sentences:  Because Lake Vostok may contain an environment sealed off below the ice for millions of years, the conditions could resemble those of ice-covered oceans hypothesized to exist on Jupiter's moon Europa, and Saturn's moon Enceladus.Russian scientist Peter Kropotkin first proposed the idea of fresh water under Antarctic ice sheets at the end of the 19th century.He theorized that the tremendous pressure exerted by the cumulative mass of thousands of vertical meters of ice could decrease the melting point at the lowest portions of the ice sheet to the point where the ice would become liquid water.