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