Destination Mars by Rod Pyle Read Free Book Online Page B

perspective. And this was just the imaging system—there were eight other experiments on board, most of which needed to perform in a timely fashion near Mars (one, an ionization chamber experiment to measure charged particles, had malfunctioned on the way from Earth).
    Worthy of mention is the occultation experiment, simple in design but very effective. At the moment that Mariner 4 began to go “behind” Mars from Earth's perspective, a radio transmission was scheduled to allow JPL to measure the effect of the Martian atmosphere on the radio waves. This allowed for a basic measurement of atmospheric density, the first proper measure of this property. It was far, far lower than expected—about 4 millibars. Prior to this it was thought to be perhaps 30 millibars. This was just one more nail in the coffin of the old Mars of the popular imagination (Earth is about 1,000 millibars).
    Many hours after the flyby, when the imaging playback had been collected at JPL, the data was fed through huge, state-of-the-art computers that were so slow that the imaging team took to posting the numerical printouts on the walls and using felt-tipmarkers or pencils to approximate the black-and-white value of the digits; they literally painted pixels. This gave them roughly shaded approximations of the imagery to enjoy until the computers had crunched through their tasks.
    Between these and the later computer-built images, Mars was finally visible in all his martial glory. After centuries of blurry images through telescopes, always wavering and swimming in-and-out of focus at the whimsy of the Earth's turbulent atmosphere, the Mariner science team could finally see the surface of the Red Planet as it truly existed. It was a thrilling, game-changing moment.
    The many craters visible were something of an epiphany to many Earth-bound observers. While it was suspected that the surface would be older than our planet's, the evidence of myriad craters, some huge, caused scientists to speculate that the planet's surface was not only very old but also relatively unaffected by erosion from weather or significant volcanic activity. Mars was declared, in general terms, a dead world. Later investigations would recant this to some degree; it is far from dead, though not lush by any stretch of the imagination. It has simply been far more active in weather and water terms than was thought at the time.
    While it was stunning to see Mars looking much like Earth's own moon, not everybody was gratified. There were still many “Lowellians” out there insisting that the Mars they had held so dear in their mind's eye might still live. In short, they were not ready to let go. Ideas were hatched about underground civilizations, hidden structures, and subresolution indicators of advanced life (the Mariner 4 cameras were very low-res by modern standards). Only the later Mariner 9 and, finally, Viking probes would put these notions to rest for all but the most fanatical or asylum-bound.
    But in an ironic twist, these folk were not all wrong. The low-resolution Mariner images showed a macroview of the Martian environment but were unable to resolve the more delicate andsubtle features of this very complex planet. While large craters were visible, the gentle erosion of their rims by wind and sand was not evident. While broad plains showed up, the intense water-sculpted features were invisible. And so, while the canals were most certainly obliterated and the dying cities vanished without a trace, the chance for a once-warmer, wetter Mars, perhaps even hosting microbial life-forms, existed within the shadows of those twenty-one pictures.
    One interesting characteristic of this flight was the attempted use of solar-wind steering augmentation. Each of the four solar panels, spread like an iron cross out to each side, had an additional “petal” extending from its tip, consisting of a skeletal frame covered with Mylar® foil. These outboard vanes were steerable and could be