Europa is tidally locked to Jupiter meaning one side of Europa is always facing Jupiter (like our Moon). It also orbits in a nearly circular orbit however this

Europa is tidally locked to Jupiter meaning one side of Europa is always facing Jupiter (like our Moon). It also orbits in a nearly circular orbit however this is not to be confused with perfectly circular orbit: Europa will have perizene and apozene points (locations in which Europa is closest and farthest to Jupiter respectively) That being said we have made calculations based upon the tidal forces on Europa by Jupiter and the plumes seem to appear when Europa is at it's apozene location and disappear at its perizene location. I don't think it said in the article where Europa is. It could simply be nearing its perizene and the geysers go away due to the tidal model.