High altitude ballooning is a great way to perform experiments in the near-space environment. High altitude ballooning is the process of using a free floating balloon to float through the atmosphere. Once can reach 100,000ft (30km) easily, and some technologies can bring you to 135,000ft (41km). Both Helium and Hydrogen are used frequently, depending on the mission. The missions using high altitude ballooning are commonly referred to as BalloonSat, as you a satellite of Earth on a balloon.