SAIL students have been launching high-altitude balloons since 2008. The balloons reach an average altitude of 32 km (105,000 feet). The standard payload includes a pressure sensor, temperature sensor, nine degrees of freedom sensor, GPS, radio and housekeeping sensors along with the CPU board and a battery-based power supply. The payload is tracked autonomously by a ground station high-gain antenna based on telemetry received.
SAIL is part of a 2017 funded AFOSR MURI project named HYFLITS. This is a five-year effort to resolve significant operational issues concerning hypersonic vehicle aerothermodynamics, boundary layer stability and aero-optical propagation. In-situ turbulence measurements, along with modeling, will quantify spatiotemporal statistics and the dependence of stratospheric turbulence on underlying meteorology to a degree not previously possible. The lead institution is the University of Colorado Boulder, with participation from the University of Minnesota and Embry‑Riddle Aeronautical University.
Data from high altitude balloons (HAB) sampling at 1-2 kHz is required to characterize turbulence to the inner scale, or smaller, over altitudes from 20 km to 35+ km. SAIL is developing strategies to increase the reliability of conventional latex balloons to consistently achieve altitudes of about 35 km (115,000 feet) as well as offer controlled descent enabling unperturbed environmental measurements on the downleg while using as much as possible commercial, off-the-shelf (COTS) components.
A field deployable ground station using Yaesu G5500 rotor tracks the balloons autonomously based on GPS coordinates received in the telemetry. The ground station GUI shows the predicted path versus the actual path, some housekeeping sensor data, as well as the balloon's instantaneous azimuth and elevation. A poster on this effort was recently presented at the Fall 2018 AGU meeting. This poster can be downloaded online. We have so far successfully tracked the balloon up to a range of 167 km and a max downlink data throughput of 100 kbps.
