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Aviation History
1957
1957 - 1796.PDF
886 FLIGHT Rockets for Research SCIENTIFIC EXPLORATION ON THE FRINGE OF SPACE IN an issue of Flight devoted largely to recording the efforts ofmany countries to produce bigger, faster and more lethalmeans of airborne destruction, it is perhaps a refreshing change to consider some of the ways in which rockets and missilescan perform useful contributions to basic scientific knowledge on an international scale. With the International Geophysical Yearprogramme in the background—and two orbiting Earth satellites very much in focus in the foreground—there is much of greatinterest to report in the field of research into the upper air. The subject is wide and fascinating. It is simply explorationinto the realm of space. The purpose of this exploration, for those who wish purposes to be stated, is to extend our basic scientificknowledge—to sound out the upper air. A sounding rocket blasts up to one hundred miles and telemeters data back for a few briefminutes: yesterday we used a lump of lead on a length of twine, swung outboard to sound the ocean-bed. The sea is now familiar,but the upper air is not. We need to chart the upper air for a variety of reasons—simplyto understand its structure better, to provide data for future manned interplanetary flight and, strangely perhaps, to find outmore about our own planet Earth; its weather, its magnetism, and even its shape. The scope is wide, and this article cannot hope tocover the entire field in detail. We shall hope to indicate generally the kind of information that is sought and is provided by rocketsand satellites, and to give examples of particular projects. Temperature, density and pressure are obvious and basic proper-ties to be measured directly, and it is only with rocket-borne equipment that a detailed knowledge of these properties at heightsabove the limit of balloon ascents has been obtained. The peak altitude of the majority of sounding rockets occurs intbe ionosphere, the "middle layer" of the atmosphere, which is an area of great interest. This region contains the ionised, or electric-ally charged D, E and F layers from which the reflection of ground radio signals has made possible very long-range trans-missions. Ground-based methods of investigating many aspects of the ionosphere are difficult, while rocket sounding can providemuch information. Two most important subjects of study which demand high-altitude measurement are solar activity and cosmic radiation. A note of these two areas of investigation is included in the laterreferences to Russian and U.S. satellite work. While the sounding- rocket technique gives good results in the study of the verticalvariation of a quantity at a certain place and time, its limitations are the short duration (at most a few minutes) during whichmeasurements can be made, and the fact that variations with time cannot be measured. Night airglow can also be studied, using rocket-borne photo-meters. Other phenomena capable of investigation by rockets are the dynamo currents responsible for the quiet magnetic variations;disturbed magnetic variations (magnetic storms); and the extent and nature of the auroral zones. Among other rocket experiments being carried out at presentare the location of the optical horizon; determination of the dis- tribution of ozone in the upper atmosphere; determination ofultra-violet fluorescences of upper atmosphere during auroras; measurement of the Earth's magnetic field, with such measure-ments used to locate ionospheric and auroral current flows; and the measurement of low-energy cosmic rays as a function ofgeomagnetic latitude, and correlation of intensity fluctuation with solar and magnetic phenomena. For the extra expenditure of rocket power (and of accuratecontrol) sufficient to establish a satellite in orbit, a great deal more information can be obtained than with any sounding rocket.Firstly, the satellite can carry its own measuring instruments and can telemeter the results to the ground until the batteries poweringits transmitters run down. Secondly, ordinary continuous-wave radio signals from a satellite which, in an elliptical orbit, dips intothe ionosphere to its perigree and out again to an apogee at 500- International Geophysical Year experiments include the establish- ment of Vanguard satellites in orbit by the U.S.A., and firings of Sky- lark upper-atmosphere rockets by Britain. The U.S. satellite programme was preceded by the recent test launching of the three-stage Vanguard rocket (left) at Cape Canaveral, Florida; the heading photograph shows a Skylark launch at Woomera, South Australia.
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