Near Space Flight Computer

[guest7146]

Hi everyone,

Near Space research and experimentation is an emerging hobby amongst electronic engineers and hobbyists.  The basic idea is that you fill a weather balloon with helium (or hydrogen) and then launch a payload with it into the very upper levels of the earth's atmosphere into a region known as "near space".  At this altitude (up to 40KM can be achieved) the curvature of the Earth can be clearly observed and as the atmosphere is beneath the payload (it's a near vacuum at that altitude), the blackness of space can also be seen.  The sky is effectively beneath the payload.

Most people launch a payload with a GPS tracking system and a cheap camera to snap cool pictures of the earth from space:



Very cool, as I'm sure you'll agree!

So, I wanted in on some of this action.  I decided to design and build my own flight computer that would support the following features:

1. real time GPS location tracking
2. real time radio communication for data exchange and commands
3. SMS control and data exchange
4. GPRS for real time exchange of data over the internet and tracking via google maps.
5. configurable sensor module support for data collection and scientific research
6. removable flash based storage for data logging and sensor/location logging

I'm at the prototype stage so far, and hope to do a first launch at the end of the Summer.

Here's my album so far:

http://www.amiga.org/forums/album.php?albumid=134

AH

[TheBilgeRat]

This is legal?!

I can't see this being ok in the states, at least not without all sorts of red tape.

[persia]

This is really what XMOS is built for.....

[guest7146]

This is legal?!

I can't see this being ok in the states, at least not without all sorts of red tape.

Yeah it's perfectly legal.  Weather balloons are launched all the time anyway - I think 2 or 3 times a day they launch those.  This is the same thing, except we're using the balloon as a method to achieve near-space experiments and photography.

Of course, you can't just go launching them willy-nilly.  You have to get approval from the aviation authority and then they give you a time slot that avoids any inbound/outbound flights.  So you have to get the date/time of launch approved, and you also have to get your launch site approved as well.
Here in the UK we have two sites that have blanket approval for launch, so as long as I use one of those I only have to obtain approval for the date/time.

I would imagine it's pretty similar in the US.  Certainly, people are doing launches over there.  Sparkfun did one too - and plainly advertised it.  I can't imagine them doing that if it was illegal.

AH.

[guest7146]

Mind you, the GPS design became quite interesting.  It turns out that GPS modules are limited in operating altitude and speed.  This is because the US don't want hackers and terrorists from developing home made sat nav guided missiles!!!

So, commercial GPS systems are limited to 80,000ft altitude and 515m/s speed.  If those limits are exceeded, the firmware in the GPS module shuts it down.

The second limit wasn't a problem for me - helium balloons don't travel very fast.  But the first limit was a right pain because I wanted GPS tracking above 80,000ft.

There were two options:

1. Design my own GPS module.  Since I would write the firmware, I could control when (if) the system shuts down.  This would be extremely complex and time consuming.

2. See if I can hack an existing system.

As it turns out, I did a bunch of research and I found one module that would only shut down if BOTH of those limits were exceeded at the same time.  So it had to be operating above 80,000ft AND travelling faster than 512m/s.  You could exceed either of those limits but not both.

That sounded a bit pointless to me, but hey - all I care is that I can use it above 80,000ft!



AH

[Franko]

You can find the basic guidelines here about launching a weather balloon in the UK. The main one being you need to give at least 28 days notice but they are rarely ever denied...

Getting Permission to launch a Weather Balloon in The UK

[Kesa]

I wonder what would happen if we tied a squirrel to one of those balloons and let em go up into space. Do you think their little heads will explode?   :roflmao:

[gertsy]

You can see the curvature of the Earth ?  What curvature?  The Earth is flat.
And if you send up too many of those things you'll make God and the Angles angry..!
Suggest we stay down here with the Squirrels.  A camera in a Squirrel hole now that'd be something.

[Zac67]

You can see the curvature of the Earth ?  What curvature?  The Earth is flat.

It's a disc and a disc obviously's got a curve, silly. :rtfm:

@OP
This is very cool - please keep us up to date, photos are very welcome!
What's your estimate on costs for a launch?

[guest7146]

@OP
This is very cool - please keep us up to date, photos are very welcome!

Okay will do!

What's your estimate on costs for a launch?

 I'd have to get back to the calculator in order to come up with a  figure for that, but you're right it would be very interesting to know.   I obviously know how much I've spent so far but it costs a whole lot  more to develop the thing than it will to simply create copies of the  finished article.

Also I haven't ordered my balloon and helium canister yet so I'm not quite sure how much that costs.

Let me assure you that I'm not rich though (I slog out in work every day like most people) and I'm just an individual working on this to my own budget.  So it's definitely well within the reach of others who share the interest.

When it's fully tweaked and perfected to my satisfaction I will be releasing the schematics, PCB designs and firmware for free (under an open source licence) so you'll be able to investigate it to your heart's content.

AH

[guest7146]

Maybe after I've got some experience under my belt we could send an Amiga up there just for fun ;-)

AH

[Zac67]

A 600 or CD32 could be quite feasable, but the extension cord will be a killer! ^^

[trekiej]

I heard about this about 5 to 10 years ago.
It sound cool.
Some fellows used a styrofoam cooler and some hand warmers in the unit.
I think Parallax.com had some info. on this a while back.
Maybe it was Nuts and Volts or Servo.