Meet the BEXUS team: SUNFLOWER

"Things didn’t always go as planned, but that’s where we truly learned the most. In SUNFLOWER, every challenge became a chance to grow together." SUNFLOWER Team 

SUNFLOWER is an experiment designed to validate the performance of two adaptive systems—Sunflower Light Cover (SLC) and Sunflower Thermal Cover (STC)—for maintaining optimal conditions of illumination and temperature inside a sealed chamber containing photosynthetic organisms. The project targets applications in bioregenerative life support systems, especially in orbit or on planetary surfaces, where resource efficiency is critical. The biological payload consists of a microalgae, Nannochloropsis, selected for their nutritional value and previous use in closed-loop systems. The aim is to verify if these organisms can maintain viability under stratospheric environmental stress, provided that internal chamber conditions are adequately controlled.

The payload consists of a cubic experimental box flown on the BEXUS 36 balloon, featuring a multilayer insulation system and two adaptive covers. The STC is mounted on an external radiating panel and modulates heat exchange with the environment. The SLC is mounted over a glass window and controls light flux into the chamber. Both covers use motorized “petals” that rotate to expose or shield surfaces. Internal light levels are monitored using spectrally selective photodiodes placed on a central cube (“the Flower”) above the biological sample, while temperature sensors track gradients near critical components. The system also includes active elements such as electric heaters and phosphorescent paint (SPP) for secondary lighting tests. During the flight, the experiment operates autonomously, following a predefined sequence of regulation and data acquisition phases.

The SUNFLOWER team consists of 13 students from the University of Padova, distributed across 7 technical subsystems: mechanics, thermal, electronics, software, biology, illumination control, and outreach. Team members come from various academic levels—bachelor’s and master’s students—in fields including aerospace engineering, biology, astronomy, data science, and computer engineering.

SUNFLOWER experiment in a nutshell