Science research and balloons

A great many balloon flights of the twentieth century focused on science and particularly the sun and cosmic rays. Balloons could provide a stable instrument platform free from the vibration and the electrical interference generated by aircraft engines. They could also climb above most of the Earth's atmosphere and measure atmospheric and cosmic conditions without atmospheric interference.

Much of our knowledge of the universe began with a 1912 balloon flight that physicist and professor Bruno Rossi called "the beginning of one of the most extraordinary adventures in the history of science." On August 7, 1912, Austrian physicist Victor Hess took three electroscopes up to 16,000 feet (4,877 meters) in an open balloon basket. With these instruments, which detected and measured radiation, he made an unexpected discovery—high-energy particles not seen on the surface of the Earth were bombarding the upper atmosphere. He concluded that "a radiation of very great penetrating power enters our atmosphere from above" and is absorbed by the atmosphere before reaching the Earth's surface. These particles received the name “cosmic rays” in 1936 by physicist Robert Millikan of the California Institute of Technology (Cal Tech).

In 1914, Charles Greeley Abbot, director of the Smithsonian Astrophysical Observatory, sent specially designed instruments that measure solar radiation into the upper atmosphere to study solar energy and its impact on the Earth. Since the Earth's atmosphere absorbs much of the light and radiation from the sun, balloons helped Abbot study solar energy by taking instruments above most of the atmosphere—15 to 20 miles (24 to 32 kilometres) above the Earth's surface.

Jean Piccard, Auguste Piccard's twin brother, led a research team on the 1933 Century of Progress balloon flight that included two U.S. Nobel laureates, Arthur H. Compton of the University of Chicago and Millikan, who would soon coin the term “cosmic rays.” The scientists provided two instruments that measured how well gasses conducted cosmic rays. The balloon also carried a cosmic ray telescope that determined the direction where the rays originated, a polariscope that investigated the polarization of light at high altitudes, equipment to take air samples, single-celled organisms and fruit flies for tests for genetic mutations, and an infrared camera and spectrograph to study the ozone layer.

Jean Piccard and his wife and collaborator Jeanette Piccard flew on the second Century of Progress flight in November 1933

Jean Piccard was given the Century of Progress balloon after the flight. In 1934, he and his wife and collaborator Jeanette Piccard flew the reconditioned balloon on another research flight. Their 1934 experiments included a burst apparatus to study the simultaneous bursting of lead atoms bombarded by cosmic radiation. Millikan supplied a cosmic radiation experiment--an ionization chamber shielded with 700 pounds (318 kilograms) of lead dust.

During the worldwide depression of the 1930s, organizations and researchers such as Jean Piccard concentrated on developing better equipment for atmospheric research. Piccard teamed with physicist John Ackerman at the University of Minnesota to improve the latex rubber balloons then used and started experimenting with plastic film balloons. At the time, the only plastic available was cellophane, which tended to crack during cold weather inflations. They also tried using multiple latex balloons to lower the cost of balloons. On July 18, 1937, Piccard piloted the Pleiades on a successful low-altitude test flight. His gondola was carried aloft by 92 latex balloons.

Most research stopped during World War II. When the war ended, Piccard returned to his work on plastic balloons. In 1947, he received funding from the Office of Naval Research (ONR) for the Helios project. Helios would consist of 80 to 100 plastic balloons that carried a sealed gondola as high as 100,000 feet (30,480 meters). Working in a wartime-created bombsite laboratory at General Mills in Minneapolis (the cereal company), Piccard worked with Otto Winzen, a young man he had met in 1946 while visiting the University of Minnesota's aeronautical laboratory, to find a suitable plastic for their balloons. They finally decided on polyethylene and then worked on how to manufacture balloons from sheets of this plastic that were only 1/1000 of an inch (0.0254 millimetres) thick.

On September 25, they launched the first large balloon since the end of World War II. The first in a series of four launches, the polyethylene balloon had a capacity of 100,000 cubic feet (2,832 cubic meters), but carried only 70 pounds (32 kilograms) of equipment. The next two test launches failed. On the fourth launch, the balloon refused to descend for three days, and the high-altitude controls, radio equipment, and insulated containers malfunctioned. The delay was a goldmine for cosmic ray researchers. Two Brookhaven National Laboratory physicists, J. Hornbostel and E.O. Salant, had flown a pair of cosmic ray plates on the mission, and they were delighted with the results that the three-day delay brought. The success of their experiment led the ONR to abandon the idea of human balloon flights and focus on unmanned research.

From 1947 on, polyethylene plastic balloons demonstrated their superiority over natural or synthetic rubber balloons for high-altitude flights. The lightweight and reasonably low-cost means of lofting instrument payloads to altitudes of more than 100,000 feet (30,480 meters) made it easier for researchers to conduct scientific experiments above 99 percent of the Earth's atmospheric mass that could measure atmospheric and cosmic effects without interference. Cosmic ray physicists were the first to use these new plastic balloons. From 1947 to 1957, literally hundreds of cosmic ray instruments and photographic plates were carried aloft under polyethylene balloons.

After the Brookhaven physicists, one of the early researchers was Dr. James Van Allen of the University of Iowa physics department. In 1952, under an ONR grant, he developed “rockoons” to extend the altitude from which data could be collected. Rockoons are balloons that carry sounding rockets—rockets that are launched straight up from the Earth and that carry instruments to observe and measure various natural phenomena. By launching the sounding rocket from a balloon at an altitude of 70,000 feet (21,336 meters), Van Allen could send instruments up to 300,000 feet (91,440 meters). Van Allen used sounding rocket technology when he measured the energy in cosmic rays and the interaction of cosmic radiation with the Earth's atmosphere near the North Pole. His team launched the rockoons to altitudes between 20 and 70 miles (32 to 113 kilometres). As the rockets fell back into the atmosphere, they returned data to the scientists below on cosmic rays, pressures, heat, and other conditions. These early experiments suggested the existence of trapped radiation in near-Earth space. This trapped radiation was later confirmed by satellites and became known as the Van Allen radiation belts.

Skyhook was one of the first major programs to take advantage of the new balloon technology. On August 19, 1957, an unmanned Skyhook balloon lifted a cargo from the Stratoscope project, a program developed through the National Centre for Atmospheric Research (NCAR) with the cooperation and joint sponsorship the National Science Foundation (NSF), the U.S. Navy, and the National Aeronautics and Space Administration (NASA). The main instrument was a 12-inch (30-centimeter) telescope with a special light-sensitive pointing system and a closed circuit television camera that researchers could guide—the first balloon-borne telescope. The telescope took more than 400 photographs of sunspots. These were the sharpest photographs taken of the sun up to that time. The photographs increased scientists' understanding of the motions observed in the strong magnetic fields of the sunspots.

At sea on the flight deck of the USS Valley Forge, the Skyhook Project crew prepares the electronic gear for attachment to the balloon skyhook.

During the second part of the twentieth century and into the current century, balloons have gathered data used by researchers in many discipline areas. Instruments on high-altitude balloons have carried out magnetosphere research and studied the magnetic field around the Earth and how it interacts with cosmic winds, as well as studies on micrometeorites and cosmic dust. Simultaneous flights of balloons launched from widely separated locations have mapped plasma flow and the interaction of plasma wave particles. Instruments carried by balloons have performed planetary observations, visible light particle sampling, and pressure-temperature sensing.

Balloon instruments have answered questions about the concentration of ozone, carbon dioxide, carbon-14, nitrous oxide, and ratios of oxygen and nitrogen in the atmosphere above 100,000 feet (30,480 meters). They have measured trace constituents in the stratosphere that reveal ozone depletion from manmade propellants in aerosol sprays and the emission of nitrogen oxides from jet aircraft. Geophysicists and earth scientists have used balloons to monitor earth resources, take pictures from the air, and study light from the aurora and constellations. Biologists and aerospace medical specialists have sent plants and animals into the upper atmosphere via balloons.

During the Cold War, balloons were used to collect data on atmospheric radiation levels. The Atomic Energy Commission's Project Ash Can, with some co-sponsorship by the Advanced Research Projects Agency (ARPA), monitored radioactivity in the environment. Launched in 1956, Ash Can used polyethylene balloons designed by Otto Winzen to collect particle samples in the stratosphere. These samples were tested for the presence of radioactive dust raised by nuclear blasts and nuclear bomb tests.

As part of the Stratoscope program, a series of three 10-million-cubic-foot (283,169-cubic-meter) Winzen balloons were launched from the deck of the Valley Forge aircraft carrier in the Caribbean starting on January 26, 1960. These huge thin-film polyethylene plastic balloons lifted cosmic ray research equipment weighing two tons (1,814 kilograms) for the National Science Foundation (NSF) above 100,000 feet (30,480 meters).

On March 10, 1960, the Office of Naval Research (ONR) and National Centre for Atmospheric Research (NCAR) sent Coronascope I, another solar instrument package, to 80,000 feet (24,384 meters) and a second coronascope aloft on May 3, 1964, under a 32-million-cubic-foot (906,139-cubic-meter) balloon.

Stratoscope II was an even more ambitious project. The balloon carried a 3.5-ton (3,175-kilogram) astronomical observatory that took high-resolution celestial photos. Launched on January 13, 1963, the balloon's 36-inch (91-centimeter) telescope transmitted infrared spectral data on the Moon, Mars, Venus, six giant red stars, and other space phenomena. The information gleaned from the Stratoscope and other balloon explorations changed existing astronomical theories on the evolution and structure of the stars and the characteristics of the planets.

In January 1959, Project Stargazer began to study high-altitude astronomical phenomena from above 95 percent of the Earth's atmosphere, which allowed undistorted visual and photographic observations of the stars and planets. On December 13-14, 1962, Captain Joseph Kittinger and astronomer William White rose to an altitude of 82,200 feet (25,055 meters) over New Mexico in the Stargazer gondola. In addition to obtaining valuable telescopic observations, the flight provided useful information relating to the development of pressure and associated life support systems during an extended period on the edge of space.

During the second part of the twentieth century, giant plastic balloons built of better materials were able to carry heavier cargoes higher and higher. These giant balloons were so tough that they carried instruments through 155 mile per hour (249 kilometres per hour) jet stream winds and temperatures as low as minus 86 degrees Centigrade (minus 123 degrees Fahrenheit). They were exposed to the full force of cosmic and solar radiation and proved remarkably reliable. By 1972, the largest balloons had a 53-million-cubic-foot (1.5-million-cubic-meter) capacity, measured 750 feet (229 meters) tall, had 24.8 miles (40 kilometres) of heat-welded seams, and could carry seven tons (6,350 kilograms) of instruments to low altitudes or lighter packages to 31 miles (50 kilometres).

In 1970, the United States launched more than 500 high- and constant-altitude balloons. In addition to x-ray, gamma ray, infrared, and ultraviolet instruments, balloons have also carried instruments performing neutron spectroscopy and those that have counted micrometeorites. On October 16, 1970, an x-ray telescope from the Massachusetts Institute of Technology (MIT) lofted by a 34-million-cubic-foot (962,663-cubic-meter) balloon remained above 148,000 feet (45,110 meters) for more than 10 hours.

One of the most unusual flights of the 1970s, combined science and art. Vera Simons and Rudolf J. Englemann, a National Oceanic and Atmospheric Administration scientist, planned a series of four Da Vinci flights to study atmospheric structure, turbulence, and pollution; the suspension of fine particles in clean air; gather landscape and cloud images for art; and demonstrate the balloon as kinetic visual art. Their second flight, Da Vinci II, launched on June 8, 1976, and travelled the length of the St. Louis plume, an air pollution band, for 24 hours.

In 1960, two years after the National Aeronautics and Space Administration (NASA) was established, the NCAR was organized in Boulder, Colorado, under the sponsorship of the National Science Foundation, to coordinate the activities of more than 40 universities engaged in atmospheric and cosmic research. Among its activities, the organization has coordinated work in balloon construction, instrumentation, telemetry, and tracking and has launched some of the largest plastic balloons to date.

The Stargazer gondola was supported by a 280-foot-diameter sphere of Mylar film

NASA also maintains a significant scientific balloon program. NASA's Scientific Ballooning Program plays an important role in the agency's scientific investigations into the upper atmosphere, high-energy astrophysics, stratospheric composition, meteorology, aeronomy (the science of the physics and chemistry of the upper atmosphere), and astronomy.

NASA uses large unmanned helium balloons to explore the atmosphere on the edge of space and to place scientific instruments and equipment into space. Balloons make an inexpensive platform for developing new technologies and payloads and are quick to construct. They also have more flight opportunities than rockets, satellites, or human missions and provide more accurate vertical flight profiles, although satellites provide broader area coverage. Balloons have been important for the development of spacecraft and spaceflight instrumentation. For example, the coronagraph used on Skylab (launched on May 4, 1973) was the final improved design stemming from earlier balloon-borne models.

In 2000, two balloon experiments sponsored by NASA, MAXIMA and BOOMERANG, determined that the Universe is geometrically flat; will expand forever; and comprises about five percent ordinary visible matter, thirty percent dark matter of an unknown nature, and 65 percent dark energy, a mysterious force that is accelerating the expansion rate of the Universe.

Cutting-edge cosmic radiation balloon research continues to the present day. On January 4, 2001, NASA launched TopHat successfully from McMurdo Station, Antarctica. TopHat is a hat-shaped experiment that sits on top of a main balloon and carries the Advanced Thin Ionization Calorimeter for Louisiana State University. The balloon circled above Antarctica at 120,000 feet (36,576 meters) for two weeks collecting light from the cosmic microwave background radiation. Observing the microwave background, which was formed 300,000 years after the big bang, enables scientists to understand the nature of the Universe when it was an infant. TopHat is just one of many balloon cosmic radiation experiments. The Advanced Thin Ionization Calorimeter, another balloon experiment that Louisiana State University has flown over Antarctica, gathered data on galactic cosmic rays.

Boomerang was a cosmic microwave background (CMB) payload that was listed by the National Aeronautics and Space Administration as one of the top 10 science discoveries in space science in the last five years

Other research includes NASA's Ultra-Long Duration Balloon (ULDB) program, which has had two test launches from Alice Springs, Australia, in early 2001. ULDB is the largest single-cell, super-pressure (sealed) balloon ever flown. Made of a newer lightweight polyethylene, the balloon is partially inflated with helium at launch and expands as it rises. It uses enhanced computer technologies, high-tech materials, and advanced design for long-range (around the world), long-duration (100 days) flight. The ULDB floats at 115,000 feet (35 kilometres), three to four times higher than passenger planes and above 99 percent of the Earth's atmosphere. The project has been testing the balloon material on these launches and has determined that modifications to its composition may be needed. When the project becomes operational, ULDB experiments will study the source of cosmic rays generated from supernovae shock waves and survey X-ray-emitting objects in the universe.