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Figure 7.10 The Cosmic Ray Observatory
installation at Amundsen-Scott South Pole Station.
Cosmic rays are subatomic particles that hit Earth's
atmosphere and produce other subatomic particles,
including protons, electrons, and neutrons, the
latter of which can be detected at Earth's surface.
The South Pole neutron monitor is perhaps the
world's most sensitive detector of relativistic solar
cosmic rays due to its location at high altitude and
latitude. It is essentially closer to the space
environment than most other monitors on Earth. By
studying solar cosmic ray-produced neutrons
scientists can monitor solar activity and cycles.
(Credit: Paul Evenson, University of Delaware)
international facilities operated at many locations on the high Antarctic plateau.
It is also interesting to note that Antarctica is a rich source for meteorites, providing
astrobiologists with clues to the origin of life in the universe.
Some of the earliest accounts of astronomical observations south of the Antarctic
Circle indeed date back to Cook
s expedition, but those measurements focused on
navigation accuracy. By most accounts, modern astrophysics was ushered in by the
Australians in 1955, when cosmic ray detectors were installed at the recently
completed Mawson Station.
The term
'
is really a misnomer, however, as these rays are
predominantly energetic protons and helium nuclei. Showering down upon our
planet, these particles are guided by Earth
'
cosmic ray
'
field in much the same way
that electrons of solar wind origin are guided to the polar regions, producing auroral
displays. Entering the atmosphere above Antarctica, the protons strike air molecules,
mainly nitrogen and oxygen, and produce a cascade of new secondary particles that
include neutrons.
One of the early pioneers of cosmic ray research, and Antarctic astronomy in
general, was Dr Martin Pomerantz of the Bartol Research Foundation. He conducted
balloon-borne cosmic ray studies in the 1940s and 1950s and helped establish
neutron monitoring sites at McMurdo Station in 1959 and at the South Pole in 1964.
Neutron and cosmic ray monitoring has continued since those early experiments,
providing one of the longest continuous data sets. The South Pole Air Shower
Experiment (SPASE) in the mid-1980s continued the search for particles originating
from violent supernova explosions. More recently, neutron monitors at McMurdo
and Mawson stations operate as part of
'
s magnetic
, a worldwide network of
neutron detectors that provide real-time monitoring of cosmic ray distributions.
Such measurements are critical for understanding high-energy particles coming
'
Spaceship Earth
'
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