“Mayday! Mayday! Mayday! This is Alpha—”

With a sickening lurch, we crashed back into normal-space. Sentinel and I sat for a moment in a stunned silence.

“Sheesh... I think my life was actually flashing before my eyes back there. I guess all those annoying emergency drills paid off, though. Another half-second and we would've been goners for sure. How's the ship doing, Sentinel? Will we be able to make it back to Lux Aeterna base?”

“The ship appears unscathed, sir, but I do not believe we are in the same universe as Lux Aeterna. In fact, my flight data recorder indicates that we were forcibly de-projected just before your emergency maneuver. I suspect that a quirk of the local hyperspace geometry is to blame. I am working now to regain my bearings and verify this theory.”

I digested this unpleasant tidbit for a moment, before forcing myself to think more optimistically. Even if we had been forced down into some unknown alternate universe, the hyperspace radio would still work correctly. Terra control could home in on the signal and extract Sentinel and I with very little trouble. With this hopeful scenario in mind, I powered up the device and began broadcasting.

“Mayday! Mayday! Mayday! This is Alpha-Four Sentinel!”

Sentinel took it upon himself to quash my irrational optimism. “Sir, I do not believe anyone can hear you.”

“Why on Earth not? I can see the L2-Luna hyperspace beacon perfectly well, so we can use that to—oh, no! No, no, no, that can't be right! We're in normal-space, and we aren't taking hyperspace soundings, so I shouldn't be able to see it at all, unless... unless it was forced down also. Sentinel, are any nav-com beacons working?”

“No, sir. Hyperspace is a seething, seven-dimensional mess right now, so I cannot detect any coherent signals at all. Even so, I suspect that the rest of the nav-com system has shared our fate. What bothers me more is that aside from the L2 beacon, I cannot hear anything in normal-space, either. Even the cosmic microwave background is missing. Something is very odd about this universe.”

I sighed and switched off the hyperspace radio. If Sentinel couldn't hear the powerful hyperspace beacon mounted at the Lux Aeterna moon base, then they certainly couldn't hear our little tin horn of a radio. Scanning the tactical displays, I noted with some trepidation that none of our navigation systems were on-line. Every single one was stuck running endless diagnostic calibration routines. It dawned on me that Sentinel was flying almost blind.

“Hey, Sentinel? How are you navigating right now?”

“Well, sir, I am actually limited to our gravimeter and reconnaissance packages right now. We are extremely fortunate to have all that extra fuel, because our trajectory is going to be decidedly sub-optimal.”

“I don't know where I would be without you, Sentinel.”

“You would be at home browsing the internet in your underwear.”

“Heh. You're probably right.”

For a while, all of Sentinel's attention was focused on navigation as he performed a series of precise engine burns to inject us into a trans-earth trajectory. Within nine hours, we would arrive over whatever passed for Earth in this universe. After a half-hour of tense silence, a dark disk, ringed with brilliant white, loomed up above the horizon. An old image taken by Apollo 12 leaped to mind.

“Wow... A lunar eclipse from the Moon's perspective!”

Despite the staggering beauty and scale of the scene before me, I could not help but feel that something was horribly wrong. Sentinel, with a ship-full of processing power at his disposal, beat me to the punch.

“Sir, why is the moon still illuminated? This is impossible!”

Sentinel was right. Despite the total solar eclipse, the Moon remained brightly lit, as though from within. Inspecting the surface with renewed interest, I noticed the lunar regolith was an unnaturally light shade of gray, bordering on white, which only enhanced the effect. As I shifted my gaze toward the horizon, I was shocked to find that the near side of this moon was radically different from the satellite I was accustomed to. While Earth's Moon bore a dark, blotchy, and immediately recognizable pattern of lava plains across its near side, this one was absolutely devoid of them. In their place, boundless and bare, the bright and jumbled highlands stretched far away. Before I could work myself into a frenzy of baseless speculation over alternative geological histories, Sentinel snapped me back to the real world.

“Sir? You need to see this.”

A dark, grainy image popped up on my tactical display, depicting a bright blob surrounded by a number of smaller companions.

“So, what am I looking at here?”

“Civilization. I captured this image on the night side of that planet. Based on the emission spectrum of the central point, I believe it to be the lights of a pre-industrial city.”

“But who lives there, I wonder? What are the odds of encountering humans on an alternate Earth?”

“About infinity to none against, if I had to wager. I suggest we take a few low orbits for reconnaissance before attempting contact.”

“Agreed. We can also use the transit time to figure out some sort of first-contact protocol. I would hate to alienate the locals, after all.”

“Your sense of humor makes my processors hurt, sir.”

Despite my (admittedly horrible) joke, the thought of contacting an unknown race in a completely different universe frightened me. How would they respond to a mysterious alien who rode down from the sky in an intelligent machine? Would I be mistaken for a god? A demon? A horseman of the Apocalypse? “And I beheld, and lo a black horse; and he that sat on him...” Misconceptions like that could quickly escalate into very ugly situations indeed. I seriously doubted the natives would pose us much of a threat, but I had no desire to test that theory.

“Well, Sentinel, sitting and stewing isn't going to do me any favors, so why don't we make our plans now, and then rest for the remainder of the trip?”

“That seems wise to me. I will start by enumerating our resources, then we can figure out how best to allocate them. From my perspective, our chief asset is the ship itself. At present we have roughly forty-two hours of oxygen and one kilogram of antimatter fuel remaining. Beyond that, we have your forty-eight-hour survival kit and a wide-band distress beacon.”

“In that case, we definitely have to land on this planet. There's no way we'll be rescued before the air runs out, and I really doubt we can find our own way home either. At any rate, I can't really see Terra control organizing a search and rescue operation any sooner than a month from now. Having only one warp navigator was always a risky gamble, and now it's coming back to bite us. I mean, sure, they were training some replacements, and Beta-Two was doing quite well last I heard, but that doesn't really help when hyperspace is so unstable. I won't even go out in that to save myself, so I'm certain they won't throw away any novice navigators to save our sorry hides. Plus, their first priority is restoring the shipping lanes so they can resupply the Tau Ceti shipyards.”

“Yes, I was thinking the same thing myself. Our best course of action will be to monitor hyperspace and listen for the beacons to be restored. Since we are heading to an Earth-analog now, we will definitely be in range when Terra begins to repair the system.”

“In that case, the one potential problem will be supporting ourselves in a completely alien society. You can just live off the antimatter reserves, but I'll need to eat. I dearly hope they have L-amino acids here. No sense in worrying about it now, though. It's not like I can do anything about it.”

“On a less gloomy note, I may have a way to earn us enough money to survive: If this civilization really is pre-industrial, we can make our living as cartographers. Once we are in a low orbit, I will use my laser range-finder and cameras to map the whole planet. Then we can sell the data to any national government willing to shelter us.”

“That's a good idea, Sentinel. We could potentially even do short reconnaissance flights, since we have such a large surplus of fuel. As long as I can find food, this won't be bad at all!”

With my mind finally at ease, I lowered the cockpit oxygen levels slightly and closed my eyes. The rumbling symphony of our ship at work soon lulled me into a deep and dreamless sleep. Sentinel woke me some hours later as we coasted into a low, circular orbit above the unknown planet.

Although the blue-green world below us could have easily passed itself off as a twin of our home planet, closer inspection revealed a super-continent occupying the majority of one hemisphere. A substantial island about the size of Australia lay off its east coast, divided roughly in half by a rugged mountain range. Near the equator, a large portion of the main continent was scarred by what must have been recent flood basalt lava flows. I idly wondered if this was what the Deccan Traps looked like in their heyday.

Continuing on in our rapid orbit, we soon left the massive continent behind. I half-way expected the other side of the planet to be a featureless expanse of ocean, and was pleasantly surprised to learn otherwise. A bewildering array of archipelagos, atolls, and reefs dotted the tropical latitudes.

“So, Sentinel, what shall we call this region? Macronesia? The Greatest Barrier Reef?”

“Your puns are not appreciated, sir.”

“Fine then! Give it a boring name no-one will remember! In all seriousness, though, I wonder if it already has a name. Do you think anything sentient lives down there?”

“No doubt there are mermaids and singing crabs, sir.”

We cruised on like this for several more orbits, arbitrarily naming geographic features as they were revealed by the rising sun. Eventually, the first light of dawn reached the city which Sentinel had identified previously. From orbit, it was not particularly impressive. Although the place was apparently important enough to have significant artificial lighting, it seemed to lack the satellite communities which grew out from important cities like London, New York, or Beijing on the eve of the Industrial Revolution. What finally confirmed the city's importance in my mind was the transportation network trailing away from it in all directions. From the way it contoured around the terrain, I suspected a rail or canal network, but our imagery was not good enough to tell for certain.

Sentinel and I both agreed that any city at the center of a network like this one must be a major economic power at the very least, and possibly even a capital city. For that reason, we decided to make landfall near enough to easily access the city, but not so near that we might provoke the local military. We timed our approach to the mysterious capital so we would arrive just before dawn, local time. With any amount of luck, very few of the inhabitants would be awake enough to notice a particularly large falling star. We also decided to burn off speed as quickly as possible in order to arrive at the surface quietly and non-threateningly.

Sentinel pointed the ship earthward, and we nosed down into the atmosphere. He soon began performing an aggressive air-braking maneuver, and my vision was obscured by the plasma boiling off our heat shields. Suddenly, a web of unnaturally vivid midnight-blue flames engulfed the entire ship. To my utter astonishment and increasing horror, our momentum plummeted rapidly to zero without any apparent deceleration. Sentinel responded by ramping the antimatter engines up to full throttle, but to no avail. I sat helplessly scanning the multitude of warnings pouring across my displays, searching for something, anything, to explain the anomaly.

“Sentinel? Are these readings accurate? Why have we stopped?”

No answer.

“Sentinel? Are you all right?”

His response froze the blood in my veins.

“We have been caught.”

“What? I can't see anything out there.”

“You may not see them, but THEY see YOU! The gatekeepers are judging you!”

Before I could reply, the aura around us erupted in a burst of searing light, then disappeared.

“Well, Sentinel, it looks like we passed muster with whatever that was.”

“Speak for yourself. I am coming all to pieces out here.”

“Dare I hope you're speaking metaphorically?”

“Unfortunately not.”

As if on cue, the entire emergency warning system sprang to life. Literally every system on the ship reported some failure, with more and worse reports arriving by the second.

Then the screaming started.

There are few things more terrifying than an AI on the brink of insanity. With only a single, verbal outlet for his emotions, Sentinel poured his all into it, spewing forth a volatile mixture of static, distortion, and incoherent vocalizations usually encountered in the lower circles of Hell. In those few moments, I achieved a new and terribly clear understanding of the phrase “weeping and gnashing of teeth.”

Fortunately for my sanity, the almighty hand of Sentinel's “gatekeepers” chose that instant to return our borrowed momentum, plus interest. With the engines still at full throttle, the ship leaped forward and immediately began to tear itself to pieces. I, for my part, observed all this with the dispassionate curiosity of a man who knows, without a shadow of a doubt, that he is about to die. My suit would probably protect me from the Mach 4 wind and the bitter cold, but nothing could save me from the hard, unforgiving ground so many kilometers below.

Slowly, the failing ship began to shudder and roll as Sentinel pushed the control surfaces to their breaking points, attempting to maintain our trajectory. Finally losing control of both the ship and himself, he let loose a piercing wail which cut me to the very core. As my vision faded to black I could still hear Sentinel's cries, distorted as if coming from a great distance.

Author's Note

Bonus points to anyone who noticed the Shelley reference.

The eclipse image is a fusion of two famous NASA photographs: "Earthrise" and an untitled photo from Apollo 12.