A balloon experiment consists of three parts. The balloon itself, a parachute to safely carry the scientific payload back to the ground after the flight is completed, and the instrument, often called the payload.

The balloons are made out of polyethylene that is only 0.8 mil. thick. This is about half as thick as ordinary plastic wrap, most of which is 2 mil. thick. These balloons can carry a payload weighing as much as 8,000 pounds (3,630 kilograms) - about the weight of three small cars. The size of the balloon used is determined by the weight of the scientific payload. These balloons are manufactured locally by Raven Industries, Inc., Sulphur Springs Balloon Plant, Texas. Quality control must be very strict and currently this is the only one place in the entire world that these balloons are made!

Figure 1. Scale Chart

Scientific balloons are considerably larger than weather balloons. An inflated weather balloon is only 3 feet in diameter and carries about 6 pounds.

Balloons can fly to an altitude of 26 miles (42 kilometers), with flights lasting an average of 12 to 24 hours. Special Long Duration balloon flights can last for more than two weeks. When the balloon reaches 50,000 feet, the temperature drops to -70 degrees Celsius (-94 Fahrenheit). However, at the balloon's highest altitude it gets somewhat warmed up by the Sun and the temperature rises to about -40 Celsius ( -40 Fahrenheit). Even though the temperature is still extremely low, there are often more concerns with the payload getting too hot than too cold. Since the air pressure is low (1/500ths of sea level pressure), cooling by air works much less well at ballooning altitudes than it does on the ground. So even though the outside air is very cold, it doesn't take heat away from the package very well, so the usual sources of heat (Sun, or the operation of electronics, etc. inside the package) can potentially cause the package to get very hot.