NASA Balloon Program Fact Sheet

National Aeronautics and Space Administration
Goddard Space Flight Center
Wallops Flight Facility
Wallops Island, VA 23337

For decades balloons have been used to conduct scientific studies. While the basics of ballooning remain unchanged, balloons have increased in size, and their dependability has greatly improved. The Goddard Space Flight Center's Wallops Flight Facility manages the NASA Balloon Program including management of the National Scientific Balloon Facility (NSBF) in Palestine,TX. Wallops provides balloons, helium and operational support for balloon launches from permanent launchsites in Palestine, TX, and Ft. Sumner, NM, and remote sites in the United States, Canada, Australia, New Zealand, and Antarctica.

NASA balloons are made of a thin polyethylene material, (.8 mil), about the same thickness as an ordinary sandwich wrap. Referred to as scientific balloons, they are very large. When fully inflated, they range up to 40 million cubic feet in volume and 600 feet in diameter and are taller than a 60-story building.The system includes a balloon, a parachute and a payloadthat carries instruments necessary to conduct a scientific experiment. Fully inflated scientific balloons, can carry a payload weighing as much as 8,000 pounds, which is about the weight of three small cars.



		How does it work? The balloon flight mission is relatively simple. The balloon is partially filled with helium and launched with the payload suspended beneath it. As theballoon rises, the helium expands and fills the balloon until it reaches full inflation.Two to three hours after launch, the balloon will reach peak altitude. As the balloon drifts across the sky, the experiment package in the payload gathers scientific data.When the experiment is complete, a radio command is sent from a ground station to separate the payload from the balloon. This creates a tear in theballoon material, destroying the balloon and causing it to fall to the earth. A parachute opens and floats the payload back to the ground. Recovering the payload allows the experiment package to be reused on another flight.

What's in the future?

The countdown has begun for Earth-orbiting balloons. NASA presently supports 25 scientific balloon launches yearly witha success rate in excess of 92 percent. The demand for scientific balloons is increasing. Balloons allow payloads tobe lifted without the vibrations and G-forces associated with rockets. The payload is recoverable which allows for multiple flights of the same instruments.

NASA presently flies conventional and long duration balloons. A conventional balloon flight will last from one to two days while a long duration balloon flight will last up to three weeks.These zero-pressure balloons are launched partly inflated and expand as they rise. They vent some of their gas as daytime temperatures rise in the stratosphere causing the balloon to expand up to its maximum design volume. As night approaches, the remaining gas shrinks causing the balloon volume to decrease and the balloon descends. In order to stay aloft, the balloon system must drop ballast. As a result, most zero-pressure balloon flights last for only a few weeks.

"Super pressure" balloons now being developed by NASA will float several-ton payloads through the stratosphere onmissions lasting more than three months. Like the zero-pressure balloons, the ultra-long duration balloon (ULDB) also will be partially inflated when launched. Unlike the zero-pressure balloon, which has venting ducts in the bottom, the ULDB will be completely sealed.

The ULDB will maintain lift, size and shape and will not react to atmospheric influences. Highly durable composite plastic and fabric materials currently being developed will make this possible. The new balloon material will be capable of withstanding high internal pressures caused by solar heating. With 20 miles of seams in the balloon, adequate sealing procedures also have to be developed that can be usedto fabricate reliable balloons from the new material.

Maintaining helium at a constant volume and density also will make the ULDB an extremely stable platform. The ULDB will allow scientists to gather more data over a much longer period. The first flight of the ULDB with a working payload is planned for November 2000.

Planetary Exploration

The new composite super-pressure balloon material will greatly enhance the prospects for use in planetary exploration. Planetary exploration is embarking on a new era using planetary aerobots. These unmanned scientific exploration vehicles a redesigned to float like balloons for up to several months in the atmospheres of planets.

This Fact Sheet is a publication of the NASA Goddard Space Flight Center's Wallops Flight Facility, Public Affairs Office.

For further information about NASA's Balloon Program call

(757) 824-1584 or visit the following Web sites:

http://www.wff.nasa.gov/pages/scientificballoons.html
http://master.nsbf.nasa.gov

June 1998



			Why use a ballooon? Balloons offer a low-cost, quick response method of doing scientific investigations. They can be launched from where the scientist needs to conduct an experiment and can be ready for flight in as little as six months. Experiments flown on balloons provide information on the atmosphere, the universe, the Sun and the near-Earth space environment. The scientific balloon also is a valuable tool in developing future scientists. Undergraduate and graduate students can conduct and complete a scientific study in the same length of time it takes them to graduate, two to five years.