Pale Blue Dot - Carl Sagan [62]
ALL WORLDS WITH NONBLACK SKIES have atmospheres. If you’re standing on the surface and there’s an atmosphere thick enough to see, there’s probably a way to fly through it. We’re now sending our instruments to fly in the variously colored skies of other worlds. Someday we will go ourselves.
Parachutes have already been used in the atmospheres of Venus and Mars, and are planned for Jupiter and Titan. In 1985 two French-Soviet balloons sailed through the yellow skies of Venus. The Vega 1 balloon, about 4 meters across, dangled an instrument package 13 meters below. The balloon inflated in the night hemisphere, floated about 54 kilometers above the surface, and transmitted data for almost two Earth days before its batteries failed. In that time it traveled 11,600 kilometers (nearly 7,000 miles) over the surface of Venus, far below. The Vega 2 balloon had an almost identical profile. The atmosphere of Venus has also been used for aerobraking—changing the Magellan spacecraft’s orbit by friction with the dense air; this is a key future technology for converting flyby spacecraft to Mars into orbiters and landers.
A Mars mission, scheduled to be launched in 1998, and led by Russia, includes an enormous French hot air balloon—looking something like a vast jellyfish, a Portuguese man-of-war. It’s designed to sink to the Martian surface every chilly twilight and rise high when heated by sunlight the next day. The winds are so fast that, if all goes well, it will be carried hundreds of kilometers each day, hopping and skipping over the north pole. In the early morning, when close to the ground, it will obtain very high resolution pictures and other data. The balloon has an instrumental guide-rope, essential for its stability, conceived and designed by a private membership organization based in Pasadena, California, The Planetary Society.
Since the surface pressure on Mars is approximately that at an altitude of 100,000 feet on Earth, we know we can fly airplanes there. The U-2, for example, or the SR-71 Blackbird routinely approaches such low pressures. Aircraft with even larger wingspans have been designed for Mars.
The dream of flight and the dream of space travel are twins, conceived by similar visionaries, dependent on allied technologies, and evolving more or less in tandem. As certain practical and economic limits to flight on Earth are reached, the possibility arises of flying through the multihued skies of other worlds.
IT IS NOW ALMOST POSSIBLE to assign color combinations, based on the colors of clouds and sky, to every planet in the Solar System—from the sulfur-stained skies of Venus and the rusty skies of Mars to the aquamarine of Uranus and the hypnotic and unearthly blue of Neptune. Sacre-jaune, sacre-rouge, sacre-vert. Perhaps they will one day adorn the flags of distant human outposts in the Solar System, in that time when the new frontiers are sweeping out from the Sun to the stars, and the explorers are surrounded by the endless black of space. Sacre-noir.
*Like “gosh-darned” and “geez,” this phrase was originally a euphemism for those who considered Sacre-Dieu!, “Sacred God!,” too strong an oath, the Second Commandment duly considered, to be uttered aloud.
CHAPTER 11
EVENING AND MORNING STAR
This is another world
Which is not of men.
—LI BAI, “QUESTION AND ANSWER IN THE MOUNTAINS”
(CHINA, TANG DYNASTY, CA. 730)
You can see it shining brilliantly in the twilight, chasing the Sun down below the western horizon. Upon first glimpsing it each night, people were accustomed to make a wish (“upon a star”). Sometimes the wish came true.
Or you can spy it in the east before dawn, fleeing the rising Sun. In these two incarnations, brighter than anything else in the sky except only the Sun and the Moon, it was known as the evening and the morning star. Our ancestors did not recognize it was a world, the same world, never too far from the Sun because it is in