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High altitude ballooning, 70k feet and above.

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Patrick

Tue Nov 22 2011, 03:32AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

ive always wnated to get FAA permission to attempt the flying a balloon above the armstrong line trick. but how to get it all back is the question, now theres this....

A pet finder, uses GPS to text or email you the location of the collar on your pet. All for a one time cost of100 USD, so unless someone can show me a cheaper easier way todo the same i think this is the best devvice ive seen so far.

now we can all find the balloon's hardware (camera) and see space from our own devices!!!

Nicko

Tue Nov 22 2011, 06:57AM

Registered Member #1334 Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615

We live out in the countryside and have a GSP (German Shorthaired Pointer) that will happily go on jaunts of 10 miles or more after dark - he would come back a few hours later exhausted.

I always wondered where he went, so a couple of years ago I got one of these tracking collars - you had to add a suitable SIM card and it sent regular SMS messages (every minute) that you could then extract and input into Google Earth to get the actual tracking.

Brilliant - ISTR that was about USD 100 as well.

Oh, he seemed to go down to the water meadows on the river about a mile away and chase rabbits.

Tetris

Thu Nov 24 2011, 01:41AM

Registered Member #4016 Joined: Thu Jul 21 2011, 01:52AM
Location: Gainesville, FL
Posts: 660

You could put a really loud alarm onto it and wait. Hee hee. Or if you have a really old phone with GPS capabilities...

klugesmith

Thu Nov 24 2011, 03:25AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

now we can all find the balloon's hardware (camera) and see space from our own devices!!!

I guess the boundary of space -- Armstrong line or Karman line -- is a subject of debate. Either altitude will show a plenty-dark sky.

But the curvature of the Earth's horizon, in pictures from amateur balloons, is mostly an artifact of barrel distortion in the camera. It happens when a lens, especially a wide-angle one, is aimed below the horizon. A camera in the same place as this picture was taken, if tilted upward, would show the horizon to be concave upward.

That can be fixed in Photoshop:

Here is a respectable paper about visualizing curved horizons from high altitude.

Can anyone here explain how curvature is measured in spherical geometry?
I expect that a great circle has zero curvature, and a small circle (such as a non-equatorial parallel of latitude) is curved toward the nearer pole. A rainbow has an obvious curvature. The Earth's horizon has a much smaller curvature, which is perceptible above some altitude - some say around 40,000 feet.

Conundrum

Sat Nov 26 2011, 06:52PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

Isn't GPS limited to 15K feet?

-A

Turkey9

Mon Nov 28 2011, 04:13AM

Registered Member #1451 Joined: Wed Apr 23 2008, 03:48AM
Location: Boulder, Co
Posts: 661

The accuracy of GPS decreases above 15K feet, but can still be used even in low earth orbit. However, I think that he will be using the GPS to find the satellite after it comes back to earth in the middle of some unknown field.

Conundrum

Mon Nov 28 2011, 10:30AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

heh...
"Your balloon is in... GPS location n. " Hmm.. thats only 25 feet away from the sewage farm... OH CR*P!!!!!!

In terms of cheap GPS modules, those Bluetooth GPS boxes are pretty cheap now in the sales.
Take out the battery and wire the GPS module (serial output) directly to a micro, then use a gutted Nokia 3310
or similar el cheapo phone fitted with a worldwide PAYG SIM and 3*AAA Li+ in series and you have a Â£20 tracking device.

All the micro needs to do is send a text with a copy of the NMEA sentence every two hours and it should be possible to locate the
point of impact of your wayward balloon by getting the phone to send SMS at an altitude of
about 250 feet using an optical distance sensor.
Which knowing my luck will be in the middle of an ocean, yielding 0% chance of recovery.

(what are the odds of it landing on the deck of a passing cruise liner?!)

-A

klugesmith

Mon Nov 28 2011, 07:05PM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

Isn't GPS limited to 15K feet?

You'll appreciate this one, Conundrum.
I'd read that consumer GPS receiver modules (hardware + software ) are required to not work at extreme altitudes or velocities.

Just found one set of compliance limits in ITAR (International Traffic in Arms Regulations).

Under Category XV-Spacecraft Systems and Associated Equipment
we find
(c) Global Positioning System (GPS) receiving equipment specifically designed, modified or configured for military use; or GPS receiving equipment with any of the following characteristics:
(1)...
(2) Designed for producing navigation results above 60,000 feet altitude and at 1,000 knots velocity or greater;
(3)...

Ain't the Internet fun? I still think the international market for Arms Regulations is small.

Steve Conner

Mon Nov 28 2011, 07:11PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I thought people had already flown GPSs like this. Maybe they only crap out at 60,000ft AND 1000 knots.

"I appear to be on an ICBM. Quick, call the White House!"

Conundrum

Mon Nov 28 2011, 09:02PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

Problem is, if the thing is falling at 1000 knots (highly likely) then it will not work.
Which is unhelpful as this normally means the balloon just burst and the payload is heading groundwards very fast.

Of course my preferred workaround would be to put my payload at the end of a long half wing and the memory cards on the other so it spins round like a sycamore seed and slows down that way.
At least then the memory cards should survive even if the electronics disintegrate on impact.

Bonus, put a linear CCD array along one edge so it takes pictures as it spins

-A

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