LONG-DURATION BALLOONS

Long duration flight in the middle stratosphere is a well established need of the science community. Many balloon systems have been developed to satisfy this need, with varying degrees of success. This paper will review the requirements and those systems that have been suggested to achieve various mission goals and objectives. Each system has limitations of one sort or another. It is intended to place these various limitations into perspective so that the scientist may choose an appropriate existing system or recommend the development of an advanced system that meets his mission requirements. The status of current ballasted zero pressure balloon technology will be reviewed as a baseline from which other systems may be compared. Superpressure balloon programs will be reviewed as well as the hybrid systems that combine both types of balloons. Other systems such as the Radiation Controlled Balloon and the Montgolfier Infrared system have long duration capability with some altitude excursions. Each has a place in filling the needs of science today.