Titan Read Online Free Page A

such as hydrogen cyanide, cyanogen, and cyanoacetelyne. Shine sunlight on such an atmosphere and you get the same result you would in Los Angeles or Tokyo or Mexico City: photochemical smog, induced by solar ultraviolet light. Titan is a smog-covered world. Its predominantly orange coloring is due to this smog, which blankets Titan and makes it necessary for observations of its surface to be done in infrared wavelengths, which penetrate the smog, rather than visible light, which does not.
    The incoming solar ultraviolet light, together with energetic electrons from nearby Saturn’s powerful magnetosphere, produce complex chemical reactions high in Titan’s thick atmosphere. Organic polymers called tholins are created, to drift downward deeper into the atmosphere and eventually fall onto the moon’s surface: black snow.
    Laboratory experiments on Earth showed that tholins, when
dissolved in liquid water, yield amino acids, which are the building-block molecules of proteins and thus fundamental to life.
    Orbiting more than a million kilometers from Saturn, which in turn lies twice as far from the Sun as Jupiter and ten times farther from the Sun than the Earth does, Titan’s surface temperature averages -183° Celsius. Titan is cold, too cold to have liquid water on its surface—except when a region might be heated temporarily by a volcanic eruption or the impact of a meteor. Or if the water is mixed with an antifreeze compound, such as ammonia or ethane derivatives.
    Titan’s density is not quite twice that of water, which means that its body must be composed largely of ices—frozen water and/or frozen methane—with perhaps a small rocky core beneath a thick icy mantle.
    Despite Titan’s low temperature, liquid droplets of ethane can form in its atmosphere and rain down onto the frigid surface, collecting as lakes or perhaps larger seas. There are streams of ethane (or ethane-laced water) carving out channels across the ground of ices. Several sizable seas of hydrocarbon-crusted liquid methane dot the moon’s surface.
    Titan rotates on its axis in slightly less than sixteen Earth days, the same period as its orbit around Saturn. Thus Titan is “locked” in its rotation so that it always presents the same face to its planet, Saturn, just as our Moon presents the same face to Earth. But even a “locked” moon wobbles slightly in its orbit, and Titan’s rotation is perturbed slightly by its sizable neighbors, the moons Rhea and Hyperion, each of which is close to 1,500 kilometers in diameter. Titan rocks slightly back and forth as it orbits Saturn, a ponderous wobbling that creates strange tides in its hydrocarbon seas.
    A world rich in carbon, hydrogen and nitrogen. A world where raindrops of ethane and sooty flakes of tholins fall from the smoggy sky. A world that contains rivers and streams of ethane or ethane-laced water, and methane seas. Although it is a very cold world, a primitive form of microbial cryogenic biology was found to exist on Titan’s surface by the earliest automated probes from distant Earth. Could there be a more sophisticated biosphere, perhaps deeper underground?

    And there are large swaths of dark material carpeting parts of Titan’s surface. Early probes showed that they are rich in carbon compounds. Fields of frozen petroleum? Patches of solidified hydrocarbons? Swales of black tholin snowbanks piled on ground that is too cold for them to melt?
    Or something else?

24 DECEMBER 2095: CHRISTMAS EVE PARTY

    E duoard Urbain smiled uneasily as he shook hands, one by one, with each member of his scientific and engineering staffs. They shuffled themselves into a reception line the moment he entered the auditorium, like serfs of old lining up with their hats in their hands to receive the Christmas blessing of their lord and master.
    Jeanmarie, standing beside him, smiled graciously and spoke a few words to every man and woman presented to her. She is wonderful, Urbain thought, as he shook hand