NIGHT CREW LABS
September 2021 – NCL developed a GNSS-RO prototype sensor for NASA’s DC-8 aircraft as it embarked on a multi-week flight campaign based in the US Virgin Islands. The purpose of this effort was to demonstrate a miniature sensor can be widely deployed on commercial aircraft, and use its GPS data to characterize Earth’s atmosphere and thus improve overall global forecasting models.
Mission
NCL developed the Aircraft In-situ and Radio Occultation (AIRO) instrument. The goal of AIRO was to miniaturize a GNSS-RO payload for aircraft applications. In our previous work, we showed that commercial-off-the-shelf GNSS receivers proved highly capable in producing data of sufficient quality for RO vertical profile retrieval.
To fly as a hosted payload on NASA’s DC-8 aircraft, our instrument needed to fit in a 6U volume (30 cm x 20 cm x 10 cm), which then was mounted within a rack mount. To fit within the size constraint while packing as much instrumentation as we could, we made a few mods. We used one of the latest Septentrio receivers and built an electrical/mechanical interface to a Raspberry Pi 4 computer to minimize its volume. We also made a custom power/data board which allowed AIRO to receive aircraft power as well as access to realtime sensor data (including GPS). AIRO used a single GNSS antenna installed on the top of the DC-8, and split that signal to several boards.
Results
In September, the DC-8 flew periodically for several weeks from St. Croix, US Virgin Islands. AIRO could only collect quality GNSS-RO data during straight-and-level flight. Because of its primary mission to analyze aerosols, the flight paths were sometimes erratic and didn’t follow a standard straight-and-level path. We were still able to collect a fair amount of data, and even picked up some interesting data while Hurricane Ida was developing in the Caribbean sea.
Results from this mission were published at ION GNSS+ 2021. You can read the publication here.
Thanks to NASA Flight Opportunities, and NASA Airborne for enabling this research!