Applied Research and Development for Falling-Sphere Air Density Measuring Systems

摘要

This contract involves the development, fabrication, testing, and calibration of four complete high altitude densitometer payloads, each comprised of a nose cone, an ejection system, and a ten-inch falling sphere. The sphere, in turn, is instrumented with a sensitive accelerometer, a TM system, a nutation sensor, and various ancillary power supply and control systems. Air density is determined by measuring the negative air-drag acceleration as experienced by the sphere as it falls through the atmosphere. By evaluating the air drag equation for a spherical shape having the same area and mass, with the measured fall velocity and negative acceleration the air density profile for the trajectory can be calculated. Air density measurement over the desired range of 50 to 150 KM requires the use of a sensitive accelerometer having a dynamic range of 0.01 to 0.0000001 g's. Four complete falling-sphere densitometer systems were designed, fabricated and launched at four locations: Wallops Island, VA; Kiruna, Sweden; Poker Flat, Alas.; and Andoya, Norway. The former back-up densitometer was upgraded and was flown during the Norway program. Three unique support units were designed and fabricated for use with the European payloads. A solar aspect system was designed, fabricated and flown on the Alaskan payload. Additionally, several studies were performed to generally improve the ground and flight equipment.