A Step Farther Out (28 page)

Now we can write the article, right? Wrong. The problem is that last column in Figure 22. Just how do we expect to get delta v as big as all that?

Let's illustrate. As we've shown already, delta v can be calculated from mass ratio and exhaust velocity. (If you came in late, take my word for it; we'll get past the numbers pretty quickly.)

Now you could hardly call a drive
economical
if the mass ratio were much worse than, say, three, which means that if you start with 1,000 tons you'll arrive with 333. What, then, must our exhaust velocity be to make the simple trip from Earth to Mars?

It's horrible. About 2,204 kilometers/second, and what's horrible about that is it corresponds to a temperature of 50 million degrees Kelvin. The interiors of stars are that hot, but nothing else is.

Just how are we going to
contain
a temperature like that?

One answer might be that we'd better learn how; fusion power systems may require it. OK, and the fusion boys are working on the problem. However they solve it, we can be sure it won't be anything small that does the trick.

It's going to take enormous magnetic fields, superconductors, heavy structures, and a great deal more. After all, nothing material can hold a temperature like that without instantly vaporizing, and even containing the magnetic field that holds that kind of energy is no simple job.

Let's assume we can contain fusion reactions, though. We know immediately that energy is going to be no problem for our interplanetary civilization. With plentiful energy we'll find that a number of our other problems vanish.

There won't be many "rare" materials, for example; if they're rare and valuable enough, we'll simply
make
them out of atomic building blocks. Of course it may be cheaper to go find them somewhere, such as on Mars or among the asteroids, but we'll always be up against competition from the transmuters.

Life on Earth, at least among the people of the high-energy civilizations, will change drastically. Pollution will cease to be a problem (unless the fusion plants themselves are polluters, which isn't impossible). The Affluent Society will be with us, and possibly so will be regulations and rules, bureaucracy, and all the other niceties of a universal middle class.

All this comes as a result of assuming our space drive. More central to our immediate topic is the fact that the ships will be quite large—
Queen Mary
or supertanker size, not one-man prospector jobs. Someone is going to have to put up a lot of capital to build them, and it's not likely to be the Bobbsey Twins and their kindly uncle building ships in the backyard.

Only governments or very large international corporations will be in the space ship operating business, that's for sure. Thus there have to be profits in interplanetary travel. Not even governments will build more than one of these ships simply for scientific reasons. There's got to be commercial traffic.

Next, there's a technological problem: assuming we have fusion power and a method of getting electricity from it doesn't necessarily give us a space drive. Contrary to the notions of a lot of high school science teachers back in the 40's, rockets don't "need air to push against"; but the rocket exhaust certainly does need something on the rocket to push against.

What can that be? Perhaps some kind of magnetic field, but an open-end fusion system is at least two orders of magnitude harder to build than a "simple" system for generating electricity. It's one thing to take 50 million degrees and suck electricity out of it, and quite another to use that as a reaction drive.

Perhaps I'm not sufficiently imaginative, but for all these reasons I decided to shelve the one g system and design the article and story around something much simpler. In fact, if we had the electric power system, we could build these ships right now.

Ion drive systems solve the "something to push against" problem by shooting charged particles out the back end. The ship is charged, the particles are charged, and they repel each other. You can get very high exhaust velocities, in the order of 200 km/sec, with ion systems. They're among the most efficient drives known.

The trouble with present ion drives is that electricity costs weight. As an example, a currently useful system needs about 2100 kilowatts of power to produce one pound of thrust. Since the power plant weighs in the order of four tons, the total thrust is not one g, but about 1/10,000 of a gravity.

It works, but it's a little slow getting there. Not as slow as you might think: it would take about 140 days to go a full AU, and your ship would reach the respectable speed of 12 km/sec. Still, it's hardly interplanetary rapid transit.

Suppose, though, we had a fusion system to generate the electricity. It would undoubtedly weigh a lot: let's say 1000 metric tons, or about two million pounds, by the time we've put together the fusion system and its support units. We'd still come out ahead, because we'd have lots of power to play with. Assuming exhaust velocities of 200 km/sec, which we can get from present-day ion systems, we'd still have quite a ship.

She wouldn't be cheap, but it's not unreasonable to think of her as on a par with modern supertankers. She wouldn't be enormously fast: I've worked out the thrust for a ship massing about 100,000 tons with that drive, and she'd get only a hundredth of a g acceleration. Still, a trip from Earth to Ceres would take no more than 70 days, and that includes coasting a good part of the way to save mass.

A world-wide civilization was built around sailing ships and steamers making voyages of weeks to months. There's no reason to believe it couldn't happen in space.

IBS
Agamemnon
(Interplanetary Boost Ship) masses 100,000 tons as she leaves Earth orbit. She carries up to 2000 passengers with their life support requirements. Not many of these will be going first-class, though; many will be colonists, or even convicts, headed out steerage under primitive conditions.

Her destination is Pallas, which at the moment is 4 AU from Earth, and she carries 20,000 tons of cargo, mostly finished goods, tools, and other high-value items they don't make out in the Belt yet. Her cargo and passengers were sent up to Earth orbit by laser-launchers;
Agamemnon
will never set down on anything larger than an asteroid.

She boosts out at 10 cm/sec
²
, 1/100 gravity, for about 15 days, at which time she's reached about 140 km/second. Now she'll coast for 40 days, then decelerate for another 15. When she arrives at Pallas she'll mass 28,000 tons. The rest has been burned off as fuel and reaction mass. It's a respectable payload, even so.

The reaction mass must be metallic, and it ought to have a reasonably low boiling point. Cadmium, for example, would do nicely. Present-day ion systems want cesium, but that's a rare metal—liquid, like mercury—and unlikely to be found among the asteroids, or cheap enough to use as fuel from Earth.

In a pinch I suppose she could use iron for reaction mass. There's certainly plenty of that in the Belt. But iron boils at high temperatures, and running iron vapor through them would probably make an unholy mess out of the ionizing screens. The screens would have to be made of something that won't melt at iron vapor temperatures. Better, then, to use cadmium if you can get it.

The fuel would be hydrogen, or, more likely, deuterium, which they'll call "dee." Dee is "heavy hydrogen," in that it has an extra neutron, and seems to work better for fusion. We can assume that it's available in tens-of-ton quantities in the asteroids. After all, there should be water ice out there, and we've got plenty of power to melt it and take out hydrogen, then separate out the dee.

If it turns out there's no dee in the asteroids it's not a disaster. Shipping dee will become one of the businesses for interplanetary supertankers.

Thus we have the basis for an economy. Whatever people go to the Belt for, they'll need goods from Earth to keep them alive at first. Later they'll make a lot of their own, and undoubtedly there will be specialization. One rock will produce water, another steel, and yet another will attract technicians and set up industry. One may even specialize in food production.

Travel times are long but not impossible. They change, depending on when you're going where. It costs money to boost cargo all the way, so bulk stuff like metals and ice may be put in the "pipeline": given enough delta v to put the cargo into a transfer orbit. Anywhere from a year to several years later the cargo will arrive at its destination. If there are steady supplies, the deliveries are quite regular after the first long wait.

Speculators may buy up "futures" in various goods, thus helping capitalize the delivery system.

People wouldn't travel from rock to rock much. Thus each inhabited asteroid will tend to develop its own peculiar culture and
mores.
On the other hand, they will communicate easily enough. They can receive educational television from more advanced colonies. They can exchange both technical and artistic programs, and generally appreciate each other's problems and achievements.

What kind of people will go out there? Remember that life on Earth is likely to be soft: those going out will be unhappy about something. Bureaucracy, perhaps. Fleeing their spouses. Sent by a judge who wants them off the Earth. Adventurers looking to make a fortune. Idealists who want to establish a "truly free society." Fanatics for some cult or another who want to raise their children "properly."

All this begins to sound familiar: something like the colonial period with elements as late as just before WW I.

On the other hand, the "frontier" conditions will be so different from Earth that the Belters may not be too concerned with Earth. What Earth does about them is another story.

Given fusion power, Earth could go either of two ways: fat and happy, ignoring the nuts who want to live on other planets and asteroids; or officious, trying to govern the colonies, and sending up Air Force or Navy ships to enforce edicts set down by bureaucrats who've been outside once for a month and didn't like it.

Obviously there's a story or two in either alternative.

What kind of government will evolve if the rocks are left to themselves?

Well, each might
seek
independence, but they wouldn't
be
independent. They'd depend entirely too much on commerce. Given the enormous investments required to build the ships that carry that commerce, they'd depend on big moneyed interests, whether private or government.

The outfits that control the shipping will make most of the rules, then. They might not reach down into the colonies themselves to spell out laws and regulations, but the big decisions will be theirs. If we envision several large competing companies getting into the act, we can envision more Belt freedom through exploiting that competition.

The corporations themselves will have to set up some kind of corporate "United Nations," simply because you can't do business without enforcement of contracts, reasonably stable currencies, and the like. Their system may or may not be influenced by pressure from Earth—depending on how much Earth even cares.

There are probably other futures that can be built up
from
ships of this kind, but that is one reasonably consistent picture of life among the asteroids.

I think I might like it.

Editor's note: the story "Tinker," which was based on this chapter, was nominated for a Hugo for Best Novelette of the Year.

I'm writing most of this in a hotel room in Toronto, which is a lovely city but no place to be if you're alone on a Sunday night, and especially no place to be if you're from California: jet lag keeps you from getting to sleep at a normal hour, and the Provincial Police keep you from finding an open tavern. . .

It has been an interesting day. I've just taken part in a Canadian TV program called "The Great Debate." The issue was, "Resolved: space research is a waste of time and money." Anyone who doesn't know- which side I took shouldn't be reading this book Anyone who believes I lost the debate hasn't been reading it very carefully.

I slaughtered the poor chap. It helps that my opponent, John Holt, who is a charming fellow with a distinguished record in education, chose such a silly proposition to defend. It is trivially easy to show that space research has pretty well paid for itself already. I chose, in fact, to assert a new proposition: that the space program is the most important activity, excluding religion, in human history.

They tape 'The Great Debate" in bunches, and prior to my own I watched another: Max Lerner and Toynbee's successor at Cambridge debating the proposition that Western Civilization is in a state of irreversible and imminent collapse. As I listened it came to me that their whole conversation was irrelevant. It was as if a pair of very distinguished and learned professors in Paris were debating the same subject in 1491, unaware that this Genoese nut was making application to the Queen of Spain for a small fleet. . .

And of course I said as much in my own debate, and added that very probably in Iceland a few centuries earlier someone had won in a debate of, "Resolved, the voyages of Leif Ericson are a waste of time and money." To which Mr. Holt replied that the New World was accessible to the average family, while space never would be; that space would be restricted to scientists, astronauts, and military officers, a chosen few. The general public would never be able to go. He didn't say why.

Now at first the New World was pretty well inaccessible to anyone who couldn't get Queen Isabella to hock the crown jewels, and space is in the same situation at present; but just as the Americas were soon open to workers, farmers, administrators, soldiers, adventurers, some qualified, some merely desperate, some sent as sentence of courts, space will, probably well within my own lifetime, be open to large numbers—at least if Mr. Holt doesn't get his way. The only real question is how and when.

The how is simple technology. Shuttles will help a lot. Eventually, I trust, there will come the laser launching systems I described earlier, which can put up privately owned capsules, the equivalent of the covered wagon. There will be O'Neill Colonies—which Mr. Holt particularly hates; Luna bases; asteroid mining and refineries; Mars colonies; possibly Enceladus and the Mars-forming Project; all these and more are in the cards and there's no reason to suppose they'll be restricted to super-heroes.