On the Use of Ionization Gage Devices at Very High Altitude

Abstract

T E M E A S U R E M E N T of atmospheric pressure, temperature and density, in regions of the high atmosphere where the mean free pa th of typical particles is long compared with the dimensions of the instrument , has interested upperair researchers for many years. Ear ly a t t e m p t s (1 to 4) using V-2 rockets were largely inconclusive because of ins t rument contamination by rocket gas or because the al t i tudes a t ta ined were insufficient. Some significant measurements to 120 km were made, bu t could not be considered as entirely fulfilling desired conditions of a long mean free pa th environment. No further significant measurements were made unti l the Viking rocket, and still later the Aerobee-Hi rocket, became available (5 to 9). The methods employed in these measurements have made use of local density determining devices which permit investigation of the pressure or density a t selected points on the surface of a rocket. This allows interpretat ion in terms of ambient conditions, provided there is knowledge of rocket velocity, al t i tude, air composition and other such factors. Advances in instrumentat ion, the availability of rockets with an increased capability for high alt i tudes, and the imminent availabili ty of satellite vehicles have stirred a compelling new interest in these measurement areas. Thus this paper considers the employment of ionizationtype devices for performing measurements of ambient pressure, temperature , density and in addition, composition, in the light of the newer developments.