Atmospheric life studies outside the area of cosmic radiation effects have been comparatively few. Results from two manned flights, Strato-Lab I and II, indicate that the flights did produce pronounced changes in white blood cell count; however, the data suggest that these changes were due to psychological rather than physical stress. Exposure to altitudes above 90 000 feet for a total of 62 hours did not produce any general behavioral change in two Java monkeys, according to other balloon flights. Many of these flights were effective in testing equipment, telemetering devices, and in pointing the way for other flights.
Stratoscope I and II, originally undertaken by the Office of Naval Research (ONR), are projects involving various astronomical observations with the aid of a balloon-borne telescope and television and camera systems. NASA cooperated with ONR on Stratoscope II (36-inch telescope compared with Stratoscope I's 12-inch telescope) which has already resulted in significant discoveries about the nature of the planets and stars. Water vapor has been identified in the atmosphere of cool red stars and an analysis of the Martian spectra showed a greater abundance of carbon dioxide than had previously been believed. Since the balloon-borne telescope was carried beyond Earth's obscuring atmosphere, the Stratoscope projects have yielded valuable photographs of the Sun, stars, and various planets.
ROCKETS AND SATELLITES
Historically, biological experiments aboard rockets and satellites have been limited to a "piggyback" and "noninterference" basis on military rockets. For the past few years, however, as the effort toward manned space flight leading to lunar and Martian landings increased, more attention was devoted to experiments designed to show the effects of the space environment on living systems. As in the balloon flight programs, the U.S. Army, Navy, and Air Force played an important role, reaching what might be considered a high point with the successful launch and recovery of a ballistic rocket experiment with monkeys Able and Baker. Aerobee rockets as well as Thor IRBM's carried biological payloads consisting of mice and monkeys on six launches, contributing to our knowledge of the effects of weightlessness and radiation on higher animals.
Van der Wal and Young ([ref.78]) used Thor-Able combinations to serve as boosters for lifting a 20-pound biocapsule to a peak altitude of 1400 miles and over a distance of about 5300 miles from Cape Canaveral to the west coast of Africa. Weightlessness was attained for a period of almost 40 minutes. During reentry into the atmosphere, a peak deceleration of about 60 g was reached. Each of the three capsules flown carried one mouse (Mouse-in-Able); two of the mice were instrumented for heart-rate telemetry. Although all three mice were lost, the two experiments with Laska and Benji yielded physiological results.
The experimenters designed effective instrumentation for registering the electrical activity of the mouse's heart through a single commutated telemetry channel. Records were obtained for both animals during various portions of the flight. The results indicate that both animals were alive when the nose cones hit the water.
Two South American squirrel monkeys (Gordo and Baker) and a rhesus monkey (Able) were launched into space from Cape Canaveral in 1958 and 1959 by U.S. Army Jupiter missiles. The vehicles reached speeds of approximately 10 000 mph and altitudes of 300 miles on flights which lasted about 15 min.
Time courses of cardiac and respiratory rates ([ref.80]) of the two squirrel monkeys showed that the noise of the engine at liftoff immediately produced an increase in their heart rates. Respiration also increased temporarily, but slowed later with increasing acceleration. Heart rates fluctuated considerably during launch acceleration, which reached about 15 g at cutoff.
The period of free flight and weightlessness was characterized by pronounced fluctuations of heart activity in the postacceleration phase. Thereafter, the heart rate of Baker remained relatively constant, whereas the cardiac activity of Gordo fluctuated markedly and decreased slowly almost to the end of his flight. Slight changes, which were transient and not pathological in nature, were also noted in the electrocardiogram. Gordo's respiration was very shallow during maximum launch acceleration, when Baker's reached its highest value, only to be approximated again during reentry when forces of about 35 g were encountered.
Able's cardiac and respiratory rates indicated that, after an initial startle reaction, the heart rate dropped transiently and then increased steeply, reaching a maximum of 259 during the 10-second interval at peak acceleration. Respiration increased only slightly throughout the launching phase. There was a period of tachycardia during postacceleration weightlessness, after which the heart rate declined steadily and was disturbed only by several startling missile events. At the end of the subgravity phase, Able's cardiac rate was slightly below normal.