Studies by Davis and Libby ([ref.32]) on the atmosphere of Jupiter support the possibility of the production of organic matter in its atmosphere in a manner analogous to the processes which may have led to the synthesis of organic molecules in the Earth’s early history. It is difficult to assess the possibility that life has evolved on Jupiter during the 4- or 5-billion-year period in which the planet has retained a reducing atmosphere. The question of extraterrestrial life and of the origin of life is interwoven. Discovery of the first and analysis of its nature may very well elucidate the second. The oldest form of fossil known today is that of a microscopic plant similar in form to common algae found in ponds and lakes. Scientists know that similar organisms flourished in the ancient seas over 2 billion years ago. However, since algae are a relatively complex form of life, life in some simpler form could have originated much earlier. Organic material similar to that found in modern organisms can be detected in these ancient deposits as well as in much older Precambrian rocks. Although the planets now have differing atmospheres, in their early stages the atmospheres of all the planets may have been essentially the same. The most widely held theory of the origin of the solar system states that the planets were formed from vast clouds of material containing the elements in their cosmic distribution. It is believed that the synthesis of organic compounds preceding the origin of life on Earth occurred before its atmosphere was transformed from hydrogen and hydrides to oxygen and nitrogen. This theory is supported by laboratory experiments of Calvin ([ref.16]), Miller ([ref.33]), and Oró ([ref.34]). The Earth’s present atmosphere consists of nitrogen and oxygen in addition to relatively small amounts of other gases; most of the oxygen is of biological origin. Some of the atmospheric gases, in spite of their low amounts, are crucial for life. The ultraviolet-absorbing ozone in the upper atmosphere and carbon dioxide are examples of such gases. Significant in the search for extraterrestrial life are the data (e.g., planet’s temperature) transmitted by Mariner II, which was launched from Cape Canaveral on August 27, 1962, and flew past Venus on December 14, 1962. Mariner II’s measurements showed temperatures on the surface of Venus of the order of 800° F, too hot for life as known on Earth.