Arduino Balloon Satellite question.

Projects General Guidance
1

As far as weather or not an Arduino can be fitted with a GPS and a radio and transmit it's location from high altitude to the ground, I can reference the following Instructable. High Altitude Balloon Tracker Arduino

What I want to do would only start out with something like this. Obviously I plan to start with something similar and do some balloon tests to make sure all of my equipment and code works as I expect / intend it to.

After that's all been proven, the next logical step in my mind is to put it in low earth orbit and see how it fares from space. This is relatively easy to do with some creativity and crowd-funding. There are companies that are willing to take small payloads to low earth orbit and even NASA is taking cube-sats to space these days.

Having said that, I would still like to utilize GPS data if at all possible from low earth orbit. Otherwise, any readings my satellite takes, to me are somewhat trivial. Without knowing where the reading was taken, there's nothing to put on a graph. Having some coordinates would also make predicting the satellite's passes quite a bit more predictable.

This is where the problem seems to be however. It would seem that most if not all off the shelf GPS units are limited and they stop working above a certain altitude or above a certain speed. The best I can find seem to stop returning values when they exceed 50Km or 1,000Kts which is obviously fairly difficult to meet or exceed for an Arduino slung under a balloon. When you place something on orbit, though things change. Suddenly you're moving at around 17,000 miles per hour and you're closer to 400 Kilometers up. Both of these numbers are decidedly outside of both upper limits and thus the GPS will essentially stop working. What I want to know is if there's any way to get around this or if it's simply that's the rules and there are no exceptions unless you are a space agency or you're the department of defense.

Obviously, in the wrong hands, this type of thing is dangerous because the same technology could be used for weapon guidance, assuming you don't need to be more accurate than a few meters, but assuming this would be a tiny satellite with no attitude control, drifting in space until it inevitably burns up in the atmosphere, surely there's got to be a way I can make it happen right?

Seems a shame to go through all the trouble of building a somewhat sophisticated project, spend all that money to put it into orbit and then have no idea where it's at until I pick it up from my radio on the ground. I've done hours, days, weeks and months of searching, asking questions and sending emails to companies that build GPS units and other companies that build GPS breakout kits and nobody seems to have an answer for me.

Does anybody know if there's a way I can put a GPS unit in orbit and expect it to work?

I realize what I'm asking is pretty difficult, it's somewhat of my holy grail at the moment. Any ideas or suggestions would be greatly appreciated.

Thank you.

2

I'm not 100% sure what you're asking but here goes.

Firstly communicating with a high altitude balloon is surprisingly simple. Google for "Rock Seven" and you'll find some satellite modems, they're surprisingly cheap, and can be programmed as easily as a GSM module. I think it's about 10 pence for a 50 character message.

Secondly tracking. At low altitude weather will be a big factor, and you'll need GPS to track the balloon as it copes with the constantly changing weather, however as altitude increases weather is a lot more constant, so a lot of the time you should be able to predict where the balloon should be even if you don't know exactly. If your balloon is constantly rising and falling, then the occasional accurate fix when it descends may be good enough.

Thirdly, the Rock Seven modems will also give an approximate position of the modem (based on which satellite picked up the message) which is NOT restricted in altitude. however, this fix is normally given to an accuracy of plus/minus many 10s of kilometers.

3

The speed+altitude restrictions on GPS is intended to stop them being used for missile guidance. It's called ITARS, which is something about restricting international sales of weapons.

If you can sign a form to say that you won't be exporting it to any other country, then you can buy the appropriate GPS modules. They won't be cheap.

There's lots of cubesats floating around out there. I expect most of them use radio tracking and orbital ephermeris data to work out where they are rather than GPS.

4

Google for "Rock Seven" and you'll find some satellite modems, they're surprisingly cheap, and can be programmed as easily as a GSM module. I think it's about 10 pence for a 50 character message.

So you buy the module, then you pay to use it? It's a great idea and I can see it being very useful commercially, but for my application, I'll stick to gathering my own data over ham. It's a lot cheaper to get set up and I don't have to rely on other satellites or pay third parties to relay my data. There are already global amateur groups that do this for free, you just have to find the right group to join.

There's lots of cubesats floating around out there. I expect most of them use radio tracking and orbital ephermeris data to work out where they are rather than GPS.

This may end up being the way I go too. I'm also looking into possibly arranging for the satellite to blind plate solve it's location using an onboard camera and a dedicated computer, though I realize how calculation intensive and inaccurate that could prove to be. Everything is still very much work in progress at this point.

If you can sign a form to say that you won't be exporting it to any other country, then you can buy the appropriate GPS modules. They won't be cheap.

If we were to assume that money were no object, where might I locate the aformentioned "Appropriate GPS module"? This is still something I really would like to do if at all possible, but I simply have not yet found a company that will even talk to me about such a GPS unit. Not to mention the department of defense and united states air force are horrible about answering any civilian inquiry of this nature, even if you've found the appropriate inbox to send said inquiry to.

I'm not planning this completely by myself, I have a small group of local makers that are all interested in the project and we are all researching and building things to get a better understanding of what this is going to require. We are also planning to crowd fund launch costs if needed and of-course construction costs. I would still like to keep the cost as low as possible though we are probably looking at around 10k USD just for the launch, if we go through InterOrbital systems.