When we see the Space Shuttle launched, view color images from Neptune or listen to tales of space travel, it's a reminder that one day in the not-too-distant future we could be taking vacations on the moon.
Does that prospect seem outlandish--or out-worldish?
If you're a prudent bettor, don't wager against it. Odds are you'll lose, just as a half-century ago you'd have lost if you had bet that transoceanic vacations would never become commonplace.
The fact is, it's well within the realm of possibility to create a lunar colony and a transportation system to support it.
In science fiction, rockets have been the favorite way to ride the imagination to the moon and beyond, although wooden vessels suspended from balloons and blown by cosmic winds have had their partisans.
By the late 1940s, engineers, scientists and aerospace executives were starting to make serious proposals for real rocket ships and real space cities to be served by them.
Today, rocket launchings monopolize space flight, and there are a lot of them; in 1988, the Soviet Union alone launched 89 space missions. Rockets that will be bigger or better or both are on the way.
Yet the chances are that when you take your holiday on the moon, you'll not be borne there on the flame and thunder of a rocket. A better way is being dreamed up in labs and workshops around the world--in Great Britain and the United States, in the Soviet Union and Japan. The better way is a moon plane that, within Earth's atmosphere, will behave much like the airplanes you ride today.
In appearance the moon plane will combine the familiar with the alien. Its shapes and surfaces will be somewhat unfamiliar, but you will be able to recognize it as a plane.
Over the objections of today's airmen, it will have no windows, not even a windshield. You can have a sturdier, simpler hull, easier to build, if you do without them, and for surveillance, electronic scanners and other sensors will better serve the purpose.
When you board you'll find no conventional seats. Instead, you'll see what look like the progeny of a marriage between a recliner, and, well, a mummy case, one for each passenger. Each module will be operable by its occupant as well as by the flight attendants.
In addition to being an unconventional seat (or, at your preference, a bed) your moon-flight module will serve as a substitute for the anchor of gravity, to keep you from going adrift. It will also be your purveyor of services.
Within your self-contained module you'll access food and drink, manage your ambient temperature, operate the built-in sanitary facilities, select a range of postures, control your view screen, select entertainment channels and, of course, communicate with the cabin crew and with your traveling companions.
You'll go to the moon by plane rather than be lofted by rocket because rockets have the oddity that they cannot "breathe" the oxygen in the atmosphere as a jet engine can.
So even with oxygen all around them in the atmosphere, they must carry a large amount with them to power their ascent. They must stand poised on tiptoe, focus their energies beneath them and blast themselves off like controlled bombs. Their lift-off is a managed explosion.
Few transportation professionals are content with the prospect of trying to offer fare-paying passengers regularly scheduled service aboard that sort of volcanic contrivance.
With an air-breathing power plant, the moon plane will make a conventional takeoff, gently transferring its load from wheels to wings and then ascending at a comfortable gradient through the atmosphere.
To maneuver in airless space, the plane will use small thrusters similar to those on some of today's spacecraft.
Once in space you'll not be confined to your module. You'll be encouraged to emerge from it to experience the fun of floating with the aid of guidelines and handholds and under the tutelage of the flight attendants. With a little practice, turning a somersault in mid-nothing will become almost as easy as opening and closing your eyes.
But that will be only your second-favorite in-flight entertainment. Your first will be watching Earth recede and moon approach on your vision screen.
Long-range scanners will let you glimpse such sights as low-orbit space stations or a space tug outbound to retrieve a crippled satellite for repair. Generally, though, your flight path will stay well clear of other activities and objects. At space speeds, even a collision with an object the size of an aspirin tablet could be catastrophic.
Regularly scheduled passenger flights will traverse space ways that are cleaned, protected and controlled. That means that the principal space-faring nations will have devised an agency to operate space ways and to guard them from space litter, of which, believe it or not, there already is a dismally large accumulation.
The moon plane will take about 20 hours to reach the orbiting transfer station, from which tourists will descend by ferry to the lunar surface.
You will not be dragging along suitcases full of clothes. Weight, energy and storage space will not be wasted that way (a concept many a traveler has wished could be applied to Earth transportation). You can keep what you wore to the moon and wear it back, but on the moon you will wear simple garments of space-age fabrics that stay there and are recycled there.
We do not yet know whether there is ice on the moon to convert to water. What is certain is that it will be more efficient to convert moon matter for use than to transport necessities such as water from Earth. Energy probably will be supplied from solar sources. You will inhabit ecosystems that will function through recycling and renewal rather than through consumption and replacement.
In truth, they will be small re-creations of our Earth environment, but to preserve them we shall have to treat them far more sensibly than we now do Earth's environment. In doing so, we will perhaps learn how to treat Earth's better, too.
The moon's gravity is about one-sixth that of Earth's. If you can drive a golf ball 200 yards on Earth, you'll be dismayed when you hit it quite out of sight on a lunar course--unless you're allowed to use brightly colored, basketball-size golf balls.
A golf course on the moon? Maybe, maybe not. But don't forget that in addition to its educational and recreational value, moon tourism, like tourism on Earth, will be important to economic development.
Moon tourism will be fostered because it will help to pay the expenses of other activities, such as the movement of cargo--supplies outbound and products inbound. The vast scale of investment that will be made in tourist plant and services on the moon is foreshadowed by those made, for example, in today's theme parks.
Moon tourists will have opportunities to observe science experiments, manufacturing processes, medical research and the workings of life-support systems.
There will be tours of the austere landscape, but the visit that almost everyone will want to make will be to the spot where Neil Armstrong and Edwin (Buzz) Aldrin in 1969 became the first representatives of the human race to set foot on the moon--and where they left a United States flag to mark the occasion.
On some of the excursions tourists will wear spacesuits that will be self-contained, single-person mobile habitations. Most excursions, however, will be conducted in vehicles with complete life-support systems for groups of tourists.
But the main attraction will be Earth-viewing, not only for its heart-stopping beauty but for the chance to view and learn about our planet in ways never before possible.
Today's Space Shuttle must bore a long, super-hot tunnel through the atmosphere until the friction of re-entry retards the craft enough to permit a landing. The moon plane will make re-entry humdrum, perhaps by using power brakes, perhaps by losing energy by skipping, like a stone on a pond, upon the surface of the atmosphere. Then its air-breathing engines will let it land just like an airplane.
Already, preliminary work is in progress in a number of countries on such a moon plane, or at least its forerunner.
The British call their space plane concept HOTOL for Horizontal Take Off and Landing. The British government has authorized two companies, British Aerospace and Rolls-Royce, to seek an international partnership to turn the concept into reality.
The American forerunner is called the X-30 and is funded by the Department of Defense, NASA and individual private manufacturers. The Defense Advanced Research Projects Agency, which manages the program, says that a prototype could fly by 1999.
The Soviets and, lately, the Japanese--the latter already having come up with artists' renditions of imagined lunar hotels--also are working toward regular moon flights.
To preview that future, think back a moment to the aerial conquest of the Pacific. The air space over the Pacific was more mysterious then than cislunar space (between Earth and the moon) is now. Flying the Pacific seemed more impossible than the project to put humans on the moon later was to appear. Newspaper, radio and newsreel accounts of the day reflected amazement, even disbelief, that the deed could be done at all.
In less than a lifetime, the impossible became the commonplace. And that's the realistic way to look at your own prospects for vacationing on the moon.