The global horizontal sounding technique (GHOST) program was an atmospheric field research project in the late 1960s for investigating the technical ability to gather weather data using hundreds of simultaneous long-duration
balloon
A balloon is a flexible membrane bag that can be inflated with a gas, such as helium, hydrogen, nitrous oxide, oxygen, or air. For special purposes, balloons can be filled with smoke, liquid water, granular media (e.g. sand, flour or rice), ...
s for very long-range global scale
numerical weather prediction
Numerical weather prediction (NWP) uses mathematical models of the atmosphere and oceans to weather forecasting, predict the weather based on current weather conditions. Though first attempted in the 1920s, it was not until the advent of comput ...
[ in preparation for the Global Atmospheric Research Program (GARP).]
Technology
The GHOST program was to demonstrate technology for a program that would, ultimately, gather data from thousands of balloons simultaneously.[ Unlike ]radiosonde
A radiosonde is a battery-powered telemetry instrument carried into the atmosphere usually by a weather balloon that measures various atmospheric parameters and transmits them by radio to a ground receiver. Modern radiosondes measure or calculat ...
balloons which collect vertical atmospheric sounding Atmospheric sounding or atmospheric profiling is a measurement of vertical distribution of physical properties of the atmospheric column such as pressure, temperature, wind speed and wind direction (thus deriving wind shear), liquid water content, o ...
data over the release point during a relatively short ascent lasting a few hours, horizontal sounding balloons stay aloft for much longer periods lasting several weeks or months, floating at a constant-density altitude.
The GHOST design explored the performance a superpressure balloon with a spherical two-layer PET film envelope holding the gas inside at a higher pressure than the surrounding atmosphere, allowing it to maintain a nearly constant altitude. These gas balloon
A gas balloon is a balloon that rises and floats in the air because it is filled with a gas lighter than air (such as helium or hydrogen). When not in flight, it is tethered to prevent it from flying away and is sealed at the bottom to prevent t ...
s float at a constant density altitude
The density altitude is the altitude relative to standard atmospheric conditions at which the air density would be equal to the indicated air density at the place of observation. In other words, the density altitude is the air density given as ...
,lifting gas
A lifting gas or lighter-than-air gas is a gas that has a density lower than normal atmospheric gases and rises above them as a result, making it useful in lifting lighter-than-air aircraft. Only certain lighter-than-air gases are suitable as lift ...
due to solar heating[ is avoided in a superpressure balloon, since the inextensible PET film allows the pressure to rise as the gas is heated, rather than allow the volume to expand. This allows them to drift with, and track, horizontal atmospheric air currents at a constant air pressure level (a constant altitude) above the Earth's surface.
The electronics payload was suspended below the balloon on a tether that also acted as a ]high frequency
High frequency (HF) is the ITU designation for the band of radio waves with frequency between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters (ten to one ...
band radio antenna
In radio-frequency engineering, an antenna (American English) or aerial (British English) is an electronic device that converts an alternating electric current into radio waves (transmitting), or radio waves into an electric current (receivi ...
. The GHOST payload included a sun angle sensor that varied the repetition rate of its Morse code
Morse code is a telecommunications method which Character encoding, encodes Written language, text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code i ...
radio signal to allow technicians on the ground to locate it using an HF receiver and a set of sun angle tables.[
The balloons could not be flown in the Northern Hemisphere because the ]Soviet Union
The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
would not permit overflights at the time.
Results
231 GHOST balloons were launched in a four-year period between March 1966 and December 1969.Christchurch
Christchurch (; ) is the largest city in the South Island and the List of cities in New Zealand, second-largest city by urban area population in New Zealand. Christchurch has an urban population of , and a metropolitan population of over hal ...
, New Zealand by the U.S. National Center for Atmospheric Research
The US National Center for Atmospheric Research (NCAR ) is a US federally funded research and development center (FFRDC) managed by the nonprofit University Corporation for Atmospheric Research (UCAR) and funded by the National Science Foundat ...
(NCAR), continued to fly for an additional 76 days, completing 35 circumnavigation
Circumnavigation is the complete navigation around an entire island, continent, or astronomical object, astronomical body (e.g. a planet or natural satellite, moon). This article focuses on the circumnavigation of Earth.
The first circumnaviga ...
s of the Earth. The longest flight of the program was 744 days, or just over two years.
Legacy
For the measurements of the GARP program, the demonstrated flight lifetime at low altitudes (below ) proved to be too short, despite many redesigns of the balloon system to improve the performance. Without both upper level and lower level long-duration balloons, the GHOST system idea was deemed infeasible for the GARP requirements. The GHOST program was superseded by research on the carrier balloon system, also known as "Mother GHOST".American Institute of Aeronautics and Astronautics
The American Institute of Aeronautics and Astronautics (AIAA) is a professional society for the field of aerospace engineering
Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecra ...
in 2003 for his pioneering work in the application and development of superpressure balloons for worldwide atmospheric measurements, including the GHOST program.
References
Further reading
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*{{cite journal
, doi = 10.1175/1520-0469(1973)030<0003:TMUAFI>2.0.CO;2
, author = Solot, S.B.
, author2=Angell, J.K.
, year = 1972
, title = The Mean Upper-Air Flow in Southern Hemisphere Temperate Latitudes Determined from Several Years of GHOST Balloon Flights at 200 and 100 mb
, journal = Journal of the Atmospheric Sciences
, volume = 30
, issue = 1
, pages = 3–12
, issn = 1520-0469
, bibcode = 1973JAtS...30....3S , doi-access = free
External links
MSN Encarta: Ballooning
2009-10-31)
Balloons (aeronautics)
Uncrewed vehicles
Meteorological instrumentation and equipment
Scientific observation