In this final program of a three-part series, Robert Neathery, Director of the Science Museum of Philadelphia's Franklin Institute, discusses the possibility of life on Mars by first defining the needs of life as we know it: water, oxygen, food, moderate temperatures, adaptation to gravitational forces, and protection from radiation. He then gives the history of Mars from Francesco Fontana's 1636 drawing of the planet to Christian Huygens' comments on possible inhabitants of Mars and Giovanni Schiaparelli's 1877 observation of Mars's channels (mistakenly translated as "canals" by others). Mr. Neathery describes a diagram of the planet's orbit between 1956-71 indicating its nearness to the earth every 15 years. Aerology, or the study of the features of Mars, is done with telescope, spectroscope, thermocouple, and camera and reveals polar caps that wax and wane and a reddish color, thought to be desert, covering 75% of the planet's surface. Dr. Neathery shows a cactus in a bell jar containing nitrogen, argon, carbon dioxide, and oxygen in proportions considered similar to those in the Martian atmosphere and compares it to a cactus plant outside the jar. He also uses balloons filled with nitrogen or helium to demonstrate the escape velocity of gravity on earth as compared to the lower surface gravity on Mars. Because oxygen is nearly non-existent on Mars, the temperatures are extreme, and it's unclear whether chlorophyll exists on the planet, Dr. Neathery concludes that Mars is inhospitable to life as we know it. However, he is certain that man's curiosity will take him there. The trip will take eight months, and an artist's rendition shows what will be seen upon landing. Dr. Neathery laments that the public's belief in Orson Welles's 1938 "War of the Worlds" radio broadcast is a sad commentary on their understanding of science.