So far we have considered what might be called the “pure” rather than
the “applied” side of the study of meteorites. The investigator in any
pure science asks of a new discovery, “What does this tell me about the
universe? How does it better help me to understand the laws of nature?”
Of the same discovery, however, the worker in an applied science will
ask, “What practical use can be made of this gain in knowledge? What can
it be made to do for mankind in general?”
These questions reveal a decided difference in viewpoint, but this
difference does not reflect unfavorably on either class of scientists.
In fact, there is a great deal of truth in the saying “Today’s pure
science is tomorrow’s applied.” Actually, ways and means of taking
advantage of seemingly useless scientific discoveries are constantly
being found. The most famous example of this principle is the
development of the atomic bomb from the results of Einstein’s researches
in the abstract field of relativity. Here the seemingly mystic formula E
= mc² came to have far-reaching practical applications indeed!
Meteoritics has some exceedingly practical applications. Far from being
completely “out of this world”—as the recovered meteorites themselves
originally were—this science has been and can be made to serve mankind
in a number of rather unexpected ways. Meteoritics, the onetime
“stepchild of astronomy,” is currently being regarded with
ever-increasing respect by scientists and engineers working in many
different fields.
Consider, first of all, the stainless steels that are so widely used in
modern industry, and even the fine satin-sheen stainless “silverware”
that graces our dining tables. These have wisely been patterned after a
natural alloy with lasting qualities of strength, tenacity, and
resistance to corrosion. This natural alloy is the one making up the
iron meteorites.
Its toughness and durability became well known wherever attempts were
made to section these metallic meteorites. Specially designed and
extra-powerful sawing equipment is required to slice meteoritic iron,
and even with it, progress is painfully slow. So astounded were those
who first tried to cut iron meteorites with ordinary metal saws that one
of the earliest practical results was the development of battleship
armor plate composed of a commercial alloy called “meteor steel,” which
mimicked the composition of the iron meteorites.
Of course, a good deal of the difficulty of sectioning meteorites arises
from the fact that those doing the cutting are trying hard not to waste
valuable meteoritic material. Every precaution is taken to keep the
amount of “sawdust” to a minimum, for such finely ground up and
contaminated meteoritic material is of little scientific use. And, in
addition, scientists must guard against heating meteorites to high
temperatures because such heating destroys the delicate internal
structure of the masses. If these two considerations (loss of material
and overheating) were unimportant, even a large meteorite could easily
be divided up by use of such high-powered oxyacetylene torches as are
used to dissect huge obsolete battleships.
At the Institute of Meteoritics, a thin, water-cooled blade of soft iron
is driven slowly back and forth by an electric motor. Carborundum grit
in water suspension is fed evenly into the narrow cut over its entire
length. This grit becomes imbedded in the lower edge of the soft iron
blade, which then acts as a “many-toothed” metal saw. Several meteorites
can be sectioned simultaneously by this multiblade saw. In the future,
such newly developed methods as high-speed particle jet streams or
ultrasonic devices may be used to section meteorites both rapidly and
economically.
In the field of cosmic ray studies, particularly those concerned with
the protection of space travelers from harmful radiation, meteoritics
can be of help. The recovered meteorites have already come through those
regions that would be crossed by even the farthest-ranging spaceships.
Consequently, a great deal can be learned from the study of meteorites
about the intensity of the cosmic radiation that the crews of such ships
must face once they get outside the earth’s protective air-shield.
The first study of this type was made in May, 1948, at the Institute for
Nuclear Studies of the University of Chicago (now the Enrico Fermi
Institute). Scientists made radioactivity tests on samples of the Norton
County meteorite donated for this purpose by the Institute of
Meteoritics and air-expressed to Chicago because of the intense interest
in the radioactivity question. In October, 1949, English investigators
ran similar tests at the Londonderry Laboratory for Radiochemistry,
Durham, England, on samples of the freshly fallen Beddgelert, North
Wales, meteorite discussed on pp. 69-70. The results of these two
pioneer studies were negative because the “Model-T” instruments
available in 1948 and 1949 were not sensitive enough to detect the
relatively low radioactivities present.
[Illustration: The 6-blade meteorite gang-saw in the machine shop at
the Institute of Meteoritics.]
In 1955, however, scientists at Purdue University, using more refined
counters, studied small nuggets of nickel-iron, also from the Norton
meteorite. This time, the results of the radioactivity tests were
positive. The investigators detected tritium (an isotope of hydrogen
produced by cosmic-ray bombardment) in the samples. Furthermore, the
_amount_ of this rare isotope present indicated that the intensity of
cosmic radiation outside the earth’s atmosphere may be very much higher
than had previously been thought possible. “Forewarned is forearmed,”
and from the standpoint of future astronauts, this is as practical a
result as one could wish for!
In the relatively near future, men will certainly land on the surface of
the moon. We know from radiometric studies that some degree of
radioactivity is induced in meteorites by the full-intensity cosmic
radiation to which they have been exposed during their motion through
space. The nearly airless moon, like the meteorites, has also been
exposed to very intense cosmic radiation for a long time. So those who
are planning to land on our satellite are concerned about the
radioactivities they will encounter when they begin their explorations
of the lunar surface.
Suppose that extra-sensitive instruments were designed to pick up and
measure the radioactivities. Suppose further that these instruments were
mounted in a space-probe put in an orbit circling closely about the
moon. Plans for such a project are now under way. What types and
intensities of lunar radioactivities might such probe-mounted
instruments record?
Until such a space-probe becomes available, earth-bound space-scientists
are seeking at least a preliminary answer to this question. They are
doing this by investigating the natural “probes” that have come to us
from space—the meteorites.
Investigators have undertaken such studies very recently by employing a
new radiometric method technically called _gamma-ray spectroscopy_. Work
of this sort has been and is being done at the Los Alamos, New Mexico,
Scientific Laboratory on scores of meteorite and tektite specimens
loaned to the Laboratory by the Institute of Meteoritics. Some of the
individual meteorite specimens tested weighed as much as 37 pounds, and
are probably the largest single extra-terrestrial masses yet tested for
cosmic ray-induced radioactivities.
Let us turn now to another important application of meteoritics. Any
body in motion through the air or in space has a “striking power” of
sorts. For some objects, this striking power, which is technically known
as _ballistic potential_, is very weak, as in the case of silky
milkweed-down drifting through the air. Hailstones have a good deal more
striking power, as may have been painfully demonstrated on your own
head. And, finally, such masses as falling meteorites (and especially
those orbiting in space, unretarded by atmospheric resistance) have an
extraordinarily formidable ballistic potential. This is because
meteorites are not only tough and dense, as good projectiles must be,
but are also moving at high velocities—particularly high if the
meteorites come into the Solar System from interstellar space.
For this reason, the speeds of meteorites are very important to
scientists responsible for rocket flights and for keeping satellites
aloft over long periods of time. Clearly, these men must have as
accurate information as possible on where and how fast meteoritic
particles are moving, so as to chart the safest routes for spaceships,
and to develop satisfactory means of protecting rockets and satellites
against the effects of bombardment by the smaller meteorites. For these
“small-fry” cosmic missiles are so numerous that many of them are sure
to be encountered even in brief flights outside the earth’s atmosphere.
Such information might also prove valuable in the future to the crews of
spaceships on long flights into deep space. Such men may face the life
or death problem of taking successful “evasive action” against giant
meteorites that will seem like flying hills and mountains.
A strong parallelism exists between a meteorite fall and the re-entry of
a nose-cone or data-capsule into the atmosphere. To a considerable
extent, the difficult problems connected with the latter are being
attacked at present through careful studies of meteorites. From the
air-sculptured shapes of meteorites, their crustal flow patterns, and
the thicknesses and types of fusion crusts they show, scientists are
learning a great deal about certain factors connected with the re-entry
problem. These factors include rate of vaporization, effects of extreme
temperatures, and types of sculpturing to be expected as a result of
encountering the resisting molecules of the atmosphere.
[Illustration: Relationship between (A) the trajectory of a falling
meteorite, and (B) the re-entry stage of a V-2 rocket. The solid
lines indicate the similar portions of the two trajectories.
A. A METEORITE FALL
B. A V-2 RE-ENTRY]
One of the most obvious applications of meteoritics in the future will
grow out of the well-known fact that our earthly resources of many
strategic materials—especially metals like iron and nickel—are fast
becoming exhausted. The population of the earth is increasing at a mad
pace, and an end to metal-consuming wars is still not in sight. The need
for such metals can only become more and more acute.
According to one of the currently favored explanations of the origin of
the meteorites, the core-fragments of the parent meteorite-planet are
solid masses of nickel-iron alloy—like the mass that blasted out the
Canyon Diablo meteorite crater. If this meteorite-planet hypothesis
finally wins general acceptance, the meteoriticist of the future is
almost sure to be set the task of pin-pointing as exactly as possible
the whereabouts in space and time of the most easily accessible cosmic
nickel-iron lodes of this sort. Once he has given an answer, the space
engineers will take over, and mining operations will be started on the
unlimited sources of essential metals to be found in outer space.
Initially, no doubt, metal recoveries will be freighted back to earth in
rocket-load lots. But as the need for iron and nickel increases on a
metal-hungry earth, vast engineering projects may well be undertaken to
“snare” the larger metal meteorites and equip them with rocket motors.
This will be done so that by use of rocket power, the natural orbits of
the meteorites can be changed into orbits bringing them back to earth.
Unlike the natural, uncontrolled Canyon Diablo meteorite fall that
vaporized what would have been a rich nickel-iron deposit, the
rocket-controlled meteoritic “metal mines” will be eased down to earth
all in one piece.
Reading of the possibility of sending out expeditions to find large iron
meteorites in the depths of space may bring to your mind an image of the
fearless mariners of old who sailed their stout ships over dangerous,
often uncharted seas in search of the great whales. The rocket crews of
day-after-tomorrow will no doubt be equally fearless and resourceful as
they navigate the sea of space, intent on capturing the great “metal
mines” of the future.
The experience gained in such space-mining ventures will then be carried
over into expeditions to ensnare the larger stony-iron meteorites. These
masses of iron and stone will offer less favorable mining possibilities,
but they can be turned into rocket-propelled and guided de luxe
space-cruisers. By this term, we do not mean that these natural
space-ships will house all the luxuries of the ocean-liners advertised
in the travel magazines. Rather, we see them as providing roomy,
comfortable “underground” living quarters. Furthermore, their occupants
will be adequately protected by great thicknesses of metal and rock from
the injurious radiations of empty space, and the meteorites that make
the term “empty space” something of a misnomer.
Initially, such worlds-in-miniature will be much sought after as
laboratory sites where the more violent and dangerous of the many
experimental tests which venturesome man will wish to conduct can be
carried on without danger to the close-packed billions populating the
then-crowded earth.
Later on, these meteorites-turned-into-space-ships may be used to
explore the dangerous and faraway corners of the Solar System, since the
very substance of each massive meteoritic rocket-body will serve as an
adequate and handy source of fuel supply.
When men have learned to live on such “homes away from home,” it is
quite possible that the larger of these modified meteorites, after their
interiors have been opened up for occupancy by the inroads of the
fuel-hungry rocket-motors, may be steered into neighborly orbits about
old Mother Earth. Here, these “natural” satellites will assume the
unexciting but necessary roles of the extra living quarters that by then
will be so urgently needed to accommodate the mushrooming population of
the world of the future.
People who live in these super-urban outliers of Mother Earth may take
the same pride in their natural, if converted, homes as many former city
dwellers now take in the old-fashioned sprawling farmhouses they have
rebuilt and occupied. Perhaps one of your descendants will live in such
a meteorite-orb, and occasionally point the finger of scorn at the more
elegant but unpleasantly overcrowded artificial satellites preferred by
those migrants from teeming earth who lack the true pioneering instinct.
Who knows!