Unmanned Planetary Exploration

Unmanned Planetary Exploration

Intelligent life on Earth first reveals itself through the geometric regularity of its constructions. If Percival Lowell’s canal network really existed, the conclusion that intelligent beings inhabit Mars might be similarly compelling. For life to be detected on Mars photographically, even from Mars orbit it must likewise have accomplished a major reworking of the surface. Technical civilization, canal builders, might be easy to detect. But except for one or two enigmatic features, nothing of the sort is apparent in the exquisite profusion of Martian surface detail uncovered by unmanned spacecraft.

However, there are many other possibilities, ranging from large plants and animals to microorganisms, to extinct forms, to a planet that is now and was always lifeless. Because Mars is farther from the Sun than is the Earth, its temperatures are considerably lower. Its air is thin, containing mostly carbon dioxide but also some molecular nitrogen and argon and very small quantities of water vapor, oxygen and ozone. Open bodies of liquid water are impossible today on Mars because of the atmospheric pressure on the planet is too low to keep even cold water from rapidly boiling. There may be minute quantities of liquid water in pores and capillaries in the soil. The amount of oxygen is far too little for a human being to breath. The ozone abundance is so small that germicidal ultraviolet radiation from the Sun strikes the Martian surface unimpeded. Could any organism survive in such an environment?

The Universe is fragile. It must be cherished. Image: © Megan Jorgensen

The Soviet Union maintained an active program of unmanned planetary exploration. Every year or two the relative positions of the planets and the physics of Kepler and Newton permitted the launch of a spacecraft to Mars and Venus with a minimum expenditure of energy. Since the early 1960’s the Soviet Union missed few such opportunities. Soviet persistence and engineering skills have eventually paid off handsomely.

Five Soviet spacecraft – Veneras 8 through 12 – have landed on Venus and successfully returned data from the surface, no insignificant feat in so hot, dense and corrosive a planetary atmosphere. Yet despite many attempts, the Soviet Union has never landed successfully on Mars – a place that, at least at first sight, seems more hospitable, with chilly temperatures, a much thinner atmosphere and more benign gases; with polar ice caps, clear pink skies, great sand dunes, ancient river beds, a vast rift valley, the largest volcanic construct, so far as we know, in the solar system, and balmy equatorial summer afternoons. It is a far more Earth-like world than Venus.