Monday, November 15, 2010

SPACE BALLOON

SPACE BALLOON - 2010

Flight projection:

Actual flight path:

The recovery climb (I am up in the branches):

The launch:

Landing spot:

Flight shots:








In early October my sister sent me an email with a story about a guy who had sent a camera into space and captured amazing photos on a shoestring budget. I immediately wanted to try it myself. Not only would this be an interesting challenge, but it would also be a great project for kids.

After a bit more reflection, however, I realized that this would not be such a breeze to pull off. The mission was to send a camera attached to a weather balloon outside of our atmosphere to capture the blackness of space. Eventually, the balloon will expand due the lack of atmospheric pressure, burst, and the “payload” will float back down to earth via a parachute. The electronics involved would have to survive 100mph winds, hours of flight in a wet environment, temps near 60 below, and the real risk of a water or hard landing. In addition to the camera, we would have to receive GPS tracking coordinates via a SPOT locater beacon. Needless to say, there were a few variables to overcome.

My friend Kevin Spence and I ordered the weather balloon, borrowed a SPOT tracker from another friend, Chris Bailey, and watched the weather to find a suitable launch date. I also took a cheap digital camera and loaded aftermarket firmware on it. This was basically a script that booted when the camera turned on and controlled the basics (shutter speed, flash, display, etc.), but also allowed us to create a time-lapse program that took a picture automatically every ten seconds until the 4GB card was full. We also used some chemical hand warmers to keep the electronics from freezing and hopefully to extend the life of the lithium batteries.



We had some nerd fun with the physics involved, as you can see from Kevin’s notes below:

Question: How full should we fill the balloon initially to get it up to 100,000 ft given its bursting diameter of 15 feet?

Analysis: Universal gas law: PV=NRT, P= Pressure (kPa), V= Volume(m^3), N= Mols, R= Gas constant (8.314 J/KMol), T=Temp in Kelvin

At 100000ft, P=1.10 kPa, V= bursting volume of 15 feet diameter or 50.03m^3 (volume of sphere 4/3*pi*r^3), N = ?, T =-46.5 Celcius (229.5 K) So we are looking at .0288 Mols of Helium will cause the balloon to pop at 100,000 ft. At 500ft elevation, .0288 mols of gas would be a volume of .685 m^3 (V=NRT/P). A volume of 685m^3 translates into a diameter of about 3.28 feet.

Answer: Filling the balloon to a diameter of 3.28 feet will get us to 100,000 ft. Unfortunately, I don't think this will lift our chicken as this volume of helium can only lift half a kilogram of weight which is how much the balloon weighs.

Question 2: A bottle of Helium will fill 70 12" balloons. How high can we get on one bottle of helium? (insert high school pot head joke here).

70 12" balloons represents a gas volume of 1.04 m^3. At sea level, 1.04m^3 of helium = .04376 mols. Bursting volume is the same at 50.03m^3, assuming it is around -56 degrees celcius (this temp seems to be the same over a large range of altitudes) so do the math and..... the pressure of this gas at the bursting volume = > 1.63 kPa. Look at the atmospheric charts and this is a little over 90,000 feet. (Interesting note, the atmospheric pressure drops by almost half between 90,000 and 100,000 feet)

Answer: One bottle of helium that will inflate the balloon to about 4.12 feet diameter will get the balloon up to 90,000 feet.

Question #3: So... how much will we be able to lift with a balloon that is 4.12 feet in diameter?

One litre of Helium can lift 1 gram of weight. We have about 1040 Liters of Helium so we can lift about 1.04 kg or 2.2 lbs. The balloon weighs .5KG so we have about a pound of weight to lift.

Answer: No chickens in space, we can only lift an additional pound of weight.

Anyway, based on the weather patterns and balloon projection models, we were certain that the craft was going to leave Eugene and head northeast. Our estimate was a flight of 50-80 miles and a 3 hour flight time. Our ship actually flew 70 miles over 4.5 hours.

After the kids made some drawing on the side of the ship and wrote a note explaining that it was not a danger, we slapped the components all together and let it fly on a overcast Saturday morning. We watched the craft sail out of sight and then followed it online via the SPOT tracking website. It steadily flew north for two hours and then (we presume) got well above 50,000 feet and was no longer able to pick up or transmit GPS signals. There was a long hour of complete darkness and then finally the track picked back up near Detroit Lake. Twenty minutes later we received multiple readings from the same spot . . . the craft had landed near Breitenbush Hotsprings, roughly 70 miles from Eugene.

Imputting our coordinates into Google Earth, we immediately saw that the ship was only a few hundred yards away from an unnamed logging road spur. It looked like the recovery was going to be a breeze. This was dead wrong. The recovery turned out to be ten times more involved than anything else. Despite clearcuts and young trees all around, the ship had landed in the top of some GIANT douglas firs. They were not old growth, but they were as close to that as they come for a second generation forest. We couldn’t even see the ship from the ground without binoculars. The tree was easily 200ft tall and the ship was about 150ft up. To put that in perspective, that is about the equivalent of a 12-15 story building just to the ship. The tree was simply a beast. We were clearly unprepared to get the craft down on our first visit.

After talking to a few arborists and doing some quick research, we decided to return with a full tree-climbing assault kit. I do a fair amount of climbing and mountaineering so I am quite comfortable with rope systems, but I had never attempted to climb a living, swinging thing like this before. Our plan was to use a giant slingshot to send a 60# monofilament fishing line over a strong branch, then drag a climbing rope over the branch, secure it, and ascend it as a fixed line. I would also be trailing a second rope that I would anchor through slings every 15 feet as a back-up. This second rope, my trailing line, would also extend above the fixed “top rope” and I could lead climb above the “top rope” using double rope pulley techniques or by climbing the branches and anchoring around the trunk.

It proved to be quite difficult to get the fishing line in place, because the lowest suitable branches were at least 100ft up. The line would get tangled, the drag would prevent it from descending back down to the ground, or the shots would simply be too far from the trunk (which I needed access to while climbing for additional protection). Even once we got the line in place it was equally hard to pull over a heavy, wet 80 meter 9.8mm rope. The weight and drag of the rope was immense. We also discovered that the 60# fishing line was not strong enough, so we pulled over nylon cord first, and then the climbing rope third. Eventually, after a lot of trial and error, we got the fixed line in place.
The lower part of the climb was difficult, the swing on a 100+ foot pendulum is huge and I had to keep myself near the trunk to tie on protection slings. Kevin was trying to belay me on my second rope while also keeping me in place on my fixed line. The fixed line was also super bouncy. The branches, while strong, did move when I tried to step up on the rope. It got easier as I got higher and was anchored in to the lower slings. It was definitely a gut wrenching ascent.

I eventually hit the canopy of the tree and all of the branches. This allowed me to almost place protection at will. I reached the top of the 80-meter fixed line which was at about 130 feet (Yes, we used every inch of the rope!). I removed my ascenders and began simply climbing the branches, setting anchors every ten feet. I finally reached the ship at about 150 feet. I swung a long sling with a carabiner out and pulled it in. I cut the remnants of the weather balloon free and finally had the payload in hand!

Some quick downclimbing and I was back to the fixed line. I put the free line through an anchor and got my rappel device on the fixed line. Kevin was able to belay me down while I simultaneously rappelled on the other line. I recovered every sling on the way down and finally touched sweet dirt again.

The electronics inside the ship were remarkably dry and we got over 2,000 pictures (although at least 600 of them are of a tree branch). A number of the shots are in the upper stratosphere and clearly show the blackness of space and even a bit of the curvature of the earth.

There were a ton of things that were sub-optimally designed or executed, but in the end we pulled it off for under $150. My son Boden seemed to love the pictures and the parachute, and who doesn’t like balloons? All in all, it was a cool, quirky adventure that may just have to be repeated!

9 comments:

  1. Awesome...just awesome. You are great dads - the kind of dad I hope to be. Thanks for the inspiration.

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  2. You guys are so cool!
    "Keep looking up!" :)

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  3. Awesome! I love what you did and the kids were involved. What a great adventure!

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  4. We read your account in the REGISTER GUARD. What a great
    feat, lesson and accomplishment!
    Congratulations!
    Keep us posted when you do more of these!

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  5. Hi,
    My name is Ryan and I go to Creswell High School where my class (SLAM) saw your experiment in the Register Guard and was greatly impressed. We would like to try it out and I was wondering if you would be wiling to give us some tips and pointers to help get us started. You can reach us/our teacher Mr. Wolfsen at: JWolfesen@k12.or.us

    Sincerely, thank you,
    Ryan

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  6. Make that email:
    jwolfsen@k12.or.us

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  7. That is Awesome,,,,NASA would make it a million dollar project. Way to Go,,
    Nobby 6 Crows

    ReplyDelete