferometry in S-band, in fact. But I'll be first to admit that I know zip about how much difficulty atmosphere is going to add. I do know people in the next building over that do environmental studies that would know all about it, though. I also know the specs on TV receivers, and that we can't do worse than that if we try. So it's all details to be worked out as we get closer to it. The only serious obstacles are costs of launch and cost of solar panels, in that order. Because these are the things we cannot wing or fake in absolutely any way. These will have to be payed for by somebody in full.

The only reason I'm mentioning "ultimate mission" at this stage, is because I don't want us to end up like the potato salad guy, having no idea how to spend $50k on a potato salad. Scratch that, I would like to see us end up exactly like that guy, but I would like us to have a backup plan. LEO mission is more important to plan out in extreme detail. And right now, we still don't have a good objective.

And a magnetotorquer costs 600 Euro from the same people, yes. An S-band dish can be recycled from an old satellite dish for free. All you need is an actual generator and a receiver. Hell, I could build a microwave cavity for an S-band if need be, so only a transmitter really. And that's basically a microwave's magnetron that you can modulate. (Amateur S-band is actually at the same frequency as consumer microwave oven. You seriously can just turn a microwave oven into an S-band transmitter, but that's more of a fallback if we can't get funds for something better. FCC might not like us for using microwave. It's 'noisy'.) It might be a bit crude, but for sending something that's going to be a few hundred km away passing by, it will be good enough. Lets not forget that we don't need space-worthy for a ground station. Furthermore, I'm hoping for some support from existing CubeSat users. We do need to have at least one ground station, but it'd be nice if we could rely on other people to be able to receive tracking and image data from all over the world, so we can do data pulls more frequently. I'm going to take a closer look at available cubesat receiver/transmitter hardware before settling on protocol, but tentatively, I'd organize all of the important communications into packets of 2-byte symbols. I would chose a prime under 2^16 as a base, and have everything done in Zp of that prime. That lets me use some theorems on polynomials over fields that can be used for error correction. I could organize the packets so that at 50% random data loss, the data is not corrupt. Missing important instructions because of noise isn't nice. Of course, the only thing worse than not receiving instruction is receiving a wrong one, so each packet will come with a CRC as well, in case signal quality causes degradation that error correction can't handle. I'm not sure how paranoid we need to be about security, whether encryption should be used. We'll probably have to share a key with enough people to make it kind of irrelevant if we wish to get help form other users. And then it'd be just a waste of processing power. But we can talk about that. Unlike all other data that goes up and down, image downstream does not need to be as reliable, but it needs to be both compressed and error insensitive. JPEG, for example, would be a very bad call. An error early on would junk the whole data. But sending raw images is wasteful and slow as well. I'm leaning towards something JPEG based, but using something other than Huffman codes, so that decoding can resume after a loss. Maybe just run each tile in its own packet of Huffman codes, though. That'd make it super easy for an amateur user to build a JPEG out of it. And losing a tile isn't as bad as losing the whole image. Anyways, we can work on this. Everything else is fairly routine stuff. The Doppler factor for an LEO sat is whopping... 1.000025. I don't think we can afford a receiver/transmitter that wouldn't have a bigger window. Not even if we waste 10k Euro on a "professional" ground station. There is a reason why I'm starting with a cubesat hardware specs first. I can work out navs and logic once I have these specs. It's not that hard. Right now, I'm going through specific hardware for LEO mission, so I can put together an "official" shopping list and a price tag for the basic mission. Edit: Guys, deorbit is not feasible for the base mission. It's something we can try for if we have funding for much better hardware, but as it stands, I wouldn't count on being able to get closer than 10km to any given target. And that's with pretty decent off-the-shelf propulsion.

For LEO, it looks like magnetic torque is going to be enough for attitude control, which means that part can be practically free, yet reliable. So we're honestly down to solar panels as the only expensive bit. If we can get a free ride, a LEO mission is definitely doable. But I'm not liking the prices on the rides so far.

I'll take a look at what Russians are offering. They occasionally have discount com-sat rides. Might be possible to send something along.

Pretty much that. Though, panel arrangement might need to be different. It'd be nice if we can either use panels themselves or additional covers that go over them to assist in aerobraking. The launch cost of 1U to LEO from the service you've listed is also through the roof, though. There are definitely cheaper ways to launch to LEO. May be possible to find a cheaper ride to GTO as well.

That's quite a bit higher than I expected. Do you have a quote for that? On lithobraking on Phobos. It would probably work, but there is no way not to bounce. It would probably be ok if we have to land in a few small bounces at low speed, but at full speed, it might be a bit much. On the other hand, there should be sufficient time to kill if not all, then most of the speed using even an electrostat. So the actual landing might end up being a combination of the two.

cantab, good ideas. For propulsion, it'd probably have to be someone else's project. We can see if there are people who want to build/test something. A computer can be put into a cubesat, there are laptop mobos small enough, but we wouldn't be able to stream images back down. Rakaydos, anything that enters dense enough atmosphere will burn up. We don't have mass reserves to do heat shield or burn away enough delta-V. Anything with atmosphere is a valid target for an orbiter, however. Some, like Titan, are going to be extremely challenging, but simply due to the number of maneuvers it involves. In terms of delta-V, it's almost free. But a landing can only be done on something with very small surface gravity. Which is a problem, because that means no atmo to aerobrake against. That severely limits potential targets. Phobos is nice, because it has very low gravity, but orbits a planet with atmosphere. But there could be some other targets within reach.

Yes. I was thinking that as well. It might be much easier to get the $200k+ for extended mission after doing a simple LEO one. But it's never too early to plan ahead. Earth escape can be done in under 700m/s with Lunar fly-by. The 1.5km/s is what one would need for the Phobos orbiter/lander mission. But you are right either way. With bipropellant options not practical for a cubesat, this will require an ion drive of some sort. Most likely, an electrostatic thruster, which can give you 600s+ ISP. Unfortunately, most of these come with fuel pre-loaded and have pretty low total impulse. It might end up having to be a custom build. Hence such a huge gap in costs of the LEO and Lunar fly-by missions. But even 1.5km/s is achievable with an electrostat. So if we can get the budget, the option is on the table. Still, we need more ideas for what to do in LEO if we can't do a Lunar fly-by. Edit: The main problem with Venus impact mission is that a cubesat is not going to survive in that atmo very long at all. We'd be lucky to get one good data burst with mass spec from the outer most atmosphere. It's better than nothing, and would still make for the very interesting mission, but it wouldn't be my first choice. Of course, if Venus capture is the only good opportunity in the launch window we can get, then atmosphere analysis is probably the best mission we could do.

Honestly, no idea what to do there after landing. Not like we could bring an actual drill along. Might be possible to blast the surface with some gas and do mass spec on it for composition. It'd be kind of expensive, but not unreasonably so. That's the only thing I can think of that can be done with landing, but not with orbiter. Getting there is easier than one would think. Still not exactly easy, of course. The launcher would put cubesat on a GTO. Almost immediately, the main propulsion would kick in to change GTO to LTO. This would cost less than 700m/s of delta-V. That puts us on the course for Lunar fly-by. Except, at the top of LTO, the cubesat would be barely moving. Moon would sweep by and toss the cubesat out into interplanetary space going just a touch slower around the Sun than the Earth. Almost exactly a year later, Earth would catch up with the cubesat again. That's the Earth fly-by. If done correctly, that can toss the cubesat onto trajectory to intercept Mars. About half a year later, cubesat reaches Mars. Trajectory can be adjusted for Mars fly-by to have inclination that matches Phobos' orbit. A close fly-by allows aerobraking against Mars' atmosphere. That will take the cubesat from an escape trajectory to an orbit around Mars. A light boost at apoapsis would prevent further decay of the orbit. The most delicate part is the apoapsis itself, however. If it matches orbit of Phobos, the cubesat is already, effectively, on transfer orbit to Phobos. With a few adjustments and a bit of waiting, Phobos intercept is achieved. If all you want is Phobos fly-by or impact, you're basically there. If you want to orbit/land Phobos, you'll need to match its orbital velocity. From Mars transfer, that's 580m/s of delta-V. Total budget for lander/orbiter is under 1.5km/s from GTO to Phobos orbit. Total mission time, close to 2 years.

( A lot more discussion here: http://forums.mossat.org ) So, at the writing of this, the thread is nearing 150 pages of discussion. The poll is largely irrelevant to what was decided to be the first mission, but I can't remove it, so it stays. I'm going to post the rough outline of what we are working on. For a bit more details, some of the work is being organized in this document. Keep in mind, however, that it is very much WIP, and none of it is set in stone. Mission Objectives To construct a 1U Cube Satellite that adheres to standards necessary for launch, and have it launched and deployed to a stable Low Earth Orbit. To establish regular communication with the satellite via ground station. Be able to receive data, including images, from satellite. To gather data from an experiment that has some value to the scientific community. Standards General standards for CubeSats are available from CubeSat.org, but stricter criteria are likely to be imposed by the launch provider, which is to be decided. Standards of NASA's CubeSats Initiative can be referenced as a general guideline. Communication There are two main options for the on-board transceiver, both having amateur bands we can use. S Band - This is what people more conventionally think of when they think about communication with satellites. Unfortunately, all of the necessary hardware is insanely expensive. The ground station will also require a satellite dish to track the satellite as it passes overhead, which is very challenging to construct or very expensive to purchase. Either way, this option would require much better funding. The advantage is primarily in the data rate. If we want to be able to stream live video from the CubeSat, we have to go S Band. VHF - We would be limited to 200W on relevant bands, but this is sufficient to get the range we need. The hardware can literally be soldered together at home, and if we are worried about radiation, a VHF FM transceiver can be literally wired together with radio lamps that are rad hard by default. Cheap, reliable, and there are amateur radio operators using these bands all over the world that we might be able to ask for help if we lose the satellite. The disadvantage is that we'll be basically limited to a typical FM radio band, which will give us something like 50kbps - 100kbps. It's enough to beam down images, but we will not be able to do video. Experiment We are still working out details, but the most likely option is growing moss in hypogravity. A lot of experiments have been conducted on plant growth in hypergravity, and a number of experiments in microgravity have been conducted on the space stations. However, no experimental data is available for the 0g - 1g range. Certain mosses have very strong response to gravity, and there is interest in scientific community in obtaining some real data on that. It wouldn't be a huge contribution, but it would be something entirely unique that will result in some publications. Unfortunately, none of the people actively involved in this program are experts in the field. Hopefully, that will change. Hardware Frame - Commercial CubeSat frames are available, but very expensive for what they are. We are discussing possibility of custom tooled parts for the frame, but we need to make sure we can satisfy all testing requirements with these. Main Board - That will almost certainly have to be custom built, but fortunately, there are plenty of PCB printing services out there. CPU - There are a lot of options. The main limiting factors are cost vs ability to withstand radiation of LEO. If we can't afford it, off-the-shelf CPU/MCU will do, but rad-hard is preferable. Assuming we go with VHF option, which doesn't require a CPU capable of high data rate, I propose using 8051. First, because rad-hard versions are available for reasonable price, under $2k. Second, because garden variety of these is dirt cheap, and we can experiment with them as much as we like. Finally, they are easy to work with. There is a huge amount of development tools available, including C compilers and emulators. If we need to, a custom emulator can be written easily. Power consumption of just over 125mW is also a plus. The largest drawbacks is that it can only execute 1M instructions per second, limiting data rate it can directly beam to the ground station, and the fact that it can only address 64kB of memory. That's enough for everything but streaming video, though. Memory - Ideally, rad-hard stuff. The fact that we only need 64k with above is a plus, because that stuff also get very expensive. On the other hand, rad-hard memory isn't as critical as rad-hard CPU, so long as the code is written to take possible failures into account. Solar Panels - This is the place where we cannot go cheap. We will have to buy space-rated solar panels for a number of reasons. They are most exposed to solar radiation, they are a critical point of failure, and they can't shatter during ride to orbit. All of that adds up to panels designed specifically for space operations, and that means lots of money. Other than the launch, it is likely to end up the single most expensive part of the project. Batteries - LEO gives us 45 minutes of almost total darkness for every 45 minutes of sunlight. Battery must be capable of withstanding large temperature variations, frequent recharges, and still be able to power the satellite on the dark side. We will also most likely rely on the battery to provide power for the transmitter, since that's likely to draw way more power than solar panels can provide. It does seem, however, that we can find standard batteries for that, rather than reach for space-specific stuff. So while not exactly cheap, this should be relatively inexpensive. Navigation - We will need a GPS receiver on board. It needs to be unlocked to operate at LEO altitudes and velocity, but such units are available. Attitude Control - RCS is not really an option. Fortunately, we don't need to maneuver. Only adjust attitude. Magnetotorquers are available for that. Again, commercial units are unreasonably expensive, but I think we can handle coiling some wire. Mass distribution of the CubeSat will be designed so as to allow relatively complicated attitude adjustments. The CubeSat will constantly spin on one of the axes, which will allow for better stability, attitude adjustments via precession, and will provide small amount of artificial gravity for the experiment. Cooling/Heating - Some components are temperature-sensitive. We might need a thermoelectric cooler on board, attached to external radiators. Other than that, making sure that most of the sat is reflective should reduce temperature variations. Camera - It sure would be neat to get some pictures from up there. An external camera for cool shots would probably be a good idea. If sensible, an internal camera to watch over the experiment can also be added. It has been suggested that a microscope might be a good idea, which might be possible to swing. All of these will have to withstand radiation of space. Odds are, however, that we'll simply go for off-the-shelf versions and keep our fingers crossed. Typically, about a week of operation is to be expected from non rad-hard cameras, which should be sufficient to get a few cool pictures and get most of the relevant experiment data. Other Sensors - We can make use of accelerometers and light sensors to help hold/change attitude. Temperature sensors will probably need to be littered through the whole CubeSat to make sure we are aware of any problems early. Experiment will probably require a suit of its own sensors. (More precise temperature, pressure, humidity, O2, CO2, etc.) Software Almost everything has to be custom-written. I'm currently working on a simulation to help determine some of the requirements. In particular, these for navigation tolerances, mass distribution, amount of power we'll need for attitude control, and typical comm ranges to be expected. That simulation will also be used later to help develop software for the cubesat itself. If we are going with 8051, that will be coded on the very low level, with direct access to all the hardware on board. I will also work on software for tracking and communicating with the satellite, which we will try to make available to as many people as possible using amateur radio equipment. Funding Eventually, this will probably become a KickStarter project. We will need money to buy the parts, probably to pay for at least some of the testing, and finally, pay for a ride to LEO. That last one alone can be anywhere from $30k - $100k. There are, however, certain programs that give free rides to qualifying projects. We will look into that. No money will be taken from anybody until we finalize design, however. So hold your horses. All in good time.

The computer system will need to have capability to restart after a crash or power failure. That said, failure is always an option. Best we can hope for is a spectacular one. I need some sleep. Once I wake up, I'll make a thread. And yeah, I'll add a poll for the most feasible options based on assumption that we can get a GTO ride. If we can't, there is no way to leave LEO, so "where" isn't going to be an option.

Yeah. GTO to GEO is almost 1.5km/s. GTO to LTO is less than 700m/s. But the best part is that, in terms of delta-V, if you can get to LTO, you can go pretty much anywhere. Of course, precision, tracking, comms... Still, if we can make use of some radio telescopes every once in a while, that should cover the later two. And there are some, not inexpensive, options for a cubesat to give it sufficient precision and delta-V. What's really important here is that this is a craft that can take risks. It's not a multi-billion project, where if it misses a fly-by, it's a disaster. If we can put enough delta-V into it to make LTO, it's going to be awesome no matter what. If we miss by a lot, it will either become a really long period satellite of Earth or a new crater on the Moon. If we miss by less, it will become a satellite of the Sun. These are pretty cool outcomes for something crowd-funded. Especially if we can get some pictures and tracking out of it. But it wouldn't hurt to have the best-case-scenario mission planned out. If the Lunar and first Earth fly-by happen to go right, it'd be a terrible crime not to have a plan for the rest of the voyage, and timing will be important there, so it has to be planned out way in advance. Mars is the obvious next target, but there, one can either go for a fly-by, or aerobrake for a capture. Both allow for some great opportunities. But getting captured and transferring to Phobos would be the holy grail, IMO.

Somebody actually linked it earlier, but I haven't really looked at it yet. Problem is that it wouldn't be just planning a hypothetical. It needs to be possible to integrate with the rest of the software. But it's open source, so I might be able to pull out just the parts responsible for integrating trajectories and use 'em. Whatever they have in there is probably better than integrator I'd write from scratch. And it already has all the data sets to go with it. Yeah, I'll start one. Still gathering some info. Edit: Though, it's way, way early for KickStarter. For example, we couldn't put a minimum funding goal up right now, because we don't know if we can get a free ride to LEO even. That's a $30k difference. But that is one of the things that would be sorted in that thread, probably.

It's actually significantly easier, in terms of delta-V available, to do a Mars orbiter than a Moon orbiter.

Looking at some other numbers, with successful gravity assists, aerobreaking on Mars, and another 600m/s of delta-V, it'd be possible to land on Phobos. That would be pushing 3U to the limit, but it's the most insane, most Kerbalest thing I can imagine doing with the cubesat. I think, that should be the ultimate goal, with Mars fly-by/orbiter being one tier down. The sat would need some ability to adjust attitude, so that has to be in there at the base level. But I like the general progression. Getting an SRB burn seems kind of silly, but it fits with the KSP theme. If we can get funding for something more complicated, we try to get as much delta-V out of it as we can, trying to shoot for the Moon. Ideally, from a GTO insertion, so that there would be an actual chance of doing a fly-by. And if we have fly-by in the pocket, try to figure out what to do with the craft once it's orbiting the Sun. Some of these things can definitely be acquired cheaper, but with "some assembly required". I'm not entirely sure exactly where quality/weight are going to be critical. So what I'm going to do next is try to come up with hardware requirements for the above basic options, and then see how much of required assembly can be done by well-informed amateurs, and how much of it would have to go to the professionals. I'll probably start a dedicated thread, perhaps with some poll options, once I have some basic figures on costs/etc. Heh. I don't think I can run NASA-quality simulation on trajectories, but I should be able to write code that gets me close enough for maneuvering thrusters to make up the difference in transit. There will absolutely have to be a way to do proper tracking and send instructions for corrections in flight if we hope to go past the Moon. Edit: This is the sort of propulsion system that I'd be looking for ideally. It will fit in the 3U unit along with the payload and have enough dV to do Phobos landing mission. It's at the prototype stage, however.

Oh... Yeah. That's a great idea. Like, make custom mod parts and use the Solar System mod to show off flight path etc?