Pale Blue Dot - Carl Sagan [45]
Should we expect an icy surface covered with deep tholin sediments, a hydrocarbon ocean with at most a few organic-encrusted islands poking up here and there, a world of crater lakes, or something more subtle that we haven’t yet figured out? This isn’t just an academic question, because there’s a real spacecraft being designed to go to Titan. In a joint NASA/ESA program, a spacecraft called Cassini will be launched in October 1997—if all goes well. With two flybys of Venus, one of Earth, and one of Jupiter for gravitational assists, the ship will, after a seven-year voyage, be injected into orbit around Saturn. Each time the spacecraft comes close to Titan, the moon will be examined by an array of instruments, including radar. Because Cassini will be so much closer to Titan, it will be able to resolve many details on Titan’s surface indetectable to Muhleman’s pioneering Earth-based system. It’s also likely that the surface can be viewed in the near infrared. Maps of the hidden surface of Titan may be in our hands sometime in the summer of 2004.
Cassini is also carrying an entry probe, fittingly called Huygens, which will detach itself from the main spacecraft and plummet into Titan’s atmosphere. A great parachute will be deployed. The instrument package will slowly settle through the organic haze down into the lower atmosphere, through the methane clouds. It will examine organic chemistry as it descends, and—if it survives the landing—on the surface of this world as well.
Nothing is guaranteed. But the mission is technically feasible, hardware is being built, an impressive coterie of specialists, including many young European scientists, are hard at work on it, and all the nations responsible seem committed to the project. Perhaps it will actually come about. Perhaps winging across the billion miles of intervening interplanetary space will be, in the not too distant future, news about how far along the path to life Titan has come.
*There could have been none. We’re very lucky that there is such a world to study. The others all have too much hydrogen, or not enough, or no atmosphere at all.
*Not because he thought it remarkably large, but because in Greek mythology members of the generation preceding the Olympian gods—Saturn, his siblings, and his cousins—were called Titans.
*Titan’s atmosphere has no detectable oxygen, so methane is not wildly out of chemical equilibrium—as it is on Earth—and its presence is in no way a sign of life.
CHAPTER 8
THE FIRST NEW PLANET
I implore you, you do not hope to be able to give the reasons for the number of planets, do you?
This worry has been resolved …
—JOHANNES KEPLER,
EPITOME OF COPERNICAN ASTRONOMY,
BOOK 4 (1621)
Before we invented civilization, our ancestors lived mainly in the open, out under the sky. Before we devised artificial lights and atmospheric pollution and modern forms of nocturnal entertainment, we watched the stars. There were practical calendrical reasons, of course, but there was more to it than that. Even today, the most jaded city dweller can be unexpectedly moved upon encountering a clear night sky studded with thousands of twinkling stars. When it happens to me, after all these years, it still takes my breath away.
In every culture, the sky and the religious impulse are intertwined. I lie back in an open field and the sky surrounds me. I’m overpowered by its scale. It’s so vast and so far away that my own insignificance becomes palpable. But I don’t feel rejected by the sky. I’m a part of it—tiny, to be sure, but everything is tiny compared to that overwhelming immensity. And when I concentrate on the stars, the planets, and their motions, I have an irresistible sense of machinery, clockwork, elegant precision working on a scale that, however lofty our aspirations, dwarfs and humbles us.
Most of the great inventions in human history—from stone tools and the