Ah, but not explored by men—and the distances are so great. Surely they are . . . by free-fall orbits, which is all that we have been using. But there are numerous proposals (and not all ours!) for constant-boost ships, proposals that require R&D on present art only—no breakthroughs.
Reach for your pocket calculator and figure how long it would take to make a trip to Mars and back if your ship could boost at one-tenth gee. We will omit some trivia by making it from parking orbit to parking orbit, use straight-line trajectories, and ignore the Sun's field—we'll be going uphill to Mars, downhill to Earth; what we lose on the roundabouts we win on the shys.
These casual assumptions would cause Dan Alderson, ballistician at Jet Propulsion Laboratory, to faint. But after he comes out of his faint he would agree that our answers would be of correct close order of magnitude—and all I'm trying to prove is that even a slight constant boost makes an enormous difference in touring the Solar System. (Late in the 21st century we'll offer the Economy Tour: Ten Planets in Ten Days.)
There are an unlimited number of distances between rather wide parameters for an Earth-Mars-Earth trip but we will select one that is nearly minimum (it's cheating to wait in orbit at Mars for about a year in order to take the shortest trip each way . . . and unthinkable to wait years for the closest approach). We'll do this Space Patrol style: There's Mars, here we are at L-5; let's scoot over, swing around Mars, and come straight home. Just for drill.
Conditions: Earth-surface gravity (one "gee") is an acceleration of 32.2 feet per second squared, or 980.7 centimeters per second squared. Mars is in or near opposition (Mars is rising as Sun is setting). We will assume that the round trip is 120,000,000 miles. If we were willing to wait for closest approach we could trim that to less than 70,000,000 miles . . . but we might have to wait as long as 17 years. So we'll take a common or garden variety opposition—one every 26 months—for which the distance to Mars is about 50- to 60,000,000 miles and never over 64 million.
(With Mars in conjunction on the far side of the Sun, we could take the scenic route of over 500 million miles—how much over depends on how easily you sunburn. I suggest a minimum of 700 million miles.)
You now have all necessary data to figure the time it takes to travel Earth-Mars-Earth in a constant-boost ship—any constant-boost ship—when Mars is at opposition. (If you insist on the scenic route, you can't treat the trajectory approximations as straight lines and you can't treat space as flat but a bit uphill. You'll need Alderson or his equal and a big computer, not a pocket calculator; the equations are very hairy and sometimes shoot back.)
But us two space cadets are doing this by eyeballing it, using Tennessee windage, an aerospace almanac, a Mickey Mouse watch, and an SR-50 Pop discarded years ago.
We need just one equation: Velocity equals acceleration times elapsed time: v = at
This tells us that our average speed is ½at—and from that we know that the distance achieved is the average speed times the elapsed time: d = ½at2
If you don't believe me, check any physics text, encyclopedia, or nineteen other sorts of reference books—and I did that derivation without cracking a book but now I'm going to stop and find out whether I've goofed—I've had years of practice in goofing. (Later—seems okay.)
Just two things to remember: 1) This is a 4-piece trip—boost to midpoint, flip over and boost to brake; then do the same thing coming home. Treat all four legs as being equal or 30,000,000 miles, so figure one of them and multiply by four (Dan, stop frowning; this is an approximation . . . done with a Mickey Mouse watch.)
2) You must keep your units straight. If you start with centimeters, you are stuck with centimeters; if you start with feet, you are stuck with feet. So we have ¼ of the trip equals 5280 x 30,000,000 = 1.584 x 1011 feet, or 4.827 x 1012 centimeters.
One last bit: Since it is elapsed time we are after, we will rearrange that equation (d = ½at2) so that you can get the answer in one operation on your trusty-but-outdated pocket calculator . . . or even on a slide rule, as those four-significant-figures data are mere swank; I've used so many approximations and ignored so many minor variables that I'll be happy to get answers correct to two significant figures.
d is 30,000,000 miles expressed in feet, or 158,400,000,000. Set that into your pocket calculator. Divide it by one half of one tenth of gee, or 1.61. Push the square root button. Multiply by 4. You now have the elapsed time of the round trip expressed in seconds so divide by 3600 and you have it in hours, and divide that by 24 and you have it in days.
At this point you are supposed to be astonished and to start looking for the mistake. While you are looking, I'm going to slide out to the refrigerator.
There is no mistake. Work it again, this time in metric. Find a reference book and check the equation. You will find the answer elsewhere in this book but don't look for it yet; we'll try some other trips you may take by 2000 A.D. if you speak Japanese or German—or even English if Proxmire and his ilk fail of reelection.
Same trip, worked the same way, but at only one percent of gee. At that boost I would weigh less than my shoes weigh here in my study.
Hmmph! Looks as if one answer or the other must be wrong.
Bear with me. This time we'll work it at a full gee, the acceleration you experience lying in bed, asleep. (See Einstein's 1905 paper.)
(Preposterous. All three answers must be wrong.)
Please stick with me a little longer. Let's run all three problems for a round trip to Pluto—in 2006 A.D., give or take a year. Why 2006? Because today Pluto has ducked inside the orbit of Neptune and won't reach perihelion until 1989—and I want it to be a bit farther away; I've got a rabbit stashed in the hat.
Pluto ducks outside again in 2003 and by 2006 it will be (give or take a few million miles) 31.6 A.U. from the Sun, figuring an A.U. at 92,900,000 miles or 14,950,000,000,000 centimeters as we'll work this both ways, MKS and English units. (All right, all right—1.495 x 1013 centimeters; it gets dull here at this typewriter.)
Now work it all three ways, a round trip of 63.2 A.U. at a constant boost of one gravity, one tenth gravity, and one hundredth of a gee—and we'll dedicate this to Clyde Tombaugh, the only living man to discover a new planet—through months of tedious and painstaking examination of many thousands of films.
Some think that Pluto was once a satellite and its small size makes this possible. But it is not a satellite today. It is both far too big and hundreds of millions of miles out of position to be an asteroid. It can't be a comet. So it's a planet—or something so exotic as to be still more of a prize.
Its size made it hard to find and thus still more of an achievement. But Tombaugh continued the search for seventeen weary years and many millions more films. If there is an Earth-size planet out there, it is at least three times as distant as Pluto, and a gas giant would have to be six times as far. Negative data win no prizes but they are the bedrock of science.
Until James W. Christy on 22 June 1978 discovered Pluto's satellite, Charon, it was possible for us romantics to entertain the happy thought that Pluto was loaded with valuable heavy metals; the best estimate of its density made this plausible. But the mass of a planet with a satellite can be calculated quite easily and accurately, and from that, its density.
The new figure was much too low, only half again as heavy as water. Methane snow? Perhaps.
So once again a lovely theory is demolished by an awkward fact.
Nevertheless Pluto remains a most mysterious and most intriguing heavenly body. A planet the size and mass of Mars might not be too much use to us out there . . . but think of it as a fuel dump. Many stories and many nonfictional projections speak of using the gas giants and/or the rings of Saturn as sources of fuel. But if Pluto is methane ice or water ice or frozen hydrogen or all three, as a source of fuel—conventional, or fusion, or even reaction mass—Pluto has one supremely important advantage over the gas giants: Pluto is not at the bottom of a horridly deep gravity well.
Finish
ed calculating? Good. Please turn to page 299 and see why I wanted our trip to Pluto to be a distance of 31.6 A.U.—plus other goodies, perhaps.
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11. 1950 Your personal telephone will be small enough to carry in your handbag. Your house telephone will record messages, answer simple inquiries, and transmit vision.
1965 No new comment.
1980 This prediction is trivial and timid. Most of it has already come true and the telephone system will hand you the rest on a custom basis if you'll pay for it. In the year 2000, with modern telephones tied into home computers (as common then as flush toilets are today) you'll be able to have 3-dimensional holovision along with stereo speech. Arthur C. Clarke says that this will do away with most personal contact in business. I agree with all of Mr. Clarke's arguments and disagree with his conclusion; with us monkey folk there is no substitute for personal contact; we enjoy it and it fills a spiritual need.
Besides that, the business conference is often an excuse to loaf on the boss's time and the business convention often supplies some of the benefits of the Roman Saturnalia.
Nevertheless I look forward to holovideostereophones without giving up personal contacts.
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12. 1950 Intelligent life will be found on Mars.
1965 Predicting intelligent life on Mars looks pretty silly after those dismal photographs. But I shan't withdraw it until Mars has been thoroughly explored. As yet we really have no idea—and no data—as to just how ubiquitous and varied life may be in this galaxy; it is conceivable that life as we don't know it can evolve on any sort of a planet . . . and nothing in our present knowledge of chemistry rules this out. All the talk has been about life-as-we-know-it—which means terrestrial conditions.
But if you feel that this shows in me a childish reluctance to give up thoats and zitidars and beautiful Martian princesses until forced to, I won't argue with you—I'll just wait.
1980 The photographs made by the Martian landers of 1976 and their orbiting companions make the prediction of intelligent Martian life look even sillier. But the new pictures and the new data make Mars even more mysterious. I'm a diehard because I suspect that life is ubiquitous—call that a religious opinion if you wish. But remember two things: Almost all discussion has been about Life-as-we-know-it . . . but what about Life-as-we-don't-know-it? If there were Martians around the time that those amazing gullies and canyons were formed, perhaps they went underground as their atmosphere thinned. At present, despite wonderful pictures, our data are very sparse; those two fixed landers are analogous to two such landing here: one on Canadian tundra, the other in Antarctica—hardly sufficient to solve the question: Is there intelligent life on Sol III?
(Is there intelligent life in Washington, D.C.?)
Whistling in the dark—I think I goofed on this one. But if in fact Mars is uninhabited, shortly there will be a land rush that will make the Oklahoma land stampede look gentle. Since E = mc2 came into our lives, all real estate is potentially valuable; it can be terraformed to suit humans. There has been so much fiction and serious, able nonfiction published on how to terraform Mars that I shan't add to it, save to note one thing:
Power is no problem. Sunshine at that distance has dropped off to about 43% of the maximum here—but Mars gets all of it and gets it all day long save for infrequent dust storms . . . whereas the most that Philadelphia (and like places) ever gets is 35%—and overcast days are common. Mars won't need solar power from orbit; it will be easier to do it on the ground.
But don't be surprised if the Japanese charge you a very high fee for stamping their visa into your passport plus requiring deposit of a prepaid return ticket or, if you ask for immigrant's visa, charge you a much, much higher fee plus proof of a needed colonial skill.
For there is intelligent life in Tokyo.
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13. 1950 A thousand miles an hour at a cent a mile will be commonplace; short hauls will be made in evacuated subways at extreme speed.
1965 I must hedge number thirteen; the "cent" I meant was scaled by the 1950 dollar. But our currency has been going through a long steady inflation, and no nation in history has ever gone as far as we have along this route without reaching the explosive phase of inflation. Ten-dollar hamburgers? Brother, we are headed for the hundred-dollar hamburger—for the barter-only hamburger.
But this is only an inconvenience rather than a disaster as long as there is plenty of hamburger.
1980 I must scale that "cent" again. In 1950 gold was $35/troy ounce; this morning the London fix was $374/troy ounce. Just last week my wife and I flew San Francisco to Baltimore and return. We took neither the luxury class nor any of the special discounted fares; we simply flew what we could get.
Applying the inflation factor—35/374—our tickets cost a hair less than one cent a mile in 1950 dollars. From here on I had better give prices in troy ounces of gold, or in Swiss francs; not even the Man in the White House knows where this inflation is going. About those subways: possible, even probable, by 2000 A.D. But I see little chance that they will be financed until the dollar is stabilized—a most painful process our government hates to tackle.
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14. 1950 A major objective of applied physics will be to control gravity.
1965 This prediction stands. But today physics is in a tremendous state of flux with new data piling up faster than it can be digested; it is anybody's guess as to where we are headed, but the wilder you guess, the more likely you are to hit it lucky. With "elementary particles" of nuclear physics now totaling about half the number we used to use to list the "immutable" chemical elements, a spectator needs a program just to keep track of the players. At the other end of the scale, "quasars"—quasi-stellar bodies—have come along; radio astronomy is now bigger than telescopic astronomy used to be; and we have redrawn our picture of the universe several times, each time enlarging it and making it more complex—I haven't seen this week's theory yet, which is well, as it would be out of date before this gets into print. Plasma physics was barely started in 1950; the same for solid-state physics. This is the Golden Age of physics—and it's an anarchy.
1980 I stick by the basic prediction. There is so much work going on both by mathematical physicists and experimental physicists as to the nature of gravity that it seems inevitable that twenty years from now applied physicists will be trying to control it. But note that I said "trying"—succeeding may take a long time. If and when they do succeed, a spinoff is likely to be a spaceship that is in no way a rocket ship—and the Galaxy is ours! (Unless we meet that smarter, meaner, tougher race that kills us or enslaves us or eats us—or all three.)
Particle physics: the situation is even more confusing than in 1965. Physicists now speak of more than 200 kinds of hadrons, "elementary" heavy particles. To reduce this confusion a mathematical construct called the "quark" was invented. Like Jell-O quarks come in many colors and flavors . . . plus spin, charm, truth, and beauty (or top and bottom in place of truth and beauty—or perhaps "truth" doesn't belong in the list, and no jokes, please, as the physicists aren't joking and neither am I). Put quarks together in their many attributes and you can account for (maybe) all those 200-odd hadrons (and have a system paralleling the leptons or light particles as a bonus).
All very nice . . . except that no one has ever been able to pin down even one quark. Quarks, if they exist, come packaged in clumps as hadrons—not at random but by rules to account for each of that mob of hadrons.
Now comes Kenneth A. Johnson, Ph.D. (Harvard '55), Professor of Physics at the Massachusetts Institute of Technology (which certainly places him in the worldwide top group of physicists) with an article (Scientific American, July 1979, p. 112, "The Bag Model of Quark Confinement"), an article which appears to state that quarks will never be pinned down because they are in sort of an eternal purdah, never to be seen even as bubble tracks.
Somehow it reminds me of the dilemma when the snark is a boojum.
I'm not poking fun at D
r. Johnson; he is very learned and trying hard to explain his difficult subject to the unlearned such as I.
But, in the meantime I suggest reading The Hunting of the Snark while waiting patiently for 2000 A.D. We have a plethora of data; perhaps in twenty more years the picture will be simplified. Perhaps—
* * *
15. 1950 We will not achieve a "World State" in the predictable future. Nevertheless, Communism will vanish from this planet.
1965 I stand flatly behind prediction number fifteen.
1980 I still stand flatly behind the first sentence of that two-part prediction above. The second part I could weasel out of by pointing out that on this planet no state that calls itself Marxist or Socialist or Communist has ever established a system approximating that called for by the works of Karl Marx and Friedrich Engels. And never will; Marx's Utopia does not fit human beings. The state will not "wither away."
But I shan't weasel as I am utterly dismayed by the political events of the past 15–20 years. At least two thirds of the globe now calls itself Marxist. Another large number of countries are military dictatorships. Another large group (including the United States) are constitutional democratic republics but so heavily tinged with socialism ("welfare state") that all of them are tottering on the brink of bankruptcy and collapse.
So far as I can see today the only thing that could cause the soi-disant Marxist countries to collapse in as little time as twenty years would be for the United States to be conquered and occupied by the USSR—and twenty years ago I thought that this was a strong possibility. (I'm more optimistic now, under the present three-cornered standoff.)
If we were to be conquered and occupied, the Communist world might collapse rather quickly. We have been propping them up whenever they were in real trouble (frequently!) for about half a century.
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Expanded Universe Page 32
