Short answers, pulled from the story.
PROCYON launched on the 3rd of December 2014 at 13:22:04 Japan Standard Time as a secondary payload alongside the Hayabusa2 asteroid probe. Its mission was to perform a close flyby of an asteroid, passing within 30 kilometres of the target, using optical navigation techniques. The asteroid flyby was planned for 2016 but was abandoned after the ion thruster failed.
The ion engine failed on the 10th of March 2015 and could not be restarted. Without propulsion, PROCYON could not perform the controlled orbit change needed to reach its asteroid target. The spacecraft flew past Earth on the 3rd of December 2015 but lost contact with ground controllers shortly afterward.
PROCYON was developed by the University of Tokyo and JAXA, the Japan Aerospace Exploration Agency. It was a small, low-cost spacecraft measuring approximately 60 centimetres on a side and weighing 70 kilograms.
PROCYON captured the first complete image of Earth's geocorona, confirming for the first time that it has north-south symmetry. The spacecraft also observed the Lyman-alpha emission of comet 67P/Churyumov-Gerasimenko to determine the overall structure of the comet's coma.
When first started on the 22nd of February 2015, PROCYON's ion engine delivered 330 micronewtons of thrust, exceeding its designed output of 250 micronewtons. Despite this early overperformance, the engine failed permanently on the 10th of March 2015.
PROCYON used an ion engine for main propulsion and eight cold-gas attitude-control thrusters, all fed from a single shared xenon tank holding 2.5 kilograms of propellant at launch. The spacecraft had a specific impulse of 1000 seconds and a delta-v budget of about 500 metres per second.