The earth from aproximately 90,000 feet. Dale Hollow lake in Tennessee is in the foreground.
Other photos here: http://www.flickr.com/photos/23663218@N06/sets/72157622749539273/
Weather Balloon - 2500 gram weather balloon made in 1984. -$35.00 (ebay)
Helium, 125 cubic feet - $55.00 (welding supply store)
Digital Camera - ~$60.00 (ebay) loaded with CHDK software
Cell Phone - Boost mobile cellphone loaded with accutrack GPS software- ~$45.00
Foam cooler - $3.00
Lithium Batteries - $15.00
Misc. - $10.00
I had been planning this launch for several weeks. I had been using the excellent flight path prediction software from nearspaceventures.com to estimate where the balloon might land. This is VERY important because the balloon MUST land where there is cellphone coverage; otherwise the balloon cannot report its location and will be lost. On this particular day, the predictor thought it would land in an area with good coverage, so I decided to have a go at it. I drove to the launch location, and the launch went off without a hitch at 1PM. I went back home and checked the accutracking information. The balloon had lost contact after reaching just 4000 feet! I went to fertilize the lawn to keep my mind off things. An hour later, I was nervously refreshing the accutracking page every few seconds hoping for a sign that the ballon had landed. I thought the whole flight would take about 2 hours, based on my assumed rate of ascent of the balloon. After 2.5 hours, I was sure all was lost. The balloon must have suffered some sort of failure, or most likely landed where there was no cell phone coverage. But then the online map suddenly updated. It had flown MUCH farther than I had expected. It was east of Jamestown, TN, about 120 miles from the launch site! We loaded up the truck with flashlights, ropes, ladders, and warm coats and started driving.
3 hours later, we were near the landing site. We stumbled through the cold, pitch-black woods and looked around at the presumed landing site for about an hour, but found nothing. Dissapointed, we drove back home.
Two days later, I drove back to look for it in the daylight. After hiking back to the GPS coordinates, the red foam cooler was easily visible. It was stuck in the top of a very high tree. The night before we had walked DIRECTLY UNDERNEATH it several times!!!!!
It soon became apparent tha tthere was no way I could get it down myself. I hiked back out and saw a white pickup truck passing by. I flagged it down and asked the guy if he knew who the owner fo the land was. He called the owner, who soon showed up with two other men. They seemed eager to help.
First they tried cutting down a dead tree near the balloon in the hopes that when it fell, it would catch the balloon and bring it down with it.
Then they tried doing the same thing with another tree.
The man then instructed his friends to "go and get some shells." I had no idea what this meant until they returned a few minutes later with an enormous rifle, complete with scope. The shot several rounds into the tree limb, as well as several rounds into the foam cooler itself, hoping to break it apart and drop the camera to the ground.
Finally they cut down the White Oak tree. I felt bad about killing a tree, but the camera probably would not have lasted through another rainstorm.
The camera took over 500 images throught the flight. Immediately after the ballon bust, the camera stopped functioning. I believe that the descent was violent enough to dislodge one of the camera's batteries, which I should have taped down securely.
A little explanation:
Weather balloons: These things come in a wide variety of sizes. Some are designed to be let go without carrying a payload. What you want are larger "sounding" balloons that are designed to carry scientific instruments into the stratosphere. The balloon I used was much larger than necessary. You could probably get away with a 350 gram balloon. As it ascends, the balloon gradually expands as the pressure around it decreases. It eventually bursts at high altitude, sending the payload back to the earth.
Lighter than air gas: Most amateurs use Helium. It is safe and readily availible. However, it is VERY expensive compared to Hydrogen. People who launch weather balloons every day (the weather service) use Hydrogen, since it is very cheap and has a slightly higher lifting capapcity. Flamability isn't a huge deal because the balloon spends only a short time on the ground.
Camera: I used a Canon Powershot G9 loaded with CHDK software. This software can act as an intervalometer, instructing the camera to take a picture every few seconds until the battery runs out. I attached an external power supply to the camera so I could power it with disposable lithium-ion batteries.
Batteries: Disposable lithium-ion batteries perform very well in extremely cold conditions, where regular alkaline batteries would freeze and fail. I also wanted to make absolutely sure that both the camera and cell phone would have enough power to keep working throughout the entire flight. Expensive, but worth preventing a power failure.
Tracking device: I went to Radio Shack and bought a pre-paid Boost Mobile Motorola i335 phone. It has a built-in GPS chip. I then installed "accutracking" software on the phone, which is totally free for the first month! This software lets you track the phone's location and altitude online. I set the phone to upload its location every minute. After launch, the phone soon got too high to communicate with cellphone towers, but once it landed, it reported its location, as well as all of the data it stored while it was not able to communicate with cell towers.
Misc: This includes fishing line from Wal-Mart, some tape, as well as an old plastic tarp that I made into a parachute.
Permit: As long as the balloon's payload is under 4 pounds, the string will break with force of less than 50 pounds, and the balloon does not fly into restricted airspace, no permit is required. There are a few other minor details that you should look up yourself at the FAA website (such as flights at night), but this is the gist of it.