Near Space
by L. Paul Verhage
Approaching the Final Frontier
Near Space
The History of Cosmic Rays
The study of electrostatics was
our first step in the field of
electronics. In electrostatics,
electric charges are relatively
stationary. So, the natural philosophers (early scientists) who studied
the phenomenon of electrostatics
concentrated primarily on the
creation, storage, and interaction
between the two types of electric
charges. One of their tools was the
electroscope, a device consisting of
two metal foil leaves draped over a
metal rod and protected within a
glass jar.
Figure 1. The electroscope.
The electroscope indicates the
presence of electric charges by the
spreading of its two metal foil leaves.
The presence of charges of the
opposite polarity is indicated by the
collapse of the previously charged
leaves. If no opposing electric
charges are present, the leaves
should remain spread apart after
their initial charge.
Instead, it was discovered that,
once charged, the leaves of the
electroscope did not remain
charged. The electroscope slowly
loses its charge — no matter how dry
or clean the air. The source of this
discharge was unknown.
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Viktor Hess’ Experiment
On August 7, 1912, physicist
Viktor Hess began making balloon
flights with electroscopes onboard.
In his flights, he rode in an open
gondola under a hydrogen filled balloon to altitudes in excess of 15,000
feet. The experiments were not
without risk. The hydrogen in his
balloons was flammable and, at high
altitudes, he found that there was
less oxygen to breathe and that the
air would begin to get cold.
On these flights, Hess discovered that his charged electroscopes
would discharge more quickly at
higher altitudes. The effect became
apparent once his balloon climbed
above 6,000 feet and the interference
caused by natural radiation emitted
by the ground.
Hess’ electroscopes discharged
more quickly because the air was a
source of ions that neutralized the
charge on his electroscope. Since
the electroscope discharged more
rapidly at higher altitudes, he
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concluded the ionization of the
atmosphere increased as he rode
higher in his balloon.
The increase in ionization with
increasing altitude indicates that the
ionization is caused by an extraterrestrial source. In other words, there
was a source of radiation in space
that was ionizing molecules in the
atmosphere and causing his
electroscopes to discharge. This
same source of radiation was also
discharging electroscopes on the
ground, but more slowly than in his
balloon experiments.
In 1936, Hess was awarded the
Nobel Prize for his discovery of
cosmic rays, the extraterrestrial
source of radiation. Cosmic radiation
was a fascinating topic for people in
the last century. As I recall, there is
even an old black and white
Frankenstein movie that mentions
cosmic rays as being responsible for
the origin of life on Earth.
Initially, it was believed that cosmic rays were a form of electromagnetic radiation, like microwaves or
gamma rays. Electromagnetic radiation is carried by photons, which are
particles without rest mass or electric charge. Photons are not affected
by magnetic or electric fields.
However, since cosmic rays are
affected by magnetic and electric
fields, they must consist of charged
particles, like electrons and
protons.
It took several decades to
straighten out this error in books
written for the general public. I can
recall seeing cosmic rays listed at the
high end of the electromagnetic
spectrum in high school science
materials. Because of this cosmic
SEPTEMBER 2004
