Sunday, 26 July 2015

Quotes: Report on Planet Three and Other Speculations (1972) by Arthur C. Clarke

Arthur C. Clarke
Report on Planet Three and Other Speculations
First published by Harper & Row, 1972.
Corgi edition, 1973.

In accordance with the
terms of the Clarke-Asimov Treaty,
the second-best science writer
dedicates this book to
the second-best science-fiction writer.


My first volume of speculative essays, The Challenge of the Spaceship, was published in 1959 – exactly one decade before Neil Armstrong set foot on the Moon – and has now been out of print for some years. During the sixties two other collections appeared, Profiles of the Future (1962) and Voices from the Sky (1965), and these are still available to sufficiently determined readers.

In the meantime much has happened, and I have had later thoughts on a number of subjects. Yet the events that culminated in July 1969 at Tranquility Base have not made these speculations obsolete; indeed, many of them are now even more timely than when they first appeared.

A number of the following pieces are reprinted from The Challenge of the Spaceship; with very few exceptions, the others have never appeared in book form.


In the closing years of man’s last earthbound era I ended the precursor of this book with the words:

Across the gulf of centuries, the blind smile of Homer is turned upon our age. Along the echoing corridors of time, the roar of the rockets merges now with the creak of the wind-taught rigging. For somewhere in the world today, still unconscious of his destiny, walks the boy who will be the first Odysseus of the Age of Space….

Who could have dreamed, back in 1959, that the ‘boy’ was already nearing his thirtieth birthday? But there will be other Odysseys to come….

January 1971

Report on Planet Three

[The following document, which has just been deciphered for the Interplanetary Archaeological Commission, is one of the most remarkable that has yet been discovered on Mars, and throws a vivid light upon the scientific knowledge and mental processes of our vanished neighbors. It dates from the Late Uranium (i.e., final) Age of the Martian civilization, and thus was written little more than a thousand years before the birth of Christ.

The translation is believed to be reasonably accurate, though a few conjectural passages have been indicated. Where necessary, Martian terms and units have been converted into their terrestrial equivalents for ease of understanding. – Translator.]

The recent close approach of the planet Earth has once again revived speculations about the possibility of life upon our nearest neighbor in space. This is a question which has been debated for centuries, without conclusive results. In the last few years, however, the development of new astronomical instruments has given as much more accurate information about the other planets. Though we cannot yet confirm or deny the existence of terrestrial life, we now have much more precise knowledge of conditions on Earth and can base our discussions on a firm scientific foundation.

One of the most tantalizing things about Earth is that we cannot see it when it is closest, since it is then between us and the Sun and its dark side is therefore turned toward us. We have to wait until it is a morning or evening star, and thus a hundred million or more miles away from us, before we can see much of its illuminated surface. In the telescope, it then appears as a brilliant crescent, with its single giant Moon hanging beside it. The contrast in color between the two bodies is striking; the Moon is a pure silvery-white, but the Earth is a sickly blue-green. [The exact force of the adjective is uncertain; it is definitely unflattering. ‘Hideous’ and ‘virulent’ have been suggested as alternatives. – Translator.]


Looking at these well-established facts, we can weigh the prospects for life on Earth. It must be said at once that they appear extremely poor; however, let us be open-minded and prepared to accept even the most unlikely possibilities, as long as they do not conflict with scientific laws.

The first great objection to terrestrial life – which many experts consider conclusive – is the intensely poisonous atmosphere. The presence of such large quantities of gaseous oxygen poses a major scientific problem, which we are still far from solving. Oxygen is so reactive that it cannot normally exist in the free state; on our planet, for example, it is combined with iron to form the beautiful red deserts that cover so much of the world. It is the absence of these areas which gives Earth its unpleasant greenish hue.


Even if we assume that creatures exist on Earth which can survive in so poisonous and chemically reactive an atmosphere, the presence of these immense amounts of oxygen has two other effects. The first is rather subtle, and has only recently been discovered by a brilliant piece of theoretical research, now fully confirmed by observations.

It appears that at a great altitude in the Earth’s atmosphere – some twenty or thirty miles – the oxygen forms a gas known as ozone, containing three atoms of oxygen as compared with the normal molecule’s two. This gas, though it exists in very small quantities so far from the ground, has an overwhelmingly important effect upon terrestrial conditions. It almost completely blocks the ultraviolet rays of the Sun, preventing them from reaching the surface of the planet.

This fact alone would make it impossible for the life forms we know to exist on Earth. The Sun’s ultraviolet radiation, which reaches the surface of Mars almost unhindered, is essential to our well-being and provides our bodies with much of their energy. Even if we could withstand the corrosive atmosphere of Earth, we should soon perish because of this lack of vital radiation.

The second result of the high oxygen concentration is even more catastrophic. It involves a terrifying phenomenon, fortunately known only in the laboratory, which scientists have christened ‘fire.’

Many ordinary substances, when immersed in an atmosphere like that of Earth’s and heated to quite modest temperatures, begin a violent and continuous chemical reaction which does not cease until they are completely consumed. During the process, intolerable quantities of heat and light are generated, together with clouds of noxious gases. Those who have witnessed this phenomenon under controlled laboratory conditions described it as quite awe-inspiring; it is certainly fortunate for us that it can never occur on Mars.

Yet it must be quite common on Earth – and no possible form of life could exist in its presence. Observations of the night side of Earth have often revealed bright glowing areas where fire is raging; though some students of the planet have tried, optimistically, to explain these glows as the lights of cities, this theory must be rejected. The glowing regions are much too variable; with few exceptions, they are quite short-lived, and they are not fixed in location. [These observations were doubtless due to forest fires and volcanoes – the latter unknown on Mars. It is a tragic irony of fate that had the Martian astronomers survived a few more thousand years, they would have seen the lights of man’s cities. We missed each other in time by less than a millionth of the age of our planets. – Translator.]

Its dense, moisture-laden atmosphere, high gravity and closeness to the Sun make Earth a world of violent climatic extremes. Storms of unimaginable intensity have been observed raging over vast areas of the planet, some of them accompanied by spectacular electrical disturbances, easily detected by sensitive radio receivers here on Mars. It is hard to believe that any form of life could withstand these natural convulsions, from which the planet is seldom completely free.


To sum up, therefore, it appears that our neighbor Earth is a forbidding world of raw, violent energies, certainly quite unfitted for any type of life which now exists on Mars. That some form of vegetation may flourish beneath that rain burdened, storm-tossed atmosphere is quite possible; indeed, many astronomers claim to have detected color changes in certain areas which they attribute to the seasonal growth of plants.

As for animals – this is pure speculation, all the evidence being against them. If they exist at all, they must be extremely powerful and massively built to resist the high gravity, probably possessing many pairs of legs and capable only of slow movement. Their clumsy bodies must be covered with thick layers of protective armor to shield them from the many dangers they must face, such as storms, fire, and the corrosive atmosphere. In view of these facts, the question of intelligent life on Earth must be regarded as settled. We must resign ourselves to the idea that we are the only rational beings in the Solar System.

For those romantics who still hope for a more optimistic answer, it may not be long before Planet Three reveals its last secret to us. Current work on rocket propulsion has shown that it is quite possible to build a spacecraft that can escape from Mars and head across the cosmic gulf toward our mysterious neighbor. Though its powerful gravity would preclude a landing (except by radio-controlled robot vehicles), we could orbit Earth at a low altitude and thus observe every detail of its surface from little more than a millionth of our present distance.

Now that we have at last released the limitless energy of the atomic nucleus, we may soon use this tremendous new power to escape the bonds of our native world. Earth and its giant satellite will be merely the first celestial bodies our future explorers will survey. Beyond them lie…

[Unfortunately, the manuscript ends here. The remainder has been charred beyond decipherment, apparently by the thermonuclear blast that destroyed the Imperial Library, together with the rest of Oasis City. It is a curious coincidence that the missiles which ended Martian civilization were launched at a classic moment in human history. Forty million miles away, with slightly less advanced weapons, the Greeks were storming Troy. – Translator.]

The Star of the Magi

This article was written for the December 1954 issue of Holiday magazine, but I have not changed the opening paragraph, because almost every Christmas Venus is a brilliant object either in the morning or the evening sky.

Readers of my fiction will recognize in this essay the origins of the short story ‘The Star.’[1]

[First lines:]
Where is he that is born King of the Jews? for we have seen his star in the east, and are come to worship him.

Go out of doors any morning this December and look up at the eastern sky an hour or so before dawn. You will see there one of the most beautiful sights in all the heavens – a blazing, blue-white beacon, many times brighter than Sirius, the most brilliant of the stars. Apart from the Moon itself, it will be the brightest object you will ever see in the night sky. It will still be visible even when the Sun rises; you will even be able to find it at midday if you know exactly where to look for.

It is the planet Venus, our sister world, reflecting across the gulfs of space the sunlight glancing from her unbroken cloud shield. Every nineteen months she appears in the morning sky, rising shortly before the Sun, and all who see this brilliant herald of the Christmas dawn will inevitably be reminded of the star that led the Magi to Bethlehem.

What was that star, assuming that it had some natural explanation? Could it, in fact, have been Venus? At least one book has been written to prove this theory, but it will not stand up to serious examination. To all the people in the Eastern world, Venus was one of the most familiar objects in the sky. Even today, she serves as a kind of alarm clock to the Arab nomads. When she rises, it is time to start moving, to make as much progress as possible before the Sun begins to blast the desert with its heat. For thousands of years, shining more brilliantly than we ever see her in our cloudy northern skies, she has watched the camps struck and the caravans begin to move.

Even to the ordinary, uneducated Jews of Herod’s kingdom, there could have been nothing in the least remarkable about Venus. And the Magi were no ordinary men; they were experts on astronomy, and must have known the movements of the planets better than do ninety-nine people out of a hundred today. To explain the Star of the Bethlehem we must look elsewhere.

The Bible gives us very few clues; all that we can do is to consider some possibilities which at this distance in time can be neither proved nor disproved. One of these possibilities – the most spectacular and awe-inspiring of all – has been discovered only in the last few years, but let us first look at some of the earlier theories.

In addition to Venus, there are four other planets visible to the naked eye – Mercury, Mars, Jupiter and Saturn. During their movements across the sky, two planets may sometimes appear to pass very close to one another – though in reality, of course, they are actually millions of miles apart.

Such occurrences are called ‘conjunctions’; on occasion they may be so close that the planets cannot be separated by the naked eye. This happened for Mars and Venus on October 4, 1953, when for a short while the two planets appeared to be fused together to give a single star. Such a spectacle is rare enough to be very striking, and the great astronomer Johannes Kepler devoted much time to proving that the Star of Bethlehem was a special conjunction of Jupiter and Saturn. The planets passed very close together (once again, remember, this was purely from Earth’s point of view – in reality they were half a billion miles apart!) in May, 7 B.C. This is quite near to the date Christ’s birth, which probably took place in the spring of 7 or 6 B.C. (This still surprises most people, but as Herod is known to have died early in 4 B.C., Christ must have been born before 5 B.C. We should add six years to the calendar for A.D. to mean what it says.)

Kepler’s proposal, however, is as unconvincing as the Venus theory. Better calculations than those he was able to make in the seventeenth century have shown that this particular conjunction was not a very close one, and the planets were always far enough apart to be easily separated by the eye. Moreover, there was a closer conjunction in 66 B.C., which on Kepler’s theory should have brought a delegation of wise men to Bethlehem sixty years too soon!

In any case, the Magi could be expected to be as familiar with such events as with all other planetary movements, and the Biblical account also indicates that the Star of Bethlehem was visible over a period of weeks (it must have taken the Magi a considerable time to reach Judea, have their interviews with Herod, and then go on to Bethlehem). The conjunction of two planets lasts only a very few days, since they soon separate in the sky and go once more upon their individual ways.

We can get over the difficulty if we assume that the Magi were astrologers (‘Magi’ and ‘magician’ have a common root) and had somehow deduced the birth of the Messiah from a particular configuration of the planets, which to them, if to no one else, had a unique significance. It is an interesting fact that the Jupiter-Saturn conjunction of 7 B.C. occurred in the constellation Pisces, the Fish. Now though the ancient Jews were too sensible to believe in astrology, the constellation Pisces was supposed to be connected with them. Anything peculiar happening in Pisces would, naturally, direct the attention of Oriental astrologers toward Jerusalem.

This theory is simple and plausible, but a little disappointing. One would like to think that the Star of Bethlehem was something more dramatic and not anything to do with the familiar planets whose behavior had been perfectly well known for thousands of years before the birth of Christ. Of course, if one accepts as literally true the statement that ‘the star, which they saw in the east, went before them, till it came and stood over where the young Child was,’ no natural explanation is possible. Any heavenly body – star, planet, comet, or whatever – must share in the normal movement of the sky, rising in the east and setting some hours later in the west. Only the Pole Star, because it lies on the invisible axis of the turning Earth, appears unmoving in the sky and can act as a fixed and constant guide.


Very well, then, can we discover some astronomical phenomenon sufficiently startling to surprise men completely familiar with the movements of the stars and planets and which fits the Biblical text?

Let’s see if a comet would answer the specification. There have been no really spectacular comets in this century – though there were several in the 1800s – and most people do not know what they look like or how they behave. They even confuse them with meteors, which any observer is bound to see if he goes out on a clear night and watches the sky for half an hour.

No two classes of object could be more different. A meteor is a speck of matter, usually smaller than a grain of sand, which burns itself up by friction as it tears through the outer layers of Earth’s atmosphere. But a comet may be millions of times larger than the entire Earth, and may dominate the night sky for weeks on end. A really great comet may look like a searchlight shining across the stars, and it is not surprising that such a portentous object always caused alarm when it appeared in the heavens. As Calpurnia said to Caesar:

When beggars die, there are no comets seen;
The heavens themselves blaze forth the death of princes.


It is perfectly possible that a comet appeared just before the birth of Christ. Attempts have been made, without success, to see if any of the known comets were visible around that date. […] But the number of comets whose paths and periods we do know is very small compared with the colossal number that undoubtedly exists. If a comet did shine over Bethlehem, it may not be seen again from Earth for a hundred thousand years.

We can picture it in that Oriental dawn – a band of light streaming up from the eastern horizon, perhaps stretching vertically toward the zenith. The tail of a comet always points away from the Sun; the comet would appear, therefore, like a great arrow, aimed at the east. As the Sun rose, it would fade into invisibility; but the next morning, it would be in almost the same place, still directing the travelers to their goal. It might be visible for weeks before it disappeared once more into the depths of space.

The picture is a dramatic and attractive one. It may even be the correct explanation; one day, perhaps, we shall know.

But there is yet another theory, and this is the one which most astronomers would probably accept today. It makes the other explanations look very trivial and commonplace indeed, for it leads us to contemplate one of the most astonishing – and terrifying – events yet discovered in the whole realm of nature.

We will forget now about planets and comets and the other denizens of our own tight little Solar System. Let us go out across real space, right out to the stars – those other suns, many far greater than our own, which sheer distance has dwarfed to dimensionless points of light.

Most of the stars shine with unwavering brilliance, century after century. Sirius appears now exactly as it did to Moses, as it did to Neanderthal man, as it did to the dinosaurs – if they ever bothered to look at the night sky. Its brilliance has changed little during the entire history of our Earth and will be the same a billion years from now.

But there are some stars – the so-called ‘novae,’ or new stars – which through internal causes suddenly become celestial atomic bombs. Such a star may explode so violently that it leaps a hundred-thousand-fold in brilliance within a few hours. One night it may be invisible to the naked eye; on the next, it may dominate the sky. If our Sun became such a nova, Earth would melt to slag and puff into vapor in a matter of minutes, and only the outermost of the planets would survive.

Novae are not uncommon; many are observed each year, though few are near enough to be visible except through telescopes. They are the routine, everyday disasters of the Universe.

Two or three times in every thousand years, however, there occurs something which makes a mere nova as inconspicuous as a firefly at noon. When a star becomes a supernova, its brilliance may increase not by a hundred thousand but by a billion in the course of a few hours. The last time such an event was witnessed by human eyes was in A.D. 1604; there was another supernova in A.D. 1572 (so brilliant that it was visible in broad daylight); and the Chinese astronomers recorded one in A.D. 1503. It is quite possible that the Bethlehem star was such a supernova, and if so one can draw some surprising conclusions.

We’ll assume that Supernova Bethlehem was about as bright as the supernova of A.D. 1572 – often called ‘Tycho’s star,’ after the great astronomer who observed it at the time. Since this star could be seen by day, it must have been as brilliant as Venus. As we also know that a supernova is, in reality, at least a hundred million times more brilliant than our own Sun, a very simple calculation tells us how far away it must have been for its apparent brightness to equal that of Venus.   

It turns out that Supernova Bethlehem was more than three thousand light years – or, if you prefer, 18 quadrillion miles – away. That means that its light had been traveling for at least three thousand years before it reached Earth and Bethlehem, so that the awesome catastrophe of which it was the symbol took place five thousand years ago, when the Great Pyramid was still fresh from the builders.

Let us, in imagination, cross the gulfs of space and time and go back to the moment of the catastrophe. We might find ourselves watching an ordinary star – a sun, perhaps, no different from our own. There may have been planets circling it; we do not know how common planets are in the scheme of the Universe, and how many suns have these small companions. But there is no reason to think that they are rare, and many novae must be the funeral pyres of worlds, and perhaps races, greater than ours.

There is no warning at all – only a steadily rising intensity of the sun’s light. Within minutes the change is noticeable; within an hour, the nearer worlds are burning. The star is expanding like a balloon, blasting off shells of gas at a million miles an hour as it blows its outer layers into space. Within a day, it is shining with such supernal brilliance that it gives off more light than all the other suns in the Universe combined. If it had planets, they are now no more than flecks of flame in the still-expanding shells of fire. The conflagration will burn for weeks before the dying star collapses back into quiescence.

But let us consider what happens to the light of the nova, which moves a thousand times more swiftly than the blast wave of the explosion. It will spread out into space, and after four or five years it will reach the next star. If there are planets circling that star, they will suddenly be illuminated by a second sun. It will give them no appreciable heat, but will be bright enough to banish night completely, for it will be more than a thousand times more luminous than our full Moon. All that light will come from a single blazing point, since even from its nearest neighbor Supernova Bethlehem would appear too small to show a disk.

Century after century, the shell of light will continue to expand around its source. It will flash past countless suns and flare briefly in the skies of their planets. Indeed, on the most conservative estimate, this great new star must have shone over thousands of worlds before its light reached Earth – and to all those worlds it appeared far, far brighter than it did to the men it led to Judea.

For as the shell of light expanded, it faded also. Remember, by the time it reached Bethlehem it was spread over the surface of a sphere six thousand light-years across. A thousand years earlier, when Homer was singing the song of Troy, the nova would have appeared twice as brilliant to any watchers further upstream, as it were, to the time and place of the explosion.

That is a strange thought; there is a stranger one to come. For the light of Supernova Bethlehem is still flooding out through space; it has left Earth far behind in the twenty centuries that have elapsed since men saw it for the first and last time. Now that light is spread over a sphere ten thousand light-years across and must be correspondingly fainter. It is simple to calculate how bright the supernova must be to any beings who may be seeing it now as a new star in their skies. To them, it will still be far more brilliant than any other star in the entire heavens, for its brightness will have fallen only by 50 per cent on its extra two thousand years of travel.

At this very moment, therefore, the Stat of Bethlehem may still be shining in the skies of countless worlds, circling far suns. Any watchers on those worlds will see its sudden appearance and its slow fading, just as the Magi did two thousand years ago when the expanding shell of light swept past the Earth. And for thousands of years to come, as its radiance ebbs out toward the frontiers of the Universe, Supernova Bethlehem will still have power to startle all who see it, wherever – and whatever – they may be.

Astronomy, as nothing else can do, teaches men humility. We know now that our Sun is merely an undistinguished member of a vast family of stars, and no longer think of ourselves as being at the center of creation. Yet it is strange to think that before its light fades away below the limits of vision, we may have shared the Star of Bethlehem with the beings of perhaps a million worlds – and that to many of them, nearer to the source of explosion, it must have been a far more wonderful sight than ever it was to any eyes on earth.

What did they make of it – and did it bring them good tidings, or ill?

Vacation in Vacuum[2]

This essay was commissioned by Holiday magazine in 1953 – four years before Sputnik 1. At the time, most readers must have thought that orbiting hotels were the wildest of fantasy, but now Barron Hilton firmly expects to be running such establishments before the year 2001 dawns. 

And talking of 2001 (as we shall be) here is the original inspiration of the space-station sequence in the movie; Stanley Kubrick constructed the ‘Sky Grill,’ full-sized, at M-G-M’s Borehamwood Studios.

I must confess that I now have my doubts about the practicability – and stability – of the spherical swimming pool; but a hollow cylindrical one could certainly be built, and would be just as much fun.

When the United States and the U.S.S.R. started building the first satellite stations, back in the 1960s, the idea that they would one day become health resorts and embarkation points for spacebound vacationers would have seemed slightly fantastic. Yet it was no more fantastic, of course, than the fact that since the beginning of the century the human race had deserted the sea and lifted its commerce into the air. If anyone had dared to prophesy that miracle when the Wright Brothers made their first nervous hop in 1903, he would have been laughed to scorn. And even fifty years later, though there were many who realized that space stations might have military and scientific uses, there were very few who looked beyond these to the day when they would become part of everyday life.

Well, perhaps that is a slight exaggeration. Even today, relatively few people have actually been to a space station, but there can be nobody who has not seen one with his own eyes. If you live near the equator you have a fine selection to choose from: you can see not only the outer stations but the close refueling satellites that hug the edge of the atmosphere and are so near the Earth that the curve of the planet hides them from observers at high latitudes. In the daytime they are bright stars, easily visible when the sky is clear, sweeping from horizon to horizon in a matter of minutes. And, of course, they move backward, from west to east, because they race around their tight little orbits so much more quickly than the Earth itself turns on its axis.


Let’s go up there into the shining darkness of space, into that paradoxical world where intense heat and unimaginable cold exist together, where dawn and dusk are separated by minutes, not by hours.


By the end of the twentieth century there were dozens of military reconnaissance units, meteorological stations, and astronomical observations circling the Earth at various distances, carrying crews of up to twenty men in conditions almost as cramped as in the old-time submarines. They were the first forerunners of the spacious orbital cities we have today – the nuclei around which the later satellites were built, just as on Earth itself great capitals once grew from ancient villages or fortified camps.

The ordinary space traveler sees only the inner station – Space Station One – as he transfers from the Earth ferry rocket to the liner that’s taking him to Mars or Venus. It’s the nearest of all the satellites, a mere three hundred miles up – too close, therefore, to give one a really good view of Earth. If you want to see the planet as a whole, you’ve got to travel out to one of the more distant stations. We’ll start our tour, therefore, more than ten thousand miles out, in the most luxurious of all the satellites – Sky Hotel.


The hotel is in two sections – the part with gravity and the part without. When you first see it from your approaching rocket, you’ll think you’re about to land on the planet Saturn. Hanging there in space ahead of you is a great ball, with a ring surrounding it but not touching it at any point. The ball is motionless, while the ring slowly revolves.

When the pilot has jockeyed the rocket over to the ball, you’ll realize just how big the hotel is. Your ship will seem like a toy when it couples itself up to the mooring socket on the axis of the station and the air locks are joined together so that you can go aboard. The hotel staff will collect both you and your luggage, for most people are pretty helpless under zero gravity for the first few hours. But, believe me, it’s an experience worth getting used to.

Sky Hotel has, by ingenious design, managed to get the best of both worlds. Most vacationers go up there to enjoy the fun and games under zero-gee, but weightlessness is not so amusing when you want to eat a meal or take a bath, and some people find it impossible to sleep under free-fall conditions. Hence the dual-purpose design of the hotel. The central hall contains the gymnasiums and that fantastic swimming pool we’ll be visiting presently, while over in the ring are the bedrooms, lounges, and restaurant. As the ring rotates, centrifugal force gives everyone inside it a feeling of weight which can’t be distinguished from the real thing. It’s not so powerful, though – at the outer rim of the hotel you’ll weigh only half as much as you would on Earth.


Most of the hotel’s residents divide their time more or less equally between the gee and the zero-gee parts – between the ring and the ball, in other words. The kids are an exception. It’s a job luring them away from weightlessness, even for meals, so they spend almost all their time in the ball. There is a snack bar over there, where you can get drinks served in plastic bulbs so that you can squirt the liquid straight into your mouth. That’s the theory – and it works, too. But the kids usually prefer less efficient methods, and promptly empty their bulbs into the air. It’s quite a sight watching a budding space cadet chasing a ball of Coke as it drifts slowly from point to point and eventually splatters messily on one of the walls.

Traveling between the stationary ball and the spinning ring that surrounds it is another of the novelties of space-station life. The trip is made in a kind of pressurized elevator cage, running around a track on the inside of the ring. It’s a queer sensation, feeling your weight ebb away as you move across to the ball and centrifugal force vanishes.


However, since there’s little point in going out into space to indulge in terrestrial-type sports, most of the excess energy in Sky Hotel is expended in the zero-gee rooms aboard the ball. The one thing that nobody misses is a chance to do some flying – real flying, of the kind we’ve all dreamed about at some time or another. You may feel a little foolish as you fasten the triangular wings between your ankles and wrists and secure the free ends to your belt. Certainly your first few strokes will start you turning helplessly over and over in the air. But in a few hours you’ll be flying like a bird – and much more effortlessly. By the way, the crash helmet that goes with the wings is not just an ornament. It may prevent your knocking yourself out if you get up too much speed and don’t notice how near the wall you are.

Some of the zero-gee ballets, with special lightning effects, that the expert performers can execute are unbelievably beautiful, like fairyland filmed in slow motion. Even if you’ve already seen them on TV, don’t miss an opportunity to attend an actual performance at the hotel.

When you’ve earned your wings in the amusing series of tests that entitles you to your ‘Spacehound’s Certificate,’ you’ll probably want to take part in such sports as zero-gee basketball or three-dimensional miniature golf. Many terrestrial games have been adapted, with interesting variations, to conditions of weightlessness, but there are also dozens of sports and tricks that have no counterpart on Earth.

For example, there’s the quite exhausting game you can play where everyone puts on wings and the winner is the one who can collect the largest number of scattered water drops into a single sphere – and bring it back to goal before his opponents tear it to pieces.

Talking of water drops leads me, inevitably, to the hotel’s most incredible novelty – its famous swimming pool. Any resemblance to similarly described places on Earth is not merely coincidental – it’s nonexistent.

When you go to the ‘pool’ you’ll find yourself in a big spherical chamber about sixty feet across, almost filled by what is claimed – probably correctly – to be  the largest single drop of water in existence. You won’t be particularly surprised to see people swimming around and around inside the sphere, but what will astonish you is the sight of a group in its center talking and laughing together and perhaps even taking refreshments. Even in space, you’ll say to yourself, people still have to breathe!

To settle the mystery, dive into the drop and swim through it. When you’ve gone about twenty feet and are still some distance from the center, you’ll break through another water surface and find yourself in a hollow space about ten feet across, breathing ordinary air. Yes, you’re inside a bubble! It can’t escape from the inside of the drop, because only when there is an ‘up’ can bubbles rise in liquid. So the swimming pool is really a huge hollow shell of water and you can sit quietly at the very center and watch your friends sporting like fish around you.


When you’re tired of swimming, you can spend a good many happy hours in the observation lounge, simply watching the Earth and stars. There are no windows in the ring, because it would be rather disconcerting to see the heavens around you revolting at such a rate. So you’ll have to do all your stargazing from the nonrotating ball.

From ten thousand miles out, the Earth is just small enough to fill your field of vision completely, and you can see everything except the extreme polar regions. Even to the naked eye, it’s a source of endless enchantment. In the nine hours that the hotel takes to complete its orbit, you’ll see the Earth change from new to full and back again, going through the phases that the Moon takes a whole month to complete. The sight of the dawn down there, as the Sun comes blasting up through the incandescent mists at the edge of the atmosphere and Earth grows swiftly from a hairline crescent to a huge glowing disk, is something no amount of repetition can stale.

When you’ve had your fill of gazing through the observation windows, you’ll turn to the telescopes. Some of them can magnify up to a thousand times, so you’ll feel that you’re hanging only ten miles above the surface of the Earth. If there’s no cloud, it’s amazing how much minute detail you can see. Towns and cities are easy; even single large buildings can be detected under favorable conditions. But don’t believe anyone who tells you that they’ve been able to see individual men! That’s only possible from the inner satellites, a mere few hundred miles up.

It’s interesting to study the effect of these novel surroundings on your companions. Human beings are incredibly adaptable, and for most of the time the guests in Sky Hotel enjoy themselves in the same uninhibited way as if they were down on Earth. But from time to time you’ll catch them looking thoughtfully at the stars, realizing that this is space, this is the Universe. They’ll have become suddenly aware that the familiar Earth, with its gravity and its air and its oceans, and its teeming, multitudinous life, is a freak, an incredible rarity; 99.999999… per cent of the cosmos is emptiness and night.

That realization can affect people in two ways. It can depress them when they think how puny man is against the Universe, or it can exhilarate them when they consider his courage in attempting to conquer it.

Moving in almost exactly the same orbit as the hotel, but fifty miles away from it, is the newest and largest of the space hospitals – Haven IV. It’s often possible to arrange a trip across in one of the low-powered rocket shuttles that ply between the orbits of the various stations, and sometimes there are official conducted tours of the hospital. Most of the patients on Haven are heart cases, recuperating under conditions where physical effort is much less than on Earth and their weakened hearts haven’t got to pump pounds of blood up and down the body twenty-four hours a day.


Besides the heart cases, the space hospitals specialize in polio victims, as well as people who have lost their legs and would be virtually helpless down on Earth. There are quite a number of legless men working permanently on the space stations. Often they are more agile than those who are not disabled – they haven’t so much useless mass to drag around!

Quite recently, Haven IV has started to deal with severe burns. It doesn’t take much imagination to realize how treatment and recuperation can be speeded when the patient can float freely in space and no longer has to lie on his dressings.


You may feel rather superior to these lower satellites as you look down upon them from your ten-thousand-mile-high eyrie. But if you do, then remember that the outermost of all Earth’s man-made moonlets are twelve thousand miles beyond you. I mean, of course, the three relay stations which now carry all long-range TV and radio traffic of the planet.


Sometimes you can thumb a lift on a shuttle up to one of the relay stations. Out there, more than twenty thousand miles above the Earth, you’ll really feel you’re on the frontier of space. But don’t forget that this is only a tenth of the distance to our nearest neighbor, the Moon, and much less than a thousandth of the distance to Mars or Venus, even at their closest approach. So when you get back to Earth, don’t be too boastful about your achievements – at least until you’ve made quite sure that there are no real spacehounds in the party.

More seriously, there’s one point you must watch when you’re home again. Take things very easily for the first few days. Remember, we’ve got a little thing called gravity down here, and the tricks you can play in Sky Hotel won’t work so well back on Earth. You can’t cross Fifth Avenue, for instance, by stepping out at the two hundredth floor of Planet Tower and launching yourself in an easterly direction. (Take my word for it – it’s been tried.) Even in your own house, you may find yourself treating the stairs with quite unjustified contempt, so this warning is by no means as superfluous as it seems.

So You’re Going to Mars?

This essay was written in 1952, long before the Mariner space probes gave us our close-up glimpses of the tantalizing red planet. Nevertheless, most of the concepts presented here are still quite valid, though we now know that Mars is even more rugged than anticipated. In particular, the atmospheric pressure is so low (about one-hundredth of Earth’s) that simple breathing masks will not give sufficient protection; we will have to wear spacesuits.

Many of the ideas in this article were worked out in much more detail in my novel The Sands of Mars.

So you’re going to Mars? That’s still quite an adventure – though I suppose that in another ten years no one will think twice about it. Sometimes it’s hard to remember that the first ships reached Mars scarcely more than half a century ago and that our colony on the planet is less than thirty years old. (By the way, don’t use that word when you get there. Base, settlement, or what you like – but not colony, unless you want to hear the ice tinkling all around you.)

I suppose you’ve read all the forms and tourist literature they gave you at the Department of Extraterrestrial Affairs. But there’s a lot you won’t learn just by reading, so here are some pointers and background information that may make your trip more enjoyable. I won’t say it’s right up to date – things change so rapidly, and it’s a year since I got back from Mars myself – but on the whole you’ll find it pretty reliable.

Presumably you’re going just for curiosity and excitement – because you want to see what life is like out on the new frontier. It’s only fair, therefore, to point out that most of your fellow passengers will be engineers, scientists, or administrators traveling to Mars – some of them not for the first time – because they’ve got a job of work to do. So whatever your achievements here on Earth, it’s advisable not to talk too much about them, as you’ll be among people who’ve had to tackle much tougher propositions. I won’t say that you’ll find them boastful: it’s simply that they’ve got a lot to be proud of, and they don’t mind who knows it.


You’re probably wondering how you can possibly manage on the weight allowance you’ve got. Well, it can be done. The first thing to remember is that you don’t need to take any suits. There’s no weather inside a spaceship; the temperature never varies more than a couple of degrees over the whole trip, and it’s held at a fairly high value so that all you’ll want is an ultra-lightweight tropical kit. When you get to Mars you’ll buy what you need there and dump it when you return. The great thing to remember is only carry the stuff you actually need on the trip. I strongly advise you to buy one of the complete travel kits – a store like Abercrombie & Fitch can supply the approved outfits. They’re expensive, but will save you money on excess baggage charges.

Take camera by all means – there’s a chance of some unforgettable shots as you leave Earth and when you approach Mars. But there’s nothing to photograph on the voyage itself, and I’d advise you to take all your pictures on the outward trip. You can sell a good camera on Mars for five times its price here – and save yourself the cost of freighting it home. They don’t mention that in the official handouts.


So much for the preliminaries; now some points about the trip itself. The ferry rocket will probably leave from the New Guinea field, which is about two miles above sea level on the top of the Orange Range. People sometimes wonder why they chose such an out-of-the-way spot. That’s simple: it’s on the equator, so the ship gets the full thousand-mile-an-hour boost of the Earth’s spin as it takes off – and there’s the whole width of the Pacific for jettisoned fuel tanks to fall into. And if you’ve ever heard a spaceship taking off, you’ll understand why launching sites have to be a few hundred miles from civilization.

Don’t be alarmed by anything you’ve been told about the strain of blast-off. There’s really nothing to it if you’re in good health – and you won’t be allowed inside a spaceship unless you are. You just lie down on the acceleration couch, put in your earplugs, and relax. It takes over a minute for the full thrust to build up, and by that time you’re quite accustomed to it. You’ll have some difficulty in breathing, perhaps – it’s never bothered me – but if you don’t attempt to move you’ll hardly feel the increase of weight. What you will notice is the noise, which is slightly unbelievable. Still, it lasts only five minutes, and by the end of that time you’ll be up in the orbit and the motors will cut out. Don’t worry about your hearing; it will get back to normal in a couple of hours.


Space Station One, which is where the ferries and the liners meet to transfer their cargoes, takes just two hours to make one circuit of the Earth. You’ll spend all your time in the observation lounge: everyone does, no matter how many times they’ve been out in space. I won’t attempt to describe that incredible view; I’ll merely remind you that in the hundred and twenty minutes it takes the station to complete its orbit you’ll see the Earth wax from a thin crescent to a gigantic, multicolored disc, and then shrink again to a black shield eclipsing the stars. As you pass over the night side you’ll see the lights of cities down there in the darkness, like patches of phosphorescence. And the stars! You’ll realize that you’ve never seen them before in your life.

But enough of these purple passages; let’s stick to business. You’ll probably remain on Space Station One for about twelve hours, which will give you plenty of opportunity to see how you like weightlessness. It doesn’t take long to learn how to move around; the main secret is to avoid all violent motions – otherwise you may crack your head on the ceiling. Except, of course, that there isn’t a ceiling since there’s no up or down anymore. At first you’ll find this confusing: you’ll have to stop and decide which direction you want to move in, and then adjust your personal reference system to fit. After a few days in space it will be second nature to you.

Don’t forget that the station is your last link with Earth. If you want to make final purchases, or leave something to be sent home – do it then. You won’t have another chance for a good many million miles. But beware of buying items that the station shop assures you are ‘just the thing on Mars.’


If you’re on one of the larger liners, there’ll be about a hundred other passengers and a crew of perhaps twenty. You’ll get to know them all by the end of the voyage. There’s nothing on Earth quite like the atmosphere of a spaceship. You’re a little, self-contained community floating in vacuum millions of miles from anywhere, kept alive in a bubble of plastic and metal. If you’re a good mixer, you’ll find the experience very stimulating. But it has its disadvantages. The one great danger of space flight is that some prize bore may get on the passenger list – and short of pushing him out of the air lock there’s nothing anyone can do about it.


Unlike the take-off of the ferry rocket from Earth, the breakaway of the liner from its satellite orbit is so gentle and protracted that it lacks all drama. When the loading and instrument checks have been completed, the ship will uncouple from the Space Station and drift a few miles away. You’ll hardly notice it when the atomic drive goes on; there will be the faintest of vibrations and a feeble sensation of weight. The ship’s acceleration is so small, in fact, that you’ll weigh only a few ounces, which will scarcely interfere with your freedom of movement at all. Its only effect will be to make things drift slowly to one end of the cabin if they’re left lying around.

Although the liner’s acceleration is so small that it will take hours to break away from Earth and head out into space, after a week of continuous drive the ship will have built up a colossal speed. Then the motors will be cut out and you’ll carry on under your own momentum until you reach the orbit of Mars and have to start thinking about slowing down.

Whether your weeks in space are boring or not depends very much on you and your fellow passengers. Quite a number of entertainments get organized on the voyage, and a good deal of money is liable to change hands before the end of the trip. (It’s a curious fact, but the crew usually seems to come out on top.) You’ll have plenty of time for reading, and the ship will have a good library of microbooks. There will be radio and TV contact with Earth and Mars for the whole voyage, so you’ll be able to keep in touch with things – if you want to.

On my first trip, I spent a lot of my time learning my way around the stars and looking at clusters and nebulae through a small telescope I borrowed from the navigation officer. Even if you’ve never felt the slightest interest in astronomy before, you’ll probably be a keen observer before the end of the voyage. Having the stars all around you – not merely overhead – is an experience you’ll never forget.


The braking period doesn’t last very long, as the ship has lost a good deal of its speed in the climb outward from the Sun. When it’s over you’ll be dropping down onto Phobos, the inner moon of Mars, which acts as a natural space station about four thousand miles above the surface of the planet. Though Phobos is only a jagged lump of rock not much bigger than some terrestrial mountains, it’s reassuring to be in contact with something solid again after so many weeks in space.


You’ll land, of course, at Port Lowell: besides being the largest settlement on Mars it’s still the only place that has the facilities for handling spaceships. From the air the plastic pressure domes look like a cluster of bubbles – a very pretty sight when the Sun catches them. Don’t be alarmed if one of them is deflated. That doesn’t that there’s been an accident. The domes are let down at fairly frequent intervals so that the envelopes can be checked for leaks. If you’re lucky you may see one being pumped up – it’s quite impressive.

After two months in a spaceship, even Port Lowell will seem a mighty metropolis. (Actually, I believe its population is now well over twenty thousand.) You’ll find the people energetic, inquisitive, forthright – and very friendly, unless they think you’re trying to be superior.

It’s a good working rule never to criticize anything you see on Mars. As I said before, they’re very proud of their achievements – and after all you are a guest, even if a paying one.


You shouldn’t attempt to leave the city until you’ve become quite accustomed to living in an oxygen-rich, low-pressure atmosphere. You’ll have grown pretty well acclimatized on the trip, because the air in the spaceship will have been slowly adjusted to conditions on Mars. Outside the domes, the pressure of the natural Martian atmosphere is about equal to that on the top of Mount Everest – and it contains practically no oxygen. So when you go out you’ll have to wear a helmet, or travel in one of those pressurized jeeps they call ‘sand fleas.’


Don’t attempt to imitate any of the locals you may see walking around without oxygen gear. They’re second-generation colonists and are used to the low pressure. They can’t breathe the Martian atmosphere any more than you can, but like the old-time native pearl divers they can make one lungful last for several minutes when necessary. Even so, it’s a silly sort of trick and they’re not supposed to do it.


No doubt you’ll want to see as much of Mars as you can during your stay. There are only two methods of transport outside the cities – sand fleas for short ranges and aircraft for longer distances. Don’t misunderstand me when I say ‘short ranges’ – a sand flea with a full charge of power cells is good for a couple of thousand miles, and it can do eighty miles an hour over good ground. Mars could never have been explored without them. You can survey a planet from space, but in the end someone with a pick and shovel has to do the dirty work filling the map.

One thing that few visitors realize is just how big Mars is. Although it seems small beside the Earth, its land area is almost as great because so much of our planet is covered with oceans. So it’s hardly surprising that there are vast regions that have never been properly explored, particularly around the poles. Those stubborn people who still believe that there was once an indigenous Martian civilization pin their theories on these great blanks. Every so often you hear rumors of some wonderful archaeological discovery in the wastelands, but nothing ever comes of it.

Personally, I don’t believe there ever were any Martians – but the planet is interesting enough for its own sake. You’ll be fascinated by the plant life and the queer animals that manage        to live without oxygen, migrating each year from hemisphere to hemisphere, across the ancient sea beds, to avoid the ferocious winter. The fight for survival on Mars has been fierce, and evolution has produced some pretty odd results. Don’t go investigating any Martian life forms unless you have a guide, or you may get some unpleasant surprises. Some of the plants are so hungry for heat that they may try to wrap themselves around you.

God and Einstein

For some years I have been worried by the following astro-theological paradox. It is hard to believe that no one has ever thought of it, yet I have never seen it discussed anywhere.

One of the most firmly established facts of modern physics, and the basis of Einstein’s Theory of Relativity, is that the velocity of light is the speed limit of the material universe. No object, no signal, no influence, can travel any faster than this. Please don’t ask why this should be; the Universe just happens to be built that way. Or so it seems at the moment.

But light take not millions, but billions, of years to cross even the part of Creation we can observe with out telescopes. So: if God obeys the laws He apparently established, at any given time He can have control over only an infinitesimal fraction of the Universe. All hell might (literally?) be breaking loose ten light-years away, which is a mere stone’s throw in interstellar space, and the bad news would take at least ten years to reach Him. And then it would be another ten years, at least, before He could get there to do anything about it….

You may answer that this is terribly naïve – that God is already ‘everywhere.’ Perhaps so, but that really comes to the same thing as saying that His thoughts, and His influence, can travel at an infinite velocity.[3] And in this case, the Einstein speed limit is not absolute; it can be broken.

The implications of this are profound. From the human viewpoint, it is no longer absurd – though it may be presumptuous – to hope that we may one day have knowledge of the most distant parts of the universe. The snail’s pace of the velocity of light need not be an eternal limitation, and the remotest galaxies may one day lie within our reach.

But perhaps, on the other hand, God Himself is limited by the same laws that govern the movements of electrons and protons, stars and spaceships. And that may be the cause of our troubles.

He’s coming just as quickly as He can, but there’s nothing that even He can do about that maddening 186,000 miles a second.

It’s anybody’s guess whether He’ll be here in time.

[1] One of Arthur’s most famous short stories, first published in Infinity Science Fiction, November 1955, later reprinted in many of his collections, for instance The Other Side of the Sky (1958), The Nine Billion Names of God (1967) and The Best of Arthur C. Clarke, 1937-1971 (1973), and countless anthologies, including The Hugo Winners (1962), ed. Isaac Asimov (1956, Best Short Story). Online text.
[2] This and the next essay/story should be read as companion pieces to “Journey by Earthlight”. For more information on this trinity of tourist brochures, see note 4 in the selection of quotes from The Challenge of the Spaceship (1959).
[3] Cf. “The Challenge of the Spaceship” from the eponymous collection (1959):

But if the Universe does hold species so greatly in advance of our own, then why have they never visited Earth? There is one very simple answer to this question. Let us suppose that such races exist: let us even suppose that, never having heard of Einstein, they can pass from one end of the Galaxy to the other as quickly as they wish.

That will help them less than one might think. In ten minutes, a man may walk along a beach – but in his whole lifetime he could not examine every grain of sand upon it. For all that we know, there may be fleets of survey ships diligently charting and recharting the Universe. Even making the most optimistic assumptions, they could scarcely have visited our world in the few thousand years of recorded history.

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