This paper presents the design, development, and pre-launch characterization of the ESTCube-1 Attitude Determination and Control System (ADCS). The design driver for the ADCS has been the mission requirement to spin up the satellite to 360 deg·s −1 with controlled orientation of the spin axis and to acquire the angular velocity and the attitude during the scientific experiment. ESTCube-1 is a one-unit CubeSat launched on 7 May 2013, 2:06 UTC on board the Vega VV02 rocket. Its primary mission is to measure the Coulomb drag force exerted by a natural plasma stream on a charged tether and, therefore, to perform the basic proof of concept measurement and technology demonstration of electric solar wind sail technology. The attitude determination system uses three-axis magnetometers, three-axis gyroscopic sensors, and two-axis Sun sensors, a Sun sensor on each side of the satellite. While commercial off-the-shelf components are used for magnetometers and gyroscopic sensors, Sun sensors are custombuilt based on analogue one-dimensional position sensitive detectors. The attitude of the satellite is estimated on board using an Unscented Kalman Filter. An ARM 32-bit processor is used for ADCS calculations. Three electromagnetic coils are used for attitude control. The system is characterized through tests and simulations. Results include mass and power budgets, estimated uncertainties as well as attitude determination and control performance. The system fulfils all mission requirements.

This paper presents the characterization and in-orbit validation of the ESTCube-1 attitude determination system (ADS). ESTCube-1 is a one-unit CubeSat built by students and launched on May 7, 2013 to a Sun-synchronous, 700 km, polar low Earth orbit. Its primary mission is to centrifugally deploy a tether as a part of the first in-orbit demonstration of electric solar wind sail (E-sail) technology. The ADS uses magnetometers, gyroscopic sensors, Sun sensors and an Unscented Kalman Filter for attitude determination. Here we share the performance of commercial off-the-shelf (COTS) sensors and results from tuning the system-re-calibration, software and Kalman Filter adjustments. We validate the system by comparing the attitude determined by the on-board ADS with the attitude determined from on-board camera images. Uncertainty budgets for both attitude determination methods are estimated. The expanded uncertainty of comparison (95% confidence level, k=2) is 1.75 • and the maximum difference between attitudes determined by both methods is 1.43 • .

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