We investigate the transient nature of water plume deposits on Europa's surface, focusing on how radiolysis and ion sputtering (Europa's two most effective erosion processes) affect their lifetime. Our study is motivated by the lack of observed surface changes in imaging data, despite tentative plume detections, and aims to inform future missions, such as JUICE and Europa Clipper, about expected timescales of deposit survival to optimise their observational strategies. We present two models that simulate a first order estimate of the erosion time of deposits formed by water plumes considering a wide range of mass flux and eruption duration. Model 1 considers a confined (10 km) deposit near the source, while Model 2 evaluates the erosion material deposited 25 km from the plume source to match observation limitations in other studies. Our results show that plume deposits are short lived relative to Europa's average surface age for a wide range of mass fluxes and eruption times. Even intense plumes with 10, 000~kg/s mass fluxes produce deposits that erode within 10~Ma. For plumes such as the one observed by HST in 2012, deposits may be removed within years to decades. Erosion rates vary significantly with location, with polar regions offering the best conditions for long-term preservation. These findings support the hypothesis that the absence of visible deposits in current data may be due to rapid erosion rather than a lack of activity. They highlight the importance of time sensitive and geographically targeted observations for maximising the scientific output of upcoming missions.
Anarte et al. (2025) studied this question.