Evening star., 1953-12-28
Shooting Sturs Offer
New Radio Roof
Study Makes Possible
Many New Frequencies
BY Thomos R. Henry

The thousands of shooting stars
which hit the earth's atmosphere each
hour are providing q new radio roof"
for the world.
This has just been reported to the
Offlce Of Naval Research here by DR..
Oswald G. Willard of Stanford Univer-
sity, who Is investigating the field un-
der Navy contract. This roof, which
reflects radio signals. makes possible,
he says, reliable short wave transmits
sion over distances up to thousand
miles "a hours day throughout the
year without Interruptions due to at
mospheric conditions at high attitudes.
It is well known that long distance
transmission of any kind is possible
only because of series Of electrified
layers in the upper atmosphere which
are created by radiation from the sun.
From these layers, radio waves are
bounced back to the earth, which
bounces them back into the air again.
Otherwise they would pass into space,
like visible light, and the utmost pos
Sible transmission distance would be
to just beyond the horizon.
The shorter the waves, the more
easily they pass through the rejecting
layers. These layers vary greatly in
thickness and continuity with the
amount Of sunlight, the season, and
various other factors. They tend to
become quite tenuouS, sometimes nom
existent at night, especially in winter.
when short-wave transmission beyond
the horizon is quite unreliable.
Leave Electrical Trails,
Now, DR.. Willard points out. there is
which is electrified by an entirely diff
ferent means-the electrical trails left
by shooting stars burning due to, fric-
ton with the atmosphere. Unlike the
electriflcation caused by sunlight, this
does not change appreciably with sea-
son or time of day. If anything. 1t Is
at its best during winter night. The
number of meteorS arriving from outer
space is approximately constant The
average relative size is about that Of a
grain Of sand. They pass with the
speed Of rifle bullets through the ex-
treme upper atmosphere, which is so
thin as to be essentially non-existent.
At an altitude of about 70 miles, how
ever, the air becomes thick enough to
produce an appreciable friction. The
meteors become incandescent and leave
ionized. or electrical trails, as they are
reduced to fine ash.
Very few-on the average night q
maximum of eight or ten an hour
are visible as shooting stars. Actually
the numbers are almost uncountable.
This has been, revealed strikingly by
radar echoes during the past few years.
Work carried on especially at the Bu-
reau of Standards and by British in
vestigators has shown great showers
Of these tiny objects during daylight
hours when it would be impossible to
see any of them. The radar echoes
come directly back to the receiver at
the point from which they are sent.
Reflect at Angle C.
1t is now found, DR.. Willard says,
that an appreciable amount of the
short-wave energy is reflected back to
the earth at geonletrical angle, just
as they are reflected from electrified
layers produced by the sun. All that
is necessary is that they be sent out
at the proper angles and at the right
frequencieS.
THUS 1t appears" he believes. "that
many thousands of tiny meteors which
lombard the earth's atmosphere at all
times are about to be put to a prac-
tical use-that of providing a reliable
method of communication over dis
tances OF the order of 1000 miles. BY
taking advantage of the dispersive prop
critics Of ionized layers, in addition to
their well-known reflecting properties,
the capacity of the now overloaded
high-frequency spectrum can be greatly
extended. Many channels now silent for
so many hours of the day and year
will at last be made to work around
the clock"