Carl sagan — contact. chapter 16 — the elders of ozone

CHAPTER 16
The Elders of Ozone

AT A FEW hundred kilometers altitude, the Earth fills half your sky, and the band of blue that stretches from Mindanao to Bombay, which your eye encompasses in a single glance, can break your heart with its beauty.

Home, you think. Home. This is my world. This is where I come from. Everyone I know, everyone I ever heard of, grew up down there, under that relentless and exquisite blue. You race eastward from horizon to horizon, from dawn to dawn, circling the planet in an hour and a half. After a while, you get to know it, you study its idiosyncrasies and anomalies. You can see so much with the naked eye. Florida will soon be in view again. Has that tropical storm system you saw last orbit, swirling and racing over the Caribbean, reached Fort Lauderdale? Are any of the mountains in the Hindu Kush snow-free this summer? You tend to admire the aquamarine reefs in the Coral Sea. You look at the West Antarctic Ice Pack and wonder whether its collapse could really inundate all the coastal cities on the planet.

In the daylight, though, it's hard to see any sign of human habitation. But at night, except for the polar aurora, everything you see is due to humans, humming and blinking all over the planet. That swath of light is eastern North America, continuous from Boston to Washington, a megalopolis in fact if not in name. Over there is the burnoff of natural gas in Libya. The dazzling lights of the Japanese shrimp fishing fleet have moved toward the South China Sea. On every orbit, the Earth tells you new stories. You can see a volcanic eruption in Kamchatka, a Saharan sandstorm approaching Brazil, unseasonably frigid weather in New Zealand. You get to thinking of the Earth as an organism, a living thing. You get to worry about it, care for it, wish it well. National boundaries are as invisible as meridians of longitude, or the Tropics of Cancer and Capricorn. The boundaries are arbitrary. The planet is real. Spaceflight, therefore, is subversive. If they are fortunate enough to find themselves m Earth orbit, most people, after a little meditation, have similar thoughts. The nations that had instituted spaceflight had done so largely for nationalistic reasons; it was a small irony that almost everyone who entered space received a startling glimpse of a transnational perspective, of the Earth as one world.

It wasn't hard to imagine a time when the predominant loyalty would be to this blue world, or even to the cluster of worlds huddling around the nearby yellow dwarf star on which humans, once unaware that every star is a sun, had bestowed the definite article: the Sun. It was only now, when many people were entering space for long periods and had been afforded a little time for reflection, that the power of the planetary perspective began to be felt. A significant number of these occupants of low Earth orbit, it turned out, were influential down there on Earth.

They had — from the beginning, from before humans ever entered space — sent animals up there. Amoebas, fruit flies, rats, dogs, and apes had become hardy space veterans. As spaceflights of longer and longer duration became possible, something unexpected was found. It had no effect on microorganisms and little effect on fruit flies. But for mammals, it seemed, zero gravity extended the lifespan. By 10 or 20 percent. If you lived in zero g, your body would spend less energy fighting the force of gravity, your cells would oxidize more slowly, and you would live longer.