Date of Award
Master of Science (MS)
Larsen , Miguel
Joseph , Paul
Passive falling spheres launched from small rockets have been used extensively in the past to measure the winds and densities in the mesosphere. In principle, the same technique can be extended to higher altitudes that cover the lower thermosphere, in addition to the mesosphere. The main difficulties are that accelerations decrease rapidly with height due to the decreasing atmospheric density and rigid spheres are required at higher altitudes, which implies larger mass and smaller accelerations. Accelerometers with broad dynamic range and high sensitivity are required for the measurements, but such devices are not readily available. We describe an instrumented falling sphere that consists of a lightweight, hollow sphere fitted with a high-sensitivity three-axis accelerometer in addition to other tracking and telemetry equipment. The sphere, along with an ejection system, is installed in the nose cone section of a sounding rocket. The sphere is ejected at an altitude near the base of the MLT (mesosphere and lower thermosphere) region (85-90 km) on the up-leg portion of the trajectory. The combination of the data from the up-leg and down-leg sections of the flight can be used to extract detailed density and neutral wind profiles. In addition, the temperature profile can be estimated by applying the hydrostatic equation to the density data.
Shah, Arpan, "DEVELOPMENT OF A FALLING SPHERE INSTRUMENT FOR HIGH-RESOLUTION NEUTRAL WIND MEASUREMENTS IN THE MESOSPHERE AND LOWER THERMOSPHERE" (2009). All Theses. 541.