As the door of the little pilot room clicked open behind me I half turned from my position at the controls, to see my two companions enter. And as the Arcturian and Capellan stepped over to my side I nodded toward the broad fore-window.
"Two more hours and we'll be there," I said.
Side by side we three gazed ahead. About us once more there stretched the utter blackness of the great void, ablaze with its jeweled suns. Far behind shone the brilliant white star that was Canopus, and to our right the great twin suns of Castor and Pollux, and above and beyond them the yellow spark that was the sun of my own little solar system. On each side and behind us hung the splendid starry canopy, but ahead it was blotted out by a single vast circle of glowing light that filled the heavens before us, titanic, immeasurable, the mighty nebula that was our goal.
For more than ten days we had watched the vast globe of flaming gas largening across the heavens as we raced on toward it, in the heat-resistant cruiser that had been furnished us by the Council. Days they were in which our generators had hummed always at their highest power, propelling our craft forward through space with the swiftness of thought, almost-long, changeless days in which the alternate watches in the pilot room and the occasional inspection of the throbbing generators had formed our only occupations.
On and on and on we had flashed, past sun after sun, star system after star system. Many times we had swerved from our course as our meteorometers warned us of vast meteor swarms ahead, and more than once we had veered to avoid some thundering dark star which our charts showed near us, but always the prow of our craft had swung back toward the great nebula. Ever onward toward it we had raced, day after day, watching its glowing sphere widen across the heavens, until now at last we were drawing within sight of our journey's end, and were flashing over the last few billions of miles that separated us from our goal.
And now, as we drew thus nearer toward the nebula's fiery mass, we saw it for the first time in all its true grandeur. A vast sphere of glowing light, of incandescent gases, it flamed before us like some inconceivably titanic sun, reaching from horizon to horizon, stunning in its very magnitude. Up and outward from the great fiery globe there soared vast tongues of flaming gas, mighty prominences of incalculable length, leaping out from the gigantic spinning sphere. For the sphere, the nebula, was spinning. We saw that, now, and could mark the turning of its vast surface by the position of those leaping tongues, and though that turning seemed slow to our eyes by reason of the nebula's very vastness, we knew that in reality it was whirling at a terrific rate.
For a long time there was silence in the little pilot room while we three gazed ahead, the glowing light from the vast nebula before us beating in through the broad window and illuminating all about us in its glare. At last Sar Than, beside me, spoke.
"One sees now why no interstellar ship has ever dared to approach the nebula," he said, his eyes on the colossal sea of flame before us.
I nodded at the Arcturian's comment. "Only our own ship would dare to come as close as we are now," I told him. "The temperature outside is hundreds of degrees, now." And I pointed toward a dial that recorded the outside heat.
"But how near can we go to it?" asked Jor Dahat. "How much heat can our cruiser stand?"
"Some thousands of degrees," I said, answering the plant-man's last question first. "We can venture within a few thousand miles of the nebula's surface without danger, I think. But if we were to go farther, if we were to plunge into its fires, even our ship could not resist the tremendous heat there for long, and would perish in a few minutes. We will be able, though, to skim above the surface without danger."
"You plan to do that, to search above the nebula's surface for the forces that have set it spinning?" asked the Capellan, and I nodded.
"Yes. There may be great ether-currents of some kind there which are responsible for this spin, or perhaps other forces of which we know nothing. If we can only find what is causing it, there will be at least a chance-" And I was silent, gazing thoughtfully toward the far-flung raging fires ahead.
* * *
Now, as our ship raced on toward that mighty ocean of flaming gas, the pointer on the outside-heat dial was creeping steadily forward, though the ship's interior was but slightly warmer, due to the super-insulation of its walls. We were passing into a region of heat, we knew, that would have destroyed any ship but our own, and that thought held us silent as our humming craft raced on. And now the sky before us, a single vast expanse of glowing flame, was creeping downward across our vision as the cruiser's bow swung up. Minutes more, and the whole vast flaming nebula lay stretched beneath us, instead of before us, and then we were dropping smoothly down toward it.
Down we fell, my hand on the control lever gradually decreasing our speed, now moving at a single lightspeed, now at half of that, and still slower and slower, until at last our craft hung motionless a scant thousand miles above the nebula's flaming surface, a tiny atom in size compared to the colossal universe of the fire above which it hovered. For from horizon to horizon beneath us, now, stretched the nebula, in terrible grandeur. Its flaming sea, we saw, was traversed by great waves and currents, currents that met here and there in gigantic fiery maelstroms, while far across its surface we saw, now and then, great leaping prominences of geysers of flaming gas, that towered for an instant to immense heights and then rushed back down into the fiery sea beneath. To us, riding above that burning ocean, it seemed at that moment that in all the universe was only flame and gas, so brain-numbing was the fiery nebula's magnitude.
Hanging there in our little cruiser we stared down at it, the awe we felt reflected in each other's eyes. I saw now by the dial that the temperature about us was truly terrific, over a thousand degrees, and what it might be in the raging fires below I could not guess. But nowhere was there any sign of what might have set the great nebula to spinning, for our instruments recorded no ether-disturbances around the surface, nor any other phenomena which might give us a clue. And, looking down, I think that we all felt, indeed, that nothing was in reality capable of affecting in any way this awesome nebula, the vastest thing in all our universe.
At last I turned to the others. "There's nothing here," I said. "Nothing to show what's caused the nebula's spinning. We must go on, across its surface-"
With the words I reached forward toward the control levers, then abruptly whirled around as there came a sudden cry from Sar Than, at the window.
"Look!" cried the Arcturian, pointing down through the window, his eyes staring. "Below us-look!"
I gazed down, then felt the blood drive from my heart at what I saw. For directly beneath us one of the vast prominences of flaming gas was suddenly shooting up from the nebula's surface, straight toward us, a gigantic tongue of fire beside which our ship was but as a midge beside a great blaze. I shouted, sprang to the control, but even as I laid hands on the levers there was a tremendous rush of blinding flame all about our ship, and then we three had been flung violently into a corner of the pilot room and the cruiser was being whirled blindly about with lightning speed by the vast current of flaming gas that had gripped it.
All about us was the thunderous roaring of the fires that held us, and now as we sprawled helpless on the room's floor I sensed that our ship was falling, plunging down with the downward-sinking geyser of flame that held it. Struggling to gain my feet, while the pilot room spun dizzily about me, I glimpsed through the shifting fires outside the window the nebula's flaming surface, just below us, a raging sea of fiery gas toward which we were dropping plummet-like. Then, as a fresh gyration of the plunging ship flung me once more to the floor, I heard the thundering roar about us suddenly intensified, terrible beyond expression, while now through the window was visible only a single solid mass of blinding flame, and while our cruiser at the same moment rocked and whirled crazily beneath the impetus of a dozen different forces. And as understanding of what had happened flashed across my brain I cried out hoarsely to my two companions.
"The nebula!" I cried. "The current that held us has sucked us down into the nebula itself!"
All about us now was only one tremendous sheet of fire, whose heat was rapidly penetrating through even our heat-resistant walls and windows. Swiftly the air in the little pilot room was becoming hot, suffocating, and already the walls were burning to the touch. The ship, I knew, could not stand such heat for many minutes more, yet every moment was taking us farther into the nebula's fiery depths, whirling us wildly on with velocity inconceivable. Borne by its mighty interior currents we were sweeping on and on into that universe of flame, its vast fires roaring about us like the thunder of doom, deafening, awful, a cosmic, bellowing clamor that was like the mighty shouting of a universe made vocal.
On and on it roared, about us, and on and on we whirled into the depths of those mighty fires, toward our doom. The air had become stifling, unbreathable, and the walls were beginning to glow dully. Now, with a last effort, I dragged myself from support to support until I had clutched the control levers, opening them to the last notch. Yet though the generators beneath hummed with highest power it was as though they were silent, for in the grip of the nebula's giant fire-currents the cruiser plunged madly on. And as its whirling catapulted me again to the room's corner, where my two companions clung, I felt my lungs scorching with each panting breath, felt my senses leaving me.
Then, through the unconsciousness that was creeping upon me, I heard a grating wrench from somewhere in the cruiser's walls, a loud and ominous cracking, and knew that under the terrific fires around us those walls were already warping, giving way. Another wrenching crack came, and another, sounding loud in my ears above the thunderous roar of the flames about us. In a moment the walls would give completely, and in the rushing fires of the nebula about us we would meet the end. In a moment-
But what was that? The thunderous clamor about us had suddenly dwindled, ceased, and at the same moment our ship had righted itself, was humming serenely on. Slowly I raised my head, then stared in utter astonishment. The fires outside the windows, the terrific sea of flame about us, had vanished, and we were again flashing on through open space. And now Jor Dahat beside me had seen also, and was rising to his feet.
"We're out of the nebula!" he cried. "That current must have taken us back up to the surface-back out into space again-"
He was at the window now, gazing eagerly out, while I struggled up in turn. And as I did so I saw awe falling upon his face as he gazed, and heard from him a whispered exclamation of utter astonishment. Then I, too, was on my feet, with Sar Than, and we were at the window beside him, staring forth in turn.
* * *
My first impression was of vast space, a colossal reach of space that stretched far away before us, and into which our ship was racing on. And then I saw, with sudden awe and wonder, that this vast space was not the unlimited, unbounded space we were accustomed to, but was limited, was bounded, bounded by a colossal sheet of flowing flame that hemmed it in all directions. Above and below and before and behind us stretched this mighty wall of flame, a gigantic shell of fire that enclosed within itself the vast space in which our cruiser raced, a space large enough to hold within it a dozen solar systems like my own. Stunned, we gazed out into that mighty flame-bounded space, and then I flung out a hand toward it in sudden comprehension.
"We're inside the nebula!" I cried. "It's hollow! This vast open space lies at its heart, and those currents carried us down into it!"
For I saw now that this was the explanation. Unsuspected by any in the Galaxy the mighty nebula was hollow, its gigantic globe of flaming gas holding at its heart this mighty empty space, a space mighty in extent to our eyes, but small compared to the thickness of the great shell of fire that enclosed it. And down through that fire, that vast ocean of flame, the currents of the nebula had brought us, from its outer surface, down into this great space at its heart of which none had ever dreamed, and into which we had been the first in all the Galaxy to penetrate.
While we gazed across it, stunned, our cruiser was racing on into this vast hollow, away from the wall of flame behind us from which we had just emerged. And now, as we flashed on, Sar Than cried out too and pointed ahead. There, standing out black against the encircling walls of fire in the distance, was a small round spot, a spot that was growing to a black globe as we hurtled on toward it, a globe that hung motionless at the center of this mighty space, here at the nebula's heart. We were racing straight into the great cavity toward it and now there came a low exclamation from Jor Dahat, beside me, as his eyes took in the great globe ahead.
"A planet!" he whispered. "A planet here-within the nebula!"
My own eyes were fixed upon it, and slowly I nodded, but made no other answer as we flashed on toward the object of our attention, the black sphere ahead. And now as we swept on we saw that it was a sphere of truly titanic dimensions, larger by far than any of the Galaxy's countless worlds, and that as it hung there, at the nebula's heart, it was slowly revolving, spinning, as fast or faster than the nebula itself. Black and mighty it hung there, while all around it, millions of miles from it, there flamed the nebula's encircling fires. On and on we raced toward it, and for all those minutes of flashing flight none of us spoke, and there was no sound in the pilot room but the throbbing drone of the generators below. I think that we all felt instinctively that in the grim, colossal globe ahead lay the answer to what we had come to solve, and as we hurtled on toward it we watched it broadening before us in tense silence.
Larger and larger it was becoming, larger until its great black circle filled half the heavens before us. By then I had decreased our speed to a fraction of its former figure, and as we swept in toward the giant world I lessened it still further. Slowly, ever more slowly we moved, and now were circling above the great black planet, were beginning to drop cautiously down toward it. Eagerly we watched as the mighty world's surface changed from convex to concave, and as we dropped on we saw the needle of our atmosphere-pressure dial moving steadily forward, to show that this strange world had air, at least. Then all else was forgotten as our eyes took in the scene below.
I think that we had all half expected to see some evidence of life and civilization on this strange world, some building or group of buildings, at least. But there was none such. Beneath us lay only a smooth black plain, extending from horizon to horizon, devoid of hill or stream or valley, in so far as we could see, unnaturally smooth and level. And as we dropped nearer, ever nearer, the surprise we felt rapidly intensified, until when at last we hung motionless a hundred feet above the surface of this world exclamations of utter astonishment broke from us. For seen thus near, the surface of this mighty planet was as utterly smooth and level as it had seemed from high above, a black, gleaming plain without an inch-high elevation or depression, an inconceivably strange smooth expanse of black metal, that stretched evenly away in every direction to the horizon, smoothly covering this colossal world.
We looked at each other, a little helplessly, then down again toward the smooth and gleaming surface below. In that surface was no visible opening, no sign of joint or crack, even, nothing but the smooth blank metal. Then with sudden resolution I thrust forward the levers in my hands, sent our cruiser racing low across the surface of the giant, metal sheathed planet, while we gazed intently across that surface in search of any sign that might explain the enigma of its existence. On we sped, while beneath us flashed back the smooth metal plain, mile after endless mile. Then, gazing ahead, my eyes suddenly narrowed and I raised a pointing hand. For there, far ahead, I had glimpsed an opening in the gleaming surface, a round black opening that was resolving itself into a vast circular pit as our cruiser raced on toward it.
Nearer and nearer we flashed toward it, with Sar Than and Jor Dahat beside me gazing forward, their interest as tense as my own. And now we saw that the pit was of gigantic size, its circular mouth all of five miles in diameter, and that from its center there drove up toward the zenith a flickering beam of pale and ghostlike white light, so pale as hardly to be visible, a livid white ray that stabbed straight up toward the fires of the nebula far above. We were very near to the pale beam, now, flashing above the huge pit straight toward it. I had a glimpse of the great pit's perpendicular black metal walls, dropping down for miles into depths inconceivable, of something in those dusky depths that burned like a great white star of light, and then Jor Dahat suddenly uttered a choking cry, flinging an arm out toward the livid ray before us.
"That ray!" he cried. "It's not light-it's force! The nebula-stop the ship!"
At that cry my hand flew out to the levers, but a moment too late. For before I could throw them back, could slow or stay our progress, we had raced straight into the great pale beam. The next moment there came a terrific crash, as though we had collided with a solid wall; our ship rocked drunkenly in midair for a single instant, and then was whirling crazily downward into the depths of the mighty pit below us.