Ugifer made a cool project for his kids, a high-altitude balloon equipped with a camera and a tracker so he can find it afterwards:
|"One of the coolest projects I have done so-far with my kids is a "near-space" balloon. That's not quite into space itself (100Km+) but so high that the sky looks black and you can start to see the curvature of the earth below you.|
In order to take this kind of photo you need to send a camera up to the stratosphere. Ours went 38Km (124,000 feet) straight up. This is easy enough: you attach it to a massive balloon, let it rise until the balloon bursts (due to the v. low pressure at the edge of the atmosphere) and then it will fall back to earth.
In order to see the photos that you have taken, you then need to find the camera afterwards. This is the trick.
Fortunately, at least in the UK and increasingly across Europe, the very helpful guys at the UK High Altitude Society (ukhas.org.uk) have developed a distributed network of trackers who will receive a signal from your balloon, upload the data to a server and plot the position for you on a Google Maps based page (spacenear.us/tracker/).
In order to take advantage of this wonderful network of helpers, we need to build a tracker that will communicate with their equipment. That is what I will outline in this instructable."