"Paul Preuss - Venus Prime 2 - Maelstrom" - читать интересную книгу автора (Preuss Paul)

The other scientific element in тАЬMaelstrom IIтАЭ has a much longer history; itтАЩs the branch of celestial
mechanics known as тАЬperturbation theory.тАЭ IтАЩve been able to get considerable mileage out of it since my
applied maths instructor, the cosmologist Dr. George C. McVittie, introduced me to the subject at Kings
College, London, in the late тАЩ40s. However, IтАЩd come across itтАУwithout realizingтАУin dear old Wonder Stories
almost two decades earlier. HereтАЩs a challenge to you: spot the flaw in the following scenario. . . .

The first expedition has landed on Phobos, the inner moon of Mars. Gravity there is only about a thousandth
of EarthтАЩs, so the astronauts have a great time seeing how high they can jump. One of them overdoes it, and
exceeds the tiny satelliteтАЩs escape velocity of about thirty kilometers an hour. He dwindles away into the sky,
toward the mottled red Marscape; his companions realize that theyтАЩll have to take off and catch him before he
crashes into the planet only six thousand kilometers below.

A dramatic situation, which opens Lawrence ManningтАЩs 1932 serial тАЬThe Wreck of the Asteroid.тАЭ Manning,
one of the most thoughtful science fiction writers of the тАЩ30s, was an early member of the American Rocket
Society, and was very careful with his science. But this time, IтАЩm afraid, he was talking nonsense: his high
jumper would have been perfectly safe.

Look at his situation from the point of view of Mars. If heтАЩs simply standing on Phobos, heтАЩs orbiting the
planet at almost eight thousand kilometers an hour (a Moon that close to its primary has to move pretty fast).
As spacesuits are massive affairs, and not designed for athletic events, I doubt if the careless astronaut could
achieve that critical thirty kilometers an hour. Even if he did, it would be less than a half-percent of the
velocity he already has, relative to Mars. Whichever way he jumped, therefore, it will make virtually no
difference to his existing situation; heтАЩll still be traveling in almost the same orbit as before. HeтАЩd recede a
few kilometers away from PhobosтАУand be right back where he started, just one revolution later! (Of course,
he could run out of oxygen in the meantimeтАУthe trip round Mars will take seven-and-a-half hours. So maybe
his friends should go after himтАУat their leisure.)

This is perhaps the simplest example of тАЬperturbation theory,тАЭ and I developed it a good deal further in
тАЬJupiter VтАЭ (reprinted in Reach for Tomorrow, 1956). This story, incidentally, was based on what seemed a
cute idea in the early тАЩ50s. A decade earlier, LIFE Magazine had published space-artist Chesley BonestellтАЩs
famous paintings of the outer planets. WouldnтАЩt it be nice, I thought, if sometime in the 21st century LIFE
sent one of its photographers out there to bring back the real thing, and compare it with ChesleyтАЩs hundred-
year-old visions?

Well, little did I imagine that, in 1976, the Voyager space-probe would do just thisтАУand that, happily, Chesley
would still be around to see the result. Many of his carefully researched paintings were right on targetтАУthough
he couldnтАЩt have anticipated such stunning surprises as the volcanoes of Io, or the multiplex rings of Saturn.

Much more recently, Perturbation Theory plays a key role in 2061: Odyssey Three; and I wonтАЩt promise not
to use it again one of these days. It gives all sorts of opportunities for springing surprises on the unsuspecting
readerтАУ


file:///C|/Documents%20and%20Settings/harry/Bureaub...Preuss%20-%20Venus%20Prime%202%20-%20Maelstrom.html (3 of 180)23-12-2006 18:56:41
 ARTHUR C. CLARKE'S VENUS PRIME: VOLUME 2


тАУOver to you, Paul Preuss!