ALOFT: GPS RO from Balloons

TECHNICAL ABSTRACT: The NOAA Integrated Earth System Process and Predictions 2018 Subtopic 8.1.1 “Radio Occultation from Recoverable Air Balloons for Weather Applications” solicitation has the goal of demonstrating the feasibility of a hardware/software system for a balloon platform that has sufficient quality for measuring global navigation satellite system (GNSS) signals to enable retrieval of atmospheric profiles such as temperature, moisture, and pressure through radio occultation. With the availability of low cost GPS receivers and maturing technology, there appear to be opportunities for measuring atmospheric profiles from recoverable air balloons, or even in conjunction with the radiosondes currently being launched. Therefore, this solicited project provides an opportunity for researchers to leverage previous GPS RO demonstrations from balloons to further demonstrate feasibility and pave the way for enhanced measurement capability and extensive commercialization of RO from air balloons. ASTRA will develop a compact GPS RO payload, ALOFT, that is compatible with high-altitude balloon platforms. We will also investigate ALOFT compatibility with radiosonde platforms. At development and launch costs an order of magnitude less than CubeSats, and with the ability for payload recovery, high altitude balloons have become a very economical means of making regional measurements from the upper atmosphere and space.SUMMARY OF ANTICIPATED RESULTS: The proposed Phase I effort will result in the development of a preliminary design of an ALOFT sensor system that meets the requirements of the solicitation. In Phase I, our team will conduct analysis to determine an optimal design sensing strategy that is compatible with high altitude balloon platforms. We will include a goal of ALOFT compatibility with a radiosonde as well. We will identify and complete trades on the critical engineering challenges. During Phase I we will establish a full set of design defining requirements against which performance is measured throughout the program lifecycle, and create system performance error budgets. Technical resource budgets will be used to identify and track size, mass, power, and telemetry capabilities. As part of our deliverable, we will provide a PDR package that includes detailed design and analysis of all ALOFT subsystems. Phase I will include data collection from a Colorado (near Boulder) high mountain top using a prototype system. Additionally, during Phase I, we will develop an economical and technically viable, manufacturable solution for ALOFT. This state of maturity at the end of Phase I will then enable us to transition quickly into Phase II where we will complete a Critical Design Review (CDR), and then fabricate, calibrate, and demonstrate a fully functional proto-flight ALOFT sensor system in a realistic environment, resulting in a TRL of 6 at the end of Phase II.