  The Miniature X-ray Solar Spectrometer (MinXSS) is a 3 Unit (3U) CubeSat
designed for a 3-month mission to study solar soft X-ray spectral irradiance.
The first of the two flight models was deployed from the International Space
Station in 2016 May and operated for one year before its natural deorbiting.
This was the first flight of the Blue Canyon Technologies XACT 3-axis attitude
determination and control system -- a commercially available, high-precision
pointing system. We characterized the performance of the pointing system on
orbit including performance at low altitudes where drag torque builds up. We
found that the pointing accuracy was 0.0042\degree\ - 0.0117\degree\ (15$''$ -
42$''$, 3$\sigma$, axis dependent) consistently from 190 km - 410 km, slightly
better than the specification sheet states. Peak-to-peak jitter was estimated
to be 0.0073\degree\ (10 s$^{-1}$) - 0.0183\degree\ (10 s$^{-1}$) (26$''$ (10
s$^{-1}$) - 66$''$ (10 s$^{-1}$), 3$\sigma$). The system was capable of dumping
momentum until an altitude of 185 km. We found small amounts of sensor
degradation in the star tracker and coarse sun sensor. Our mission profile did
not require high-agility maneuvers so we are unable to characterize this
metric. Without a GPS receiver, it was necessary to periodically upload
ephemeris information to update the orbit propagation model and maintain
pointing. At 400 km, these uploads were required once every other week. At
$\sim$270 km, they were required every day. We also characterized the power
performance of our electric power system, which includes a novel pseudo-peak
power tracker -- a resistor that limited the current draw from the battery on
the solar panels. With 19 30\% efficient solar cells and an 8 W system load,
the power balance had 65\% of margin on orbit. We present several
recommendations to other CubeSat programs throughout.
