From sky to screen: improving file downlinking over error-prone, omni-directional links from the stratosphere

Abstract

Long-duration stratospheric balloon missions must transmit large volumes of scientific and telemetry data over variable, omni-directional links that are prone to packet loss and bandwidth fluctuations. To address this, we developed a semi-autonomous file-downlink system for high-altitude astronomy missions such as SuperBIT and its successor, GigaBIT. The system comprises a payload client, a ground server, and a cleaner program capable of operating across both UDP and TCP links. The client manages a dynamic queue of data products and divides them into fixed-size chunks with metadata, enabling resumable transfers and selective retransmissions. This chunk-level approach ensures that only corrupted or missing data is resent, reducing bandwidth usage. The system increases overall throughput and substantially improves telemetry downlink on the constrained links typical of stratospheric telescope missions. This paper presents the system design and protocol behaviour in detail, situates it within SuperBIT’s broader communications architecture, reports its performance during SuperBIT’s final flight, and introduces parachuter, an open-source reimplementation released so that future missions can adopt and extend the approach.