arXiv (Cornell University) · 2017 · 26 citations · 0 references
EngineeringAerospace EngineeringAstronomyOrbital MechanicsSpacecraft DesignX-ray AstronomyAttitude DeterminationOrbit DeterminationSolar X-ray AstronomyX-ray OpticsOn-orbit Pointing AccuracyPointing AccuracyPointing SystemsSolar Soft X-ray EmissionSolar X-ray InstrumentationSolar X-ray ObservationsSpacecraft PointingSpacecraft Pointing Accuracy
The Miniature X-ray Solar Spectrometer (MinXSS) is a 3 Unit (3U) CubeSat\ndesigned for a 3-month mission to study solar soft X-ray spectral irradiance.\nThe first of the two flight models was deployed from the International Space\nStation in 2016 May and operated for one year before its natural deorbiting.\nThis was the first flight of the Blue Canyon Technologies XACT 3-axis attitude\ndetermination and control system -- a commercially available, high-precision\npointing system. We characterized the performance of the pointing system on\norbit including performance at low altitudes where drag torque builds up. We\nfound that the pointing accuracy was 0.0042\\degree\\ - 0.0117\\degree\\ (15$''$ -\n42$''$, 3$\\sigma$, axis dependent) consistently from 190 km - 410 km, slightly\nbetter than the specification sheet states. Peak-to-peak jitter was estimated\nto be 0.0073\\degree\\ (10 s$^{-1}$) - 0.0183\\degree\\ (10 s$^{-1}$) (26$''$ (10\ns$^{-1}$) - 66$''$ (10 s$^{-1}$), 3$\\sigma$). The system was capable of dumping\nmomentum until an altitude of 185 km. We found small amounts of sensor\ndegradation in the star tracker and coarse sun sensor. Our mission profile did\nnot require high-agility maneuvers so we are unable to characterize this\nmetric. Without a GPS receiver, it was necessary to periodically upload\nephemeris information to update the orbit propagation model and maintain\npointing. At 400 km, these uploads were required once every other week. At\n$\\sim$270 km, they were required every day. We also characterized the power\nperformance of our electric power system, which includes a novel pseudo-peak\npower tracker -- a resistor that limited the current draw from the battery on\nthe solar panels. With 19 30\\% efficient solar cells and an 8 W system load,\nthe power balance had 65\\% of margin on orbit. We present several\nrecommendations to other CubeSat programs throughout.\n