History of Research in Space Biology and Biodynamics
1. Important Technological Developments
[11] Many of the techniques developed during the pioneering period 1946-1952 in the use of both rockets and balloons for space biology research1, have continued to be useful in the later period of more intensive activity. Certain engineering techniques and methods of operation developed since then, however, have helped to make possible research accomplishments of far greater significance. Balloon operations from 1950 through 1952, for instance, provided a wealth of experience in balloon and capsule techniques, but only since 1953 have they amassed a significant quantity of data on such problems as the biological effects of cosmic rays.
The greater effectiveness of balloon flights from 1953 to the present has been partly the result of an increase in human and material resources devoted to the program. It also reflects the transfer of major launch operations to localities in the northern United States where, as now became apparent,2 the magnetic field of the earth converging on the poles permitted a much more significant exposure to primary cosmic radiation than at comparable balloon altitudes at the latitude of Holloman Air Force Base, New Mexico. Since the spring of 1953, in fact, space biology flights conducted at Holloman have been primarily to test balloon and capsule techniques or to expose biological control specimens to the relatively weaker radiation of lower geomagnetic latitudes. Finally, since 1953 there has been a sharp technical improvement in flight performance due in part to previous efforts only now beginning to bear fruit, and in part to continuing research and development by aeromedical scientists, balloon manufacturers, and others, both at Holloman and elsewhere.
One noteworthy development, first employed on space biology flights in 1953, was the perfection of radio command cutdown as a method of terminating balloon flights. Two different command cut-down devices were used in that year, one developed by the Aero Medical Laboratory at Wright Field and the other provided by the aeronautical laboratories of General Mills. This new method did not replace but came to supplement the earlier preset timer, which had been inadequate by itself because it might automatically let down a balloon capsule during a thunderstorm that would interfere with both radio and visual tracking, or perhaps drop an experimental cargo into the heart of an inaccessible area. At least now the flight could [12] be shortened if these difficulties were anticipated.3
Tracking and recovery techniques also improved steadily. Panel trucks equipped as radio monitoring and tracking stations supplemented the work of tracking aircraft. Improved balloon-borne antenna systems permitted an equipment package to send reliable signals even after it landed, thus helping search parties to find it. Any improvements in tracking and recovery were of course particularly important for space biology flights, which have always required prompter recovery than most. A lost balloon capsule might be returned months later, in response to the twenty-five-dollar reward notice posted on it, but by then all biological specimens would have perished.4
Since 1953, environment control for animal capsules has likewise undergone considerable improvement. One of the most ingenious developments was the use of boiling water as a coolant, a system pretested in the Standards Laboratory at Holloman and successfully flight-tested on balloon missions in the fall of 1953. The device is based on the principle that, because of decreased atmospheric pressure, water boils at lower temperatures when placed at higher elevations. At an altitude of about 112,000 feet, for example, water boils at thirty-two degrees Fahrenheit--the temperature where at sea level it would become solid ice. Therefore, water could be made to boil at high altitude simply by placing it in a container vented to the lower outside atmospheric pressure. When air within the sealed capsule was circulated around the container, vapor from the boiling water carried off heat from the capsule.5
Other improvements of equal or greater importance were steps taken to reduce the over-all weight of the capsules. During 1954 and 1955, the weight of the standard animal capsule was reduced from one hundred sixty-five pounds to about seventy. The direct result of this accomplishment is that identical balloon equipment can now attain significantly higher altitudes with the same biological specimens.6
Flight performance also benefited greatly from continued improvements in balloon launch techniques. At Holloman, the "covered wagon" technique, whereby a small or medium-size balloon could be protected during launch by inflating it on a vehicle with high headboard and nylon top, had been perfected and used during the pioneering years. Next came the shroud-inflation technique, which held the balloon beneath a large fabric cap during inflation. This system was later improved upon by using the crane-launch method, in which the delicate cargo is carefully suspended from the crane's boom while the balloon cell, at the opposite end of the load line, is undergoing inflation. And, by the close of 1957, these techniques were giving way to still other newly-devised methods.7
To be sure, these and other innovations in balloon techniques were not perfected solely for space biology flights. The Holloman Balloon Branch launched 683 plastic-type balloons in fiscal years 1951 through 1957, and only a small fraction of these were for cosmic radiation studies or other tasks of the Aeromedical Field Laboratory. The shroud-inflation technique, for instance, resulted from an effort of the Holloman unit to meet requirements for the manned balloon phase of Wright Air Development Center's Project 7218, Biophysics of Escape. Space biology studies, however, benefited from all major technological improvements, including those developed away from the Air Force Missile Development Center by private balloon technicians; and, in turn, the experience accumulated on flights for the Aeromedical Field Laboratory was of benefit to other balloon operations.8
Meanwhile, the balloons themselves were growing both bigger and better. One landmark was the introduction of the two-million-cubic-foot plastic balloons. The first of these to be used on a cosmic radiation flight was manufactured by Winzen Research, Incorporated, and launched 18 July 1955 at Fleming Field, South Saint Paul, Minnesota. It reached an altitude of over 120,000 feet. It was followed by a similar balloon launched the very next day which reached 126,000 feet, a record not only for the Aeromedical Field Laboratory program but also (to that date) for polyethylene balloons in general.9
Neither of these balloons was intended to set a flight-duration record, but time aloft on individual flights was also increasing steadily. This fact, plus the growing reliability of flight performance and recovery, permitted much longer exposure of individual specimens by reflying them on two or more consecutive flights. Because of greater uncertainties in recovery, capsule performance, and the like, this procedure of multiple flights was virtually impossible prior to 1953, but since that time it has become commonplace. In 1954, for example, test specimens were reflown on two separate flights for a total of seventy-four hours and thirty-five minutes at an altitude between 82,000 and 97,000 feet, mostly above 90,000.10