You'd probably want to tether the balloon somehow. A balloon I worked on stayed aloft for about two hours, but in that time it traveled about 100 miles. Even th

You'd probably want to tether the balloon somehow. A balloon I worked on stayed aloft for about two hours, but in that time it traveled about 100 miles. Even then, when it was above the horizon we could hear it with our equipment on the ground. I should note that the balloon only came down because it was designed to burst at a certain altitude and return under a parachute. Other designs that are meant for long or indefinite missions can last for weeks. As I understand it, other than lifting gas leakage the main limiting factors are energy (solved with solar panels, batteries, and smart usage) and balloon integrity under bright sunlight. As for quick deployment, perhaps there are ways to do it, but it took our (admittedly inexperienced) team of 15 or so about an hour to string up our payloads, fill the balloon to the right volume, and release it. Lots of fun, though.