High-altitude balloon

High-altitude balloons are manned or unmanned balloons, usually filled with helium or hydrogen, or in some cases methane, that are released into the stratosphere, generally attaining between 18 and 37 km (11 and 23 mi; 59,000 and 121,000 ft) above sea level. In 2002, a balloon named BU60-1 reached a record altitude of 53.0 km (32.9 mi; 173,900 ft). High-altitude balloons are manned or unmanned balloons, usually filled with helium or hydrogen, or in some cases methane, that are released into the stratosphere, generally attaining between 18 and 37 km (11 and 23 mi; 59,000 and 121,000 ft) above sea level. In 2002, a balloon named BU60-1 reached a record altitude of 53.0 km (32.9 mi; 173,900 ft). The most common type of high-altitude balloons are weather balloons. Other purposes include use as a platform for experiments in the upper atmosphere. Modern balloons generally contain electronic equipment such as radio transmitters, cameras, or satellite navigation systems, such as GPS receivers. These balloons are launched into what is termed 'near space', defined as the area of Earth's atmosphere between the Armstrong limit (18–19 km (11–12 mi) above sea level), where pressure falls to the point that a human being could not survive without a pressurised suit, and the Kármán line (100 km (62 mi) above sea level), where astrodynamics must take over from aerodynamics in order to maintain flight. Due to the low cost of GPS and communications equipment, high-altitude ballooning is a popular hobby, with organizations such as UKHAS assisting the development of payloads. In France during 1783, the first public experiment with hydrogen-filled balloons involved Jacques Charles, a French professor of physics, and the Robert brothers, renowned constructors of physics instruments. Charles provided large quantities of hydrogen, which had only been produced in small quantities previously, by mixing 540 kg (1,190 lb) of iron and 270 kg (600 lb) of sulfuric acid. The balloon, called Charlière, took 5 days to fill and was launched from Champ de Mars in Paris where 300,000 people gathered to watch the spectacle. The balloon was launched and rose through the clouds. The expansion of the gas caused the balloon to tear and it descended 45 minutes later 20 km (12 mi) away from Paris. Manned high-altitude balloons were used from the 1930s to 1960s for research and in seeking flight altitude records. Notable manned high altitude balloon flights include three records set for highest skydive, the first set by Joseph Kittinger in 1960 at 31,300m for Project Excelsior, followed by Felix Baumgartner in 2012 at 38,969m for Red Bull Stratos and most recently Alan Eustace in 2014 at 41,419m. Unmanned high-altitude balloons are used as Research balloons. Common uses include weather balloons, as well as atmospheric and climate research. They are also widely used to collect data and imagery from near space. High-altitude ballooning is used for scientific applications such as submillimetre astronomy. High-altitude balloons have been considered for use in telecommunications and space tourism. Private companies such as zero2infinity and World View Enterprises are developing both manned and unmanned high-altitude balloons for scientific research, commercial purposes, and space tourism. High-altitude platform stations have been proposed for applications such as communications relays.