WASHINGTON — Scientists have long known of the potential risk from cosmic rays
and other aspects of space weather, such as streams of protons from the Sun, to
airline electronic systems, passengers, and crews. It has not been feasible to
quantify this risk, however, as systematic data are lacking on the actual amount
of rays and the charged particles and neutrons they create in Earth’s atmosphere
that are encountered during typical flights. Researchers have now begun
collecting that information, thanks to a newly developed instrument, the Low
Linear-Energy-Transfer Radiation Spectrometer (LoLRS).

The need to know the precise level of cosmic and solar radiation along air
routes has become more acute, as recent generations of commercial aircraft use
“fly-by-wire” control systems, managed by on-board computers, which are subject
to damage by high radiation levels. Future aircraft will employ even more
sensitive technologies, and will therefore be more susceptible to damage.

“This substantially increases the need to improve the definition of the
atmospheric radiation field as a function of location and time, and to reduce
the significant uncertainties associated with present day predictions,” says
Epaminondas G. Stassinopoulos of NASA’s Goddard Space Flight Center, lead
researcher of the project. Their report is one of the first papers published in
the American Geophysical Union’s new journal, Space Weather.

With the cooperation of Evergreen International Airlines, which flies long
distance cargo routes, LoLRS instruments have been flown aboard Boeing 747s
across the Atlantic and Pacific Oceans, across the United States, the length of
Africa, and, more recently, in the Arctic. Repetitive flights over the same
routes have enabled the scientists to begin studying the long term effects of
solar and environmental influences at aviation altitudes.

During each flight, every change in the plane’s altitude and direction is
recorded, because such factors as weather and traffic affect the exact route and
altitude of a flight, regardless of the original flight plan. It is essential
for the researchers to know the precise location, altitude, and time of each
radiation measurement.

Ultimately, Stassinopoulos and his colleagues hope to produce global maps that
reflect the dynamic nature of the atmospheric radiation field. This will require
the collection of a large quantity of data, and the researchers are therefore
developing techniques for analyzing the collected information. The research will
involve both aircraft and high altitude balloons that circle the polar regions
for long periods.

The preliminary tests have confirmed that doses of radiation from cosmic rays
and the particles they create are more intense at higher altitudes and at higher
latitudes; that is, they are strongest in the Arctic and Antarctic regions. This
is particularly true during solar storms, during which large quantities of
charged particles reach Earth’s atmosphere. The scientists hope that the new
study will go far beyond previous research in this field and facilitate the
construction of models that would be of real use for planners of aircraft routes.

AGU is providing free, open access to the journal Space Weather from its launch,
planned for 28 October, through 31 March 2004. The journal will include
technical articles, news items, feature stories, editorials, and opinion
articles. A quarterly paper edition will print a selection of the material
previously published online. Space Weather may be found at


For further information, see AGU Press Release 03-05 at