SunbYte: A framework for low-cost robotic solar telescopes on high altitude balloons

Abstract The design and usability of a fully autonomous robotic control system (SunbYte-Sheffield University Nova Balloon Lifted Telescope) for solar tracking and observational applications on-board high-altitude balloons is addressed here. The design is based on a six step development plan balancing scientific objectives and practical engineering requirements. The high-altitude solar observational system includes low cost components such as a Cassegrain type telescope, stepper motors, harmonic drives, USB cameras and microprocessors. OpenCV installed from ROS, python and C software were used to collect and compress housekeeping/scientific data, process the signal, and transmit information to the ground-station via the launch vehicle telecommunication link. The SunbYte system allows the brightest spot in the sky to be identified, point towards it with high accuracy and capture that region with the main telescope. This paper gathers and presents the results from three missions: two flights with High-Altitude Student Platform (NASA Balloon Program office and LaSpace), and one flight with German-Swedish programme: REXUS/BEXUS. The system demonstrated the tracking capabilities of the Sun by capturing and analysing a series of tracking images with the location of the Sun at the calibrated centre. Housekeeping sensor data was collected which enabled issues with the thermal performance to be diagnosed. Low temperature reduced the responsiveness of the motor and harmonic drive actuation system. The developed ground-station interface and telecommunication link allowed response to in-flight issues through updates to the tracking parameters during the flight.