ZIERIA is the galaxy's only commercially viable source of zieron, a toxic gas with multiple industrial and military applications.  Because Zieria is collectively owned, all of its citizens share equally in the profits from the zieron wells, which are decades old at a minimum.  Enthusiasm for drilling new wells has diminished, but the old ones are still productive enough to sustain the planet's small population.  Currently the most severe punishment for crime on Zieria is well maintenance duty, which involves confinement to a hut full of machinery.  Once there, a prisoner has a fairly strong incentive to do a good job preventing zieron leaks.  If for some reason the prisoner's efforts are insufficient, though, there's nothing more that can be done except to send in another conscript who was unfortunate enough to be convicted of a crime.  Justice works swiftly on Zieria, but its effectiveness leaves considerable room for improvement.  There is a lot of poisonous zieron floating around.