Water is a vital molecule for all living species on Earth. While some organisms have been discovered that can survive in conditions of high amounts of ionizing radiation, very high or low temperatures, and high pressure, no life form has yet been found for which water is not essential. For example, plants produce food by converting hydrogen in water into sugar. However, finding water isn’t enough when investigating whether there is life outside of Earth; the water must also be in a liquid state. This is why NASA’s Kepler spacecraft is searching for Earth-like planets on the surface where liquid water can exist.
From the atoms that make up water, oxygen attracts the electrons used in bond formation more strongly than hydrogen atoms. As a result, water is polar, and many substances can dissolve in it. This characteristic makes water an important part of the circulatory system in living organisms, providing a suitable environment for the transport of nutrients, elements, and gases necessary for the body’s tissues. Additionally, many biochemical compounds, such as sugars, amino acids, and proteins, are soluble in water. Without these biochemical processes, an organism cannot survive. Water, being a good solvent, is an indispensable part of these processes (e.g., photosynthesis, digestion, respiration).
The efficiency of enzymes, which facilitate biochemical reactions, is easily affected by temperature changes. Due to its relatively high heat capacity (the amount of energy required to raise its temperature by 1°C), water has a stabilizing effect on temperature.
Furthermore, water can absorb thermal radiation in infrared wavelengths, contributing to providing suitable conditions for life on Earth
Data obtained from Jupiter’s moon Europa in recent years gives hope to scientists in their search for life outside of Earth. Evidence suggests that liquid water may exist under the ice sheet covering Europa’s surface due to geological activities and the heat released as a result of friction caused by tides.