ra0001">We predict the appearance of microscopic liquid water on Mars on hygroscopic mineral surfaces.
ra0002">The ideal periods are mostly during nighttime between 2–7 am.
ra0003">At most of the former landing sites such microscopic liquid could have appeared.
ra0004">We predict these ideal periods for the ExoMars rover’s candidate landing sites.
ra0005">This period at the primary landing site (Oxia Planum) is LS = 115–225 and in Local Time = 2–5.