Build and fly a photodiode-based sun sensor to validate attitude determination algorithms. Compare on-orbit measurements against simulation predictions and the onboard ADCS to calibrate pointing accuracy.
Build and fly a photodiode-based sun sensor to validate attitude determination algorithms. Compare on-orbit measurements against simulation predictions and the onboard ADCS to calibrate pointing accuracy.
This is a beginner-level project with an estimated timeline of 8-12 months using a 0.5U form factor.
Knowing where the Sun is relative to your satellite is one of the most basic and important measurements in spacecraft operations. Sun sensors feed into attitude determination algorithms, trigger power management decisions, and help protect sensitive instruments from direct solar exposure. Commercial sun sensors are expensive, but building one from photodiodes and basic electronics is a well-documented educational exercise that teaches analog circuit design, calibration methodology, and sensor fusion. This project mounts photodiode sensors on multiple faces of the satellite and uses the relative current readings to compute a sun direction vector. A secondary experiment adds a pinhole camera approach for higher-accuracy determination. The real value comes from comparing the student-built sensor against the satellite platform's built-in attitude estimate quantifying accuracy, noise characteristics, and response time under actual orbital conditions including rapid transitions between sunlight and eclipse. This is an excellent first project for teams new to satellite hardware, since the electronics are simple, the physics is intuitive, and the results are immediately useful for validating the satellite's attitude knowledge.
6x SFH 2430 photodiodes (~$3 each) mounted on each face of the payload module, plus pinhole CMOS camera (OV7670, ~$10) on one face for fine sun vector determination. Photodiode outputs through transimpedance amplifiers (OPA330, ~$2 each) to ADC inputs on payload MCU. Calibration: known light source at measured angles in dark room. Flight software: compute sun vector from 6-face current ratios, compare against PyCubed onboard ADCS estimate. Log pointing error statistics over multiple orbits.
University of Prince Edward Island SpudNik-1 achieved 0.09° accuracy with pinhole camera sun sensor demonstrates what is achievable with simple hardware. Photodiode-based coarse sun sensors are standard on nearly every CubeSat this experiment adds value by precisely characterizing accuracy and comparing multiple approaches (photodiode array vs pinhole camera). Pairs well with PyCubed ADCS subsystem as calibration reference. Teaches analog electronics design (transimpedance amplifiers, ADC calibration). Cost: $50-$300. Complexity: low-to-medium. Good first-year introductory project.
This project spans 2 disciplines, making it suitable for interdisciplinary student teams.
Ready to take on this project? Here's a general roadmap that applies to most CubeSat missions:
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