It appears certain now that water exists on the surface of Mars both as ice and as liquid. A recent report by S . H. Zisk and P. J. Mouginis-Mark indicates that liquid water exists in Mars' southern hemisphere at the area of Solis Lacus (Lake of the Sun). Interestingly enough, the results were obtained from radar data from earth-based stations rather than from Viking spacecraft. The reason for this is that data from the Viking orbiters showed a rough, evidently solid, frozen surface. Images from the Viking spacecraft were obtained during the Martian winter, but the earth-based radar measurements were obtained in the Martian summer.