The Twentieth Descent

I checked the instrument panel once more as our lunar lander entered the final stage of its journey. The Moon filled the viewport, its cratered surface sharpening by the minute. This was my third trip to Selene Station, and the sight of that empty landscape should have put me at ease. Instead, an inexplicable tension had settled across my shoulders.

"Final approach sequence initiated," Eleanor announced from the pilot's seat, her voice calm and professional. Her dark auburn hair was secured in a practical plait, and her fingers moved across the controls with practised precision.

Thomas nodded from the command console. "Looking good. We're on schedule to dock with Selene in forty minutes."

I worked through the pre-docking checklist, a routine so familiar that I could have completed it in my sleep. Six months at Selene Station conducting atmospheric research, then home.

Standard procedure. Nothing we had not done before.

The communications system crackled into life, interrupting my thoughts.

"Lunar lander three, this is Harwell Control. Priority transmission."

Thomas frowned and reached for the communications switch.

"This is Commander Whitaker. Go ahead, Harwell Control."

"Divert to Shackleton Outpost immediately. Coolant contamination detected in Selene Station's primary habitat. Repeat, divert to Shackleton Outpost."

The three of us exchanged glances. My stomach tightened.

"Harwell Control, please confirm diversion to Shackleton," Thomas said, his voice steady despite the unexpected order.

"Confirmed, Commander. Selene is currently unsafe. Proceed to Shackleton for mission continuation."

When the transmission ended, Eleanor turned towards us.

"Shackleton? That auxiliary outpost was mothballed years ago."

"Four years ago," I said, bringing up the outpost schematics on my tablet. "It was only intended as a temporary facility during Selene's expansion."

Thomas kept his expression neutral, but I saw the concern in his eyes.

"We have our orders. Eleanor, calculate new approach vectors for Shackleton."

"Yes, sir," she replied, already adjusting our course.

I opened what little information we carried on the outpost.

"Shackleton was designed for a maximum crew of ten. Basic research facilities, minimal life-support redundancy. It was never intended for prolonged occupation."

"We'll make it work," Thomas said, in a tone that ended the discussion. "How long to the new landing site?"

Eleanor checked her calculations. "The diversion adds one hour and fifty minutes."

The remainder of our approach was tense and quiet. We concentrated on our duties, but I caught both Thomas and Eleanor glancing at the communications system, perhaps hoping for an instruction to return to the original flight plan. None came.

An hour and fifty minutes later, Eleanor guided the lander expertly onto the lunar surface, roughly 3 kilometres from Shackleton's main entrance. The touchdown was smooth, but as the grey regolith settled around us, I noticed something that made no sense.

"Thomas," I said, pointing through the viewport. "The outpost has lights on."

He leant forwards and squinted at the distant structure.

"That's impossible. Its power should have been shut down when it was mothballed."

There was no denying what we saw. Several of Shackleton's windows were illuminated, casting pale rectangles across the lunar surface.

"Running diagnostics," I said, checking my instruments. "The power signature indicates full operational capacity."

"Life support?" Thomas asked.

I nodded. "Active environmental systems."

"Could someone have reactivated it remotely to prepare for us?" Eleanor suggested, although she did not sound convinced.

Thomas shook his head. "Without telling us? No. Something isn't right."

We suited up in focused silence. The walk to the outpost would take about twenty minutes in our EVA suits. Before we left, Thomas reminded us of the protocol.

"Standard approach procedure. Daniel, you're on communications and environmental readings. Eleanor, stay with me. Keep your emergency oxygen ready in case we need it."

The airlock cycled, and we stepped onto the lunar surface. Walking in low gravity always felt strange, however many times I did it. Each bounding step sent small clouds of regolith rising and falling in perfect arcs.

As we approached Shackleton, its illuminated windows came into clearer view. Through my visor I could make out equipment inside and fleeting shapes moving behind the thick glass.

"The outpost should be powered down," Thomas repeated, his voice tight in my earpiece.

I checked my handheld scanner. "The readings still show full operation."

The main airlock stood on the outpost's east side. When we reached it, I half expected to find it sealed or inoperable. Instead, the exterior panel illuminated as we approached.

"It's detecting our presence," I said.

Thomas paused, then pressed his gloved hand to the access panel. The outer door slid open smoothly.

We entered the small chamber, and the door closed behind us. The airlock functioned perfectly, as though someone had maintained it. When the inner door opened, clean, breathable air awaited us.

"Atmosphere normal," I confirmed, checking my instruments. "Oxygen stable. No toxins detected."

Thomas nodded. "Helmets off, but keep your suits on until we've secured the area."

We removed them carefully. The air was breathable, just as my readings indicated, but stale, with a faint metallic taste. Low amber emergency strips lined the main corridor. Machinery hummed somewhere in the background: life support, air recyclers and water systems, all operating as though the outpost had never been abandoned.

"This doesn't make sense," Eleanor whispered. Her voice sounded unnaturally loud in the quiet corridor.

We moved deeper into the facility and entered the crew room. What we found stopped us in our tracks.

The room looked inhabited. Three enamel cups stood on the central table, each containing cold, tannin-stained tea. Ration pouches and biscuit packets had been arranged beside the galley heater, some opened and partly consumed. A tablet lay beside one of the cups.

"Someone has been living here," Eleanor murmured, picking up a cup to examine it.

I went to the main computer terminal and activated it. The system came online immediately, without asking for a password. As I scrolled through its log entries, my stomach tightened.

"The last entry is dated eighteen months ago," I said. "It only says, 'Day 131. No response from Harwell Control. Continuing observations of the anomaly.'"

"What anomaly?" Thomas asked, looking over my shoulder.

I shook my head. "It doesn't say. There's nothing after that."

Thomas turned slowly, surveying the room with narrowed eyes. His hand moved instinctively towards the empty suit-tool attachment point at his hip. Selene Expedition 27 was a scientific mission. We carried no firearms.

A soft thud sounded somewhere deeper in the outpost. Thomas raised one hand for silence.

We stood listening. After a moment, another noise followed, somewhere between a scrape and a shuffle.

"I heard movement down there," Thomas said quietly, pointing towards the corridor leading to the cabins and laboratories.

Eleanor's eyes widened. "Could someone still be here after all this time?"

I checked the life-support status on my tablet. "The system says it is supporting six occupants."

"Six?" Thomas raised his eyebrows. "That's impossible."

Another sound came from the corridor, closer this time. Definitely footsteps.

Thomas squared his shoulders and stepped towards it. "Stay behind me."

We moved together into the darkened corridor, guided by the amber emergency strips. The footsteps had stopped, but I could feel the presence of something now.

We were not alone in Shackleton Outpost.

I froze in the galley doorway, unable to believe what I was seeing. Three people sat at the table who could not possibly exist.

Ourselves.

Another Thomas, another Eleanor and another Daniel, all wearing faded expedition patches and looking every bit as shocked as we were. The other Daniel's face was thin, with dark hollows beneath his eyes. His hair had grown too long, and a patchy beard covered the face I kept clean-shaven.

He stared at me in a way that made my skin crawl.

"This is impossible," Thomas whispered beside me. His hand again went towards the empty attachment point at his hip, searching by instinct for a weapon that was not there. Scientific expeditions did not carry firearms.

The other Thomas, whose hair was greyer and whose eyes were surrounded by deep wrinkles, slowly raised both hands.

"We've been expecting you," he said. His voice was identical to our commander's, but rough, as though he had hardly spoken in months. "We hoped you wouldn't come."

Eleanor seized my arm so tightly that I felt her fingers through my suit. Her face drained of colour.

"How...?" she began, but could not form the rest of the question.

The other Eleanor wore her dark auburn hair loose and tangled. She looked at our Eleanor with tears in her eyes.

"I'm sorry," she said. "I'm so sorry you're here."

I stepped forwards. "Who are you? Some sort of reception team? Is this a psychological trial?"

The other Daniel gave a humourless laugh.

"That's exactly what I said. Word for word." He tapped his temple. "Still thinking like a scientist. That won't last."

Thomas moved in front of Eleanor and me.

"Identify yourselves. Now."

The other Thomas sighed and rose.

"We're the crew of Selene Expedition 27. Commander Thomas Whitaker, science officer Daniel Mercer and systems specialist Eleanor Price. We were diverted from Selene eighteen months ago because of coolant contamination in its primary habitat."

"That's us," Thomas said flatly. "Those are our names and our expedition designation."

"Yes," the other Thomas replied. "We're you, or you're us. Time behaves differently here."

The other Eleanor wiped her eyes and spoke through her tears.

"We were ordered to divert to Shackleton, just as you were. Our lander was destroyed after we arrived. We've been stranded here ever since."

My mind raced through possible explanations: hallucinations caused by oxygen deprivation, an elaborate deception, clones, twins, impostors. None withstood scrutiny.

I took out my tablet and opened the expedition database. If these people were who they claimed to be, there should have been a record. I searched for Selene Expedition 27 and found one immediately.

I felt sick as I read the report.

"According to this," I said, my voice sounding distant in my own ears, "Selene Expedition 27 was lost with all hands eighteen months ago after its lunar lander suffered a catastrophic failure at Shackleton Outpost. The crew were declared dead."

"That tracks," the other Daniel said, his eyes darting nervously around the galley.

"No one could have survived the reported failure."

He leant forwards and lowered his voice. "We're you from an earlier iteration. Time works differently here. You'll understand soon enough."

Thomas stepped back.

"We need to discuss this privately," he told Eleanor and me.

We withdrew to the corridor outside the galley and stood close together.

"They cannot be us," Eleanor whispered. "It isn't possible."

"Agreed," Thomas said. "But they know our mission details and our names, and they are physically identical to us, only older and more worn down."

I ran a hand through my short hair, struggling to think clearly.

"If Shackleton was mothballed four years ago, who has been maintaining it? Life support is functioning perfectly and the power is on."

"Apparently they have," Thomas said, glancing back towards the galley.

"But how? And why claim they're earlier versions of us? It makes no sense."

"We need to contact Harwell Control," I said. "Request immediate extraction. Once the contamination at Selene is cleared, we can relocate there."

Thomas nodded. "I'll try to re-establish communications. The signal has been intermittent since we landed. Terrain masking may be part of it, but these readings aren't normal."

"What if they're telling the truth?" Eleanor asked quietly. "What if time really is broken here?"

I wanted to dismiss the idea, but after what we had seen, I could not.

"Then we find out what is causing it and whether it can be stopped. First, we need more information."

We returned to the galley, keeping our distance from our counterparts. The other Thomas seemed to understand our caution and did not press us.

"You have questions," he said. "That's natural. Ask whatever you like."

"If you're earlier versions of us," Thomas began, "how can you be here now? Wouldn't that create a paradox?"

The other Daniel laughed again, the same hollow sound.

"Paradoxes are the least of our problems. The usual rules do not apply here."

"What happened to your lander?" I asked.

The other Thomas and Eleanor exchanged a glance that tightened my stomach.

"Its systems failed during our first scheduled sleep period," the other Thomas explained. "Less than twenty-four hours after we arrived. We heard the blast from inside the outpost."

"But our landing was perfect," Eleanor protested.

The other Eleanor looked away, unable to meet her eyes.

"So was mine," she whispered.

Over the next few hours, we questioned them about their time at Shackleton. Their answers were detailed but often cryptic, as though they were withholding something crucial. They described eighteen months of isolation, failed attempts at rescue and phenomena for which they had no explanation.

"Communications with Earth are unreliable," the other Thomas told us. "Sometimes messages get through and sometimes they don't. Sometimes they arrive before they were sent. Terrain and the old equipment account for some failures, but not that."

As night arrived, or what we called night within our artificial duty cycle, Thomas obtained a weak connection with Harwell Control. The transmission was heavy with static, but we heard enough to understand that the supposed contamination at Selene remained unresolved.

No one could extract us soon.

That night I tried to sleep in one of the cabins our counterparts had assigned to us, in a section of the outpost well away from theirs. My thoughts kept returning to the impossible meeting, searching for a rational explanation and finding none.

A tremendous detonation jolted me awake.

The entire outpost shuddered, and alarms blared through the corridors. I leapt from my bunk and ran into Thomas and Eleanor outside.

"What was that?" Eleanor asked, her voice taut with fear.

"It came from outside," Thomas said, already heading towards the EVA preparation room. "Suit up. Now."

We pulled on our pressure suits quickly and methodically, although my hands trembled as I secured my helmet. Within minutes we had cycled through the airlock and stepped onto the surface.

I stopped dead.

The lander's tanks ruptured in a silent flash. Brief propellant-fed combustion flickered around the wreck and died almost at once in the vacuum, leaving glowing fragments, twisted metal and plumes of venting vapour scattered across the regolith. Our only means of leaving Shackleton had destroyed itself less than twenty-four hours after our safe landing.

"That's impossible," Eleanor whispered over the radio. "I checked every system before we left it. Everything was nominal."

"It was perfect," a voice said behind us.

The other Thomas had suited up and followed us outside.

"Just as ours was, until it wasn't."

I turned towards him. Through his visor, I saw no surprise in his face, only resignation.

"It always happens," he said, gesturing towards the wreckage. "Now you're trapped as well."

The last brief flame reflected in his visor and vanished.

I looked back at what remained of our only route home and felt nauseated. We were stranded at Shackleton with older copies of ourselves and a mystery that defied every scientific principle I understood.

Our problem was far worse than a destroyed spacecraft. Something about this place did not obey physics, perhaps not even time. Now we were trapped, just as the earlier crew had been for eighteen months.

We returned to Shackleton in stunned silence. I checked my watch. Not even twenty-four hours had passed since our arrival, and already we had lost our only means of escape.

The following week dissolved into confusion and mounting dread. We adopted a nervous routine, sharing the outpost with our earlier selves whilst trying to preserve some semblance of normality. Thomas established rules to keep the two groups apart whenever possible, but Shackleton's confined spaces made complete separation impossible.

I sat at the small desk in my cabin and updated our expedition log on my tablet. Recording everything helped me remain focused whilst the rest of my world seemed to collapse.

Day seven at Shackleton Outpost, I typed. Destruction of the lander continues to correspond with the pattern described by the earlier crew.

I paused, still uneasy with the term earlier selves, though it was more accurate than calling them visitors from an ordinary past.

Supplies remain adequate. Water recycling operating at 97 per cent efficiency. Air quality nominal. No response to repeated emergency extraction requests.

I saved the entry and leant back. The cabin was spartan: a narrow bunk, the desk, a small storage locker and little else. The walls were standard grey composite, but someone had drawn tiny marks in one corner near the ceiling.

On closer inspection, I realised they were tally marks, one for every day across precisely eighteen months.

A knock at the door brought me back to the present.

"Come in."

The door slid open, and Earlier Daniel stood in the corridor. His hair protruded at odd angles, and his eyes had the restless look of someone who had not slept for days.

"I need to show you something," he said without preamble.

I hesitated. Of our three counterparts, Earlier Daniel made me the most uncomfortable. Looking at him was like seeing a ruined version of myself, a preview of what I might become if we remained at Shackleton.

"What is it?" I asked, staying in my chair.

"The equations. I've been working on the equations." He raised his tablet, its screen crowded with complex formulae and diagrams. "You need to understand what's happening to us."

I checked my watch. The weekly briefing for both crews was due to begin in fifteen minutes.

"Can it wait until after the meeting?"

"No." Earlier Daniel entered without invitation and closed the door. "They don't want to hear it. Earlier Thomas thinks I'm losing my mind, but I'm the only one who sees clearly."

I stood and maintained a careful distance between us.

"Sees what clearly?"

"It's a time loop." He tapped rapidly at his tablet and opened a diagram. "The outpost is sitting on some kind of anomaly. Look at these energy readings."

The screen showed a pulsing waveform, with spikes occurring at regular intervals.

"What am I looking at?"

"Quantum distortions. They're strongest near the centre of the outpost and weaken as you move away." He brought up another display. "When your lander was destroyed, as ours was, it completed the circuit."

"What circuit?"

"The loop needs energy to sustain itself. The failures provide it." He stared at me, eyes wide. "Don't you see? It feeds on us, on the patterns we create."

A second knock interrupted us. Thomas stood in the doorway, and his expression tightened when he saw Earlier Daniel.

"The meeting is starting early," he said. His tone made clear that it was not a request.

Earlier Daniel hugged the tablet to his chest. "I was only explaining-"

"You can explain it to everyone," Thomas cut in. "Let's go."

I followed them to the crew room, where both crews had assembled around the large table. Eleanor sat beside Earlier Eleanor, both women staring at their hands. Earlier Thomas stood at the head of the table, waiting for us.

"Now that we're all here," he began after we had taken our seats, "I think it is time we spoke more frankly about our situation."

Thomas leant forwards. "I've been wanting to ask you several questions."

Earlier Thomas nodded. "I know."

"The coolant contamination at Selene," Thomas said. "Was it real?"

A heavy silence settled over the room. Earlier Thomas exchanged a look with Earlier Eleanor before answering.

"No. There was no contamination. It was fabricated to divert you here, just as it diverted us eighteen months ago."

Eleanor looked up sharply.

"Then who sent the order? Who diverted us?"

Earlier Eleanor would not meet her eyes.

"We did. We will. It is part of the loop."

"That makes no sense," I said. "How could you send us a message before you even knew we existed?"

Earlier Daniel laughed. The sound lifted the hair on the back of my neck.

"Time doesn't behave normally here. Cause and effect become tangled."

"I don't believe you," Thomas said flatly. "Harwell Control confirmed the diversion."

I took out my tablet. "I can inspect the communications logs. Every transmission is archived with its source metadata."

No one tried to stop me. I opened the logs from the day of our arrival and found the diversion order.

"This cannot be right," I muttered, checking the source code again.

"What is it?" Thomas asked.

I looked up, my mouth dry.

"The diversion order originated at Shackleton, not the UK Space Operations Centre at Harwell. Someone in this outpost transmitted a signal that imitated Harwell Control and brought us here."

Earlier Thomas nodded slowly.

"The same happened to us. We found the source record after our lander was destroyed."

"But who sent it?" Eleanor demanded.

"We don't know," Earlier Eleanor said. "The loop continues whether or not we understand it."

The meeting continued for another hour as Earlier Thomas described what his crew had learnt during their eighteen months at Shackleton. They had attempted to leave repeatedly, but every effort ended in equipment failure or some inexplicable accident. They could communicate with Earth occasionally, although the temporal anomaly degraded and distorted the signal.

When the meeting ended, I needed to escape the stale interior air. With Thomas's permission, I put on my suit and went outside to examine the wreckage of our lander.

The Moon was utterly silent as I crossed to the debris field. Our lander lay buckled and torn apart, its components scattered over the grey regolith. About 45 metres beyond it stood older wreckage, the remains of the earlier crew's craft.

I moved carefully around both sites, taking photographs and measurements. The distribution of the debris caught my attention. I plotted the major fragments from both failures on my tablet, then overlaid the two maps.

The match was exact, far too precise to be coincidence.

Every fragment from our lander aligned perfectly with a fragment from the older wreck, as though they were the same object observed at different points in time.

I stood on the lunar surface, staring at the display. The thought made me dizzy. If Earlier Daniel was right about the loop, if we were genuinely trapped inside some temporal fracture...

Something moved at the edge of my vision.

A suited figure was heading towards the outpost entrance, moving awkwardly in what passed for haste in lunar gravity. I recognised Earlier Daniel from the markings on his suit.

When I returned to Shackleton thirty minutes later, an alarm was sounding throughout the corridors. I hurried through decontamination and found Thomas and Eleanor running towards the cabins.

"What's happening?" I called, hurrying after them.

"It's Earlier Daniel," Thomas shouted over his shoulder. "Something is wrong."

We reached the earlier crew's cabins and found Earlier Thomas attempting to override a locked door. Terrible screams came from inside. Earlier Daniel's voice was raw with terror.

The door slid open, and we rushed in.

Earlier Daniel was on his knees in a corner, clawing at the walls with his bare hands. Blood streaked the grey surface where his fingernails had split against the hard composite.

"We have to get out!" he screamed, apparently unaware of us. "We have to get out before it happens again!"

Thomas and Earlier Thomas forced him to the deck and held him as he struggled, his eyes wild and unseeing.

"Before what happens again?" I asked, helping to restrain him whilst Eleanor retrieved a sedative from the medical kit.

Earlier Daniel looked at me, his eyes enormous with fear.

"Before we become them," he whispered, his bloodied fingers clutching my suit. "Before we send the message. Before we complete the loop."

As the sedative took effect, his grip slackened. I looked towards the wall he had been clawing.

Among the bloody streaks, he had scratched two words into the surface.

19 times.

I turned to ask Earlier Thomas what they meant, but he was already watching me with an expression that silenced the question. He knew I would discover the answer eventually.

Two weeks passed at Shackleton. I could not stop thinking about the bloody words Earlier Daniel had carved into his wall. Whenever I questioned Earlier Thomas about them, he looked away and changed the subject.

I sat at my desk updating the day's log. My fingers hovered above the tablet as I struggled to describe the change in Earlier Daniel. Deteriorated sounded too clinical. Becoming worse did not capture the horror of watching his mind disintegrate in front of us.

He rarely slept now. He paced the corridors at every hour of our artificial day and night, his footsteps ringing through the outpost's metal decks. The sound had become a constant part of our existence, a ceaseless reminder that something was profoundly wrong.

When he was not pacing, he wrote. He covered every available surface with equations and diagrams. The walls near his cabin had filled with mathematical formulae, arrows linking apparently random variables, and the same phrases repeated over and over: BREAK THE SEQUENCE. TEMPORAL DIVERGENCE POINT. ANOMALY CONTAINMENT FAILURE.

His eyes had changed as well. When we first arrived, they had held fear and a faint hope that we might somehow help him. Now they darkened whenever he looked at me.

At meals, I caught him watching from across the table, his fork suspended halfway to his mouth. His expression held such hatred and envy that my skin crawled. I began eating in my cabin or arranging my meals to avoid him.

Thomas noticed, of course. He noticed everything.

"You cannot avoid him for ever," he said one morning as I left the crew room with my breakfast: rehydrated scrambled egg and a vegetarian breakfast patty. "We're confined here together."

I slowed and let him catch up.

"I'm not avoiding him. I'm giving him space."

"His fixation on you grows every day," Thomas said, lowering his voice. "Earlier Thomas says the pattern has appeared in inherited records. Earlier Daniel sees you as the variable that might alter the equation."

"What does that even mean?"

Thomas shook his head. "I don't know, but we need to be careful."

After our first week, we had established a regular communications schedule with Harwell Control. Messages took hours to pass through what Earlier Thomas called the interference, and the replies arrived fragmented and distorted. It was our only connection to Earth, where time appeared to remain normal, and our only hope of eventual rescue.

That afternoon, I accompanied Thomas to the communications room whilst he transmitted our daily report. As on every other day, he included an urgent request for emergency extraction.

The reply arrived eight hours later, the voice dropping out every few words.

"Coolant situation at Selene remains unresolved. Extraction not possible. Maintain position. Estimate two further weeks. Sending supplies."

Thomas switched off the receiver and leant back, rubbing his eyes.

"Do you believe them?" I asked.

"What do you mean?"

"The contamination. The two-week estimate. What if these messages are part of the anomaly as well? Part of the loop?"

Thomas stared at the blank screen.

"I've been wondering the same thing."

That evening I found Earlier Eleanor alone in the observation room. Unlike Earlier Daniel, she had become quieter during the past fortnight, retreating into herself. She sat with her knees drawn to her chest and gazed out at the stars.

"May I join you?" I asked.

She indicated the empty chair beside her. From close by, I could see the dark circles under her eyes and the way her jumpsuit hung loosely from her body. She was not eating enough.

"Do you ever wonder whether the stars are the same?" she asked without looking at me. "Whether we're seeing the same sky as everyone else, or whether even that is different here?"

"I hadn't considered it," I admitted.

She took a small notebook from her pocket and offered it to me.

"I found this yesterday. It's the journal I kept when we first arrived."

I accepted it carefully. Its cover was worn and its pages softened and bent by frequent handling.

"I stopped writing after three months," she said. "It seemed pointless to keep count. Time loses its meaning here."

I opened the notebook. Her handwriting covered page after page, neat at first, then increasingly hurried and untidy. Each entry began with a date, although some had been crossed out and rewritten as if she had lost track.

"You received messages from Harwell Control as well?" I asked. "Promises of extraction?"

She gave a small, sorrowful smile.

"Two more weeks. Always two more weeks."

"And the promised supplies?"

"They never came."

She turned fully towards me.

"Have you worked out what nineteen means?"

My chest tightened. "No."

"You will." She looked back at the stars. "Eleanor already suspects. I can see it in her face when she looks at me. She knows she is becoming me."

I wanted to deny it, to insist that our Eleanor was fine, but the words would not come. The truth was that she had grown quieter as well, watching her earlier self with increasing unease.

The next morning, I found a new addition among Earlier Daniel's equations. He had drawn a circle with nineteen tally marks around its edge. An arrow pointed towards two labels: DANIEL 18 and DANIEL 19. Beside them, he had scratched: LOOP INTEGRITY FAILING. SEQUENCE MUST BE BROKEN.

"What are you working on?" I asked, trying to sound casual.

He spun round, surprise widening his eyes before suspicion narrowed them.

"You're studying my work."

"I'm curious," I said, taking a step back. "Perhaps I can help."

"Help?" He gave a harsh laugh. "You're the problem. You and all the others."

"What others?"

"The eighteen before us."

His face changed, as though he had suddenly realised something.

"So you do know. You're pretending you don't."

He moved closer and lowered his voice.

"Which one sent you? Was it Daniel 17? Did he warn you about me?"

"No one sent me," I said, retreating. "I'm trying to understand what is happening here."

"Liar," he hissed. "You stole my research. You're using it to manipulate the loop."

I turned and walked away quickly, his accusations pursuing me down the corridor.

When I reached the crew room, Thomas and Earlier Thomas were sitting in tense silence over cups of tea.

"Earlier Daniel is getting worse," I said without preamble.

Thomas nodded. "Earlier Thomas was just telling me."

Earlier Thomas looked exhausted, with deeper lines around his eyes than he had possessed two weeks earlier.

"The pattern repeats," he said. "The scientist breaks first. Too analytical. Too conscious of the impossibility."

"Repeats?" I said. "How many times has this happened?"

Earlier Thomas met my eyes, then looked away.

"You saw the wall."

That evening all six of us ate together at the galley table. The silence was oppressive, broken only by cutlery scraping against plates. Eleanor sat beside Earlier Eleanor, and both women picked listlessly at their food.

Thomas and Earlier Thomas ate steadily, watching Earlier Daniel from the corners of their eyes. I kept my head down and concentrated on my meal, but I could feel Earlier Daniel staring at me.

When I finally looked up, his eyes were fixed on mine. He gripped his fork so tightly that his knuckles had whitened.

"Do you know what I realised today?" he said, his voice unnaturally loud in the quiet galley. "He's reading my notes."

He pointed the fork at me.

"Every night, whilst I'm asleep, he goes through my research."

"No one is reading your notes, Daniel," Earlier Thomas said firmly.

"I've seen him," Earlier Daniel insisted, his voice rising. "He's stealing my work to use against me."

"That isn't true," I said. "I haven't touched your research."

"Liar!"

Earlier Daniel launched himself across the table, thrusting the fork towards my face. I jerked backwards. My chair toppled and I fell with it. The fork missed my eye by centimetres and tore across my cheek.

Thomas and Earlier Thomas reacted at once, seizing Earlier Daniel and dragging him away. He fought them, shouting incoherently, his face contorted with rage.

Eleanor pressed a napkin against my bleeding cheek. Earlier Eleanor watched with a vacant expression, as if she had known precisely what would happen.

Later that night, after Earlier Daniel had been sedated and locked in his cabin, Thomas, Earlier Thomas, Eleanor, Earlier Eleanor and I met in the observation room.

"We must restrict contact between the crews," Thomas said firmly. "Especially between Daniel and Earlier Daniel."

Earlier Thomas nodded. "We expected this. That's why we tried to prepare you."

"Prepare us for what?" Eleanor demanded, fear sharpening her voice. "What are you not telling us?"

Earlier Thomas and Earlier Eleanor exchanged a look I could not interpret.

"We hoped this cycle might be different," Earlier Eleanor said quietly.

"What cycle?" I demanded. "What does nineteen mean?"

No one answered. The silence stretched until Thomas broke it with a weary sigh.

"Everyone should rest. We'll establish new protocols in the morning."

I could not sleep. The cut on my cheek throbbed, but the unanswered questions kept me awake.

At about 03:00, I abandoned the attempt and decided to inspect the parts of Shackleton we had not yet searched thoroughly. The lower level contained storage and maintenance rooms. Most were unlocked and held exactly what I expected: ration supplies, water-recycling equipment and spare components for life support.

At the end of the corridor, however, I found a door that rejected my access code. I entered Thomas's override, which he had given me for emergencies. The lock clicked, and the door opened onto a small room lined with storage lockers.

The air smelt stale, as if no one had entered for months, perhaps longer.

I opened the first locker and found a tablet beside a handwritten journal. The cover was labelled SELENE EXPEDITION 27 - COMMANDER THOMAS WHITAKER. The writing inside was Thomas's, but the dates were wrong.

According to the journal, it had been written eighteen months earlier, when our counterparts arrived. The adjacent locker held another, nearly identical set of records, but with slight differences in wording, events and reactions.

Then I found another set. And another.

The handwritten pages were often more complete than the tablets. Digital files had been corrupted, erased or altered, whilst ink on paper appeared to persist more reliably through whatever afflicted Shackleton.

By the time Eleanor found me, I was sitting on the deck surrounded by eighteen sets of expedition logs. Each described the same sequence with minor variations. Each ended abruptly.

"Daniel," she said, barely above a whisper. "What is all this?"

I looked up at her as the truth finally began to settle over me.

"We're not the second crew to arrive here," I said.

"We're the nineteenth."

Eleanor picked up one of the journals and leafed through pages describing events we had already experienced: the diversion to Shackleton, the discovery of our counterparts, the destruction of the lander.

"Look at the handwriting," I said. "They're all from different iterations of us."

"But how?"

"The anomaly Earlier Daniel keeps talking about. It isn't merely bending time. It's repeating it, over and over, with each cycle slightly different from the last."

Eleanor sat beside me, her face pale in the low amber light.

"And it always ends the same way?"

I pointed to the abrupt ending of each journal.

"Something happens. Something none of them survives to write about."

"Earlier Daniel knows," she said.

"That's why he's losing his mind. Earlier Thomas and Earlier Eleanor know as well. They've been trying to warn us without telling us outright."

We sat in silence, surrounded by evidence of eighteen failed attempts to escape whatever held us in its grip at Shackleton Outpost. Eighteen iterations of ourselves had lived and died there, trapped in an endless cycle.

"What do we do now?" Eleanor asked at last.

I had no answer. The cut on my cheek stung, but it was nothing beside the sickness inside me. We were not merely stranded on the Moon without a way home. We were trapped in time, following a path that other iterations of us had already walked.

Somewhere in the outpost, Earlier Daniel was already planning his next move, convinced that I was the enemy he had to eliminate to break the cycle. I had seen how much he hated me when he came at me with the fork. I knew it was only the beginning.

Finding eighteen old expedition logs destroyed any hope that we were the first crew to become trapped there. Eleanor and I stayed awake throughout our artificial night, reading every journal, noting how each cycle differed and searching for anything that might help us escape the loop. By the start of the next duty period, we had found nothing.

There were only eighteen versions of the same nightmare, each playing out with minor variations. When we showed Thomas what we had discovered, he seemed to age before my eyes.

"We need to tell the others," he said at last.

Earlier Thomas received the news with disturbing calm, as though he had always known it was coming. Earlier Eleanor merely nodded, her eyes blank. Earlier Daniel, however, unravelled completely. His paranoia hardened into full psychosis.

"You're all part of it!" he screamed during dinner that evening, hurling his tray against the wall. "Puppets in the game, every one of you!"

Over the following weeks, his episodes became more frequent, more violent and harder to contain. He tore his cabin apart, covered every available surface with increasingly wild equations, and accused everyone - me in particular - of sabotaging his attempts to break the loop.

One month after our arrival at Shackleton, I helped Thomas move a steel medical cabinet against the wall of the converted sick bay. We had spent the morning reinforcing the room, removing anything Earlier Daniel might use as a weapon and fitting an observation window in the door.

"That should hold," Thomas said, stepping back to inspect our work. "Pass me the Pozidriv driver."

I handed it to him and watched as he secured the cabinet to the deck mounting points. Turning the sick bay into a locked holding room felt like crossing a line from which we could never retreat. We were finally admitting that one of us was beyond our help.

"What triggered the last attack?" I asked.

Thomas tightened the final fixing before answering.

"He saw Eleanor making tally marks on her arm. Claimed she was signalling to the others about his progress."

The previous day's incident had been the worst yet. Earlier Daniel had lunged at Eleanor in the corridor, seized her by the throat and slammed her against the wall. He had screamed about conspiracies and signals whilst his fingers tightened around her neck. If Thomas and Earlier Thomas had not dragged him off her, he might have killed her.

"We need a sedation schedule," Thomas said, wiping sweat from his forehead. "Something that will keep him calm without rendering him completely unconscious."

"We tried continuous sedation in an earlier cycle," Earlier Thomas said from the doorway. "It only made him worse when we brought him round."

He stood watching us work. The intervening weeks had carved deeper lines into his face. He looked tired in a way that sleep could never remedy.

"We had to do the same thing," he said, nodding towards our modifications. "It always develops this way. The scientist breaks first, then the pilot, then..."

He fell silent.

"Then what?" I asked.

He shook his head.

"You'll see soon enough."

Through the window, I could see Earlier Daniel strapped to the bed. The sedative had worn off sufficiently for his eyes to open, but he was no longer struggling against the restraints. His lips moved constantly, muttering equations and theories no one else could hear.

"How long did you keep him like this?" Thomas asked.

Earlier Thomas looked at his crewmate.

"Until the end."

My stomach twisted. I turned away, unable to look at the man with my face who had lost his mind. I did not want to see what I might become.

I left Thomas and Earlier Thomas discussing sedation protocols and went to find Eleanor. She had not appeared for breakfast, and I was worried about her. Since the attack, she had withdrawn even further.

I found her in the observation room, sitting cross-legged on the floor beside the large window. Her dark auburn hair was secured in its usual practical plait. Her back was towards me, but the set of her shoulders told me that she knew I was there.

"Breakfast is ready, if you want some," I said, stopping a couple of metres behind her.

She did not turn.

"I'm not hungry."

I moved closer and sat beside her. Only then did I see what she was doing. With a blue permanent marker, she was drawing careful tally marks on her left forearm. There were thirty-one identical lines.

"Eleanor," I said cautiously, "what are those?"

She finished the final mark before answering.

"Days. One month at Shackleton."

The marks were neat and perfectly aligned, as though she had been counting them for far longer.

"Earlier Eleanor showed me her identical marks yesterday," she said, finally looking at me.

There was a remoteness in her eyes that unsettled me.

"I'm becoming her."

"No, you're not," I insisted. "You're still you."

She gave me a small, sad smile.

"That's what I would have said a month ago. But look."

She rolled up her right sleeve. More blue marks covered the skin beneath, but these were less precise, scattered across her forearm like frantic scratches.

"I don't remember making these. I found them this morning."

My chest tightened.

"Perhaps you did it in your sleep."

"Earlier Eleanor has them as well, in exactly the same pattern." She traced the chaotic marks with one finger. "She doesn't remember making them either."

I had no answer.

More and more evidence was appearing that proved we were imprisoned within the cycle, and every new discovery was worse than the last.

"Have you seen what Thomas has been doing?" she asked.

I shook my head.

"He spends hours in the quiet corner of the recreation room, reading the Bible and talking to Earlier Thomas about what it all means." She pulled her sleeve back down. "They think God is testing us."

I had noticed that Thomas disappeared during off-duty periods, but I had not known where he went. The recreation room contained a quiet corner with a small shelf of religious books, nothing elaborate enough to call a chapel. I had never known Thomas to care about religion before.

Later that day, I found him sitting at a small table with an old Bible open before him. Several passages had been highlighted in different colours, and the margins were filled with notes in a variety of handwriting.

"Mind if I join you?" I asked.

He looked up, almost embarrassed to have been caught.

"I was only reading."

I sat opposite him.

"Eleanor said you've been spending time here."

Thomas nodded, running a finger beneath a highlighted passage.

"Earlier Thomas showed me this. Look."

He turned the Bible towards me. Revelation 20:7 had been highlighted in faded yellow. The verse described Satan being released from imprisonment after a thousand years.

"All these highlighted sections," Thomas continued, "concern eternal punishment, imprisonment and repeated suffering. This one was marked by the crew before Earlier Thomas's iteration."

He turned to another page.

"And this one by the crew before them."

Every passage concerned the same idea: people confined to unending suffering, forced to endure the same pain over and over. Different groups who had been there before us had found those verses, marked them and recorded their thoughts in the margins.

"What do you think it means?" I asked.

Thomas closed the Bible slowly.

"I think whatever has trapped us here is beyond our understanding. Earlier Thomas believes it's a test. I'm beginning to think he may be right."

I left Thomas to his thoughts and returned to what I understood: gathering data, looking for patterns and seeking physical explanations when spiritual ones offered me nothing.

Over the next few days, I examined every accessible part of Shackleton. What I found made no sense. Some sections appeared far older than others, bearing wear that should have taken decades to accumulate, rather than the four years since the outpost had supposedly been mothballed. Repairs to certain walls incorporated materials from entirely different eras: obsolete early-space-age alloys beside familiar modern composites and substances whose structures did not match anything yet manufactured on Earth.

The strangest sections contained technology I could not even identify. Circuits were formed from materials I had never encountered, arranged in designs more advanced than anything humanity possessed.

I was examining one of those sections when Earlier Thomas found me.

"Worked it out yet?" he asked, leaning against the corridor wall.

I shook my head.

"This shouldn't be possible. Some of this technology isn't ours."

"Not yet," Earlier Thomas corrected. He gestured for me to follow. "There's something you should see."

He led me to a maintenance room we seldom used. Several deck panels had been lifted, exposing the outpost's foundations. In the centre, embedded in the foundation material, was a faceted object roughly the size of a football. Its surface emitted a faint green-white pulse.

"What is that?" I asked, kneeling for a closer look.

"We don't know exactly," Earlier Thomas said. "But we have a theory. Shackleton exists at several points in time simultaneously. Whatever happened here trapped pieces of reality together, one on top of another, like geological strata."

He indicated the object.

"We think it began with this. The original construction team was drilling a thermal bore twenty-four metres beneath the outpost when they uncovered it and brought it up. Something that should never have been disturbed. Isotope analysis of the object and tests on the surrounding strata produced no meaningful age."

As I moved nearer, the green-white light brightened and its rhythm accelerated.

"It responds to proximity," Earlier Thomas explained. "It produces energy readings that fit no scientific model we understand. Crews have tried moving it, cutting it free, destroying it and removing the foundation around it. Nothing works. It cannot be shifted or damaged."

I leant back, trying to absorb what he had told me.

"So this thing, whatever it is, created the time loop?"

"Or it's a physical manifestation of the loop itself." Earlier Thomas shrugged. "Your guess is as good as mine. Earlier Daniel had theories about quantum entanglement and the object existing in several dimensions at once, but..."

"But he went mad before he could solve it," I finished.

Earlier Thomas nodded grimly.

"Like every iteration of him before."

I stared at the pulsing object, struggling to accept its existence.

"If we're the nineteenth crew to experience this, where are the others? Why do we encounter only one complete earlier crew at a time?"

"The loop recycles," Earlier Thomas said quietly. "When a cycle ends, it begins again with variations. The previous iterations are absorbed somehow, except for one crew that remains to serve as witnesses for the next."

"And this time, that's you."

"Yes."

"What happens to you when the cycle resets?"

His expression darkened.

"I don't know. None of us does. Perhaps we cease to exist. Perhaps we become part of the next cycle in some way we cannot understand."

I thought of the eighteen sets of logs we had found, each ending abruptly.

"How does the cycle end?"

He turned away from the object, leaving his face in shadow.

"You already know too much. Knowledge only accelerates the progression."

"Earlier Daniel knew," I pressed. "That's why he broke."

"Yes."

Earlier Thomas walked towards the door.

"And now you know as well. Be careful what you do with that knowledge, Daniel."

After he left, I remained for a while, watching the object pulse with its impossible light. The idea that it existed outside ordinary time, creating a bubble in which past, present and perhaps future had merged, should have been absurd. Yet the evidence surrounded us: the earlier crew, the technology from incompatible eras and the outpost itself, worn and repaired across spans of time it could not possibly have endured.

When I returned to the main level, I found Eleanor still in the observation room. She had not moved for hours. She was staring out across the lunar surface.

"Did you know," she said without looking at me, "that I sometimes see movement out there? Shadows that shouldn't exist."

I sat beside her.

"What sort of shadows?"

"People in pressure suits."

She pressed her palm to the thick glass.

"I think they're the others. The ones who came before."

The thought chilled me.

"Have you told Thomas?"

She nodded.

"He says Earlier Thomas sees them too. He thinks they're ripples in time."

At last, she turned towards me.

"What did you find today? I can tell you found something."

I told her about the object beneath the deck and Earlier Thomas's theory of overlapping realities.

"Do you think we can break it?" she asked when I had finished.

"The cycle? I don't know. Eighteen crews before us have tried and failed."

She looked back towards the lunar landscape.

"Perhaps we're different. Perhaps we can do something they couldn't."

I wanted to believe her. Then, as I watched the empty ground beyond the window, I saw what she had described: a shadow moving where none should have been, the wavering outline of a pressure suit that lasted for a second before vanishing.

They were temporal after-images, not additional living occupants. Even knowing that did nothing to lessen the horror.

I finally understood why Earlier Daniel had lost his mind. The truth was too much for anyone to bear. We were trapped in a time loop with fragments of earlier and future selves, circling an alien artefact that defied comprehension. Somewhere in the outpost, confined in our improvised cell, Earlier Daniel repeated his equations without end.

I wondered how long it would be before I became him.

Six weeks into our imprisonment at Shackleton Outpost, an alarm shrieked through the corridors.

I jerked awake and dragged on my boots. Red emergency lights flashed in time with the siren, washing the grey composite walls in crimson. I seized the improvised battery-powered restraint baton we had assembled from spare parts. We needed it because Earlier Daniel was becoming increasingly violent.

The alarm could mean only one thing: he had escaped.

The corridor outside my cabin was empty. I ran towards the sick bay, gripping the baton in front of me. We had been taking turns administering Earlier Daniel's medication, giving him enough sedative to keep him calm without leaving him completely unconscious. That day had been Earlier Thomas's turn.

I rounded the corner and stopped. Earlier Thomas lay face down on the metal deck, blood seeping from the back of his head. I knelt beside him and checked his pulse.

He was alive, but unconscious.

"Thomas!" I shouted, hoping our commander was nearby.

There was no answer.

The sick-bay door stood open, its lock smashed apart. Inside, the restraints on the bed were empty. The medical cabinet had been forced open and its contents strewn across the deck: broken vials, crushed packaging and shattered syringes.

Earlier Daniel had left a trail behind him - dented wall panels, overturned equipment and smears of blood from injuries sustained during his escape. I followed it cautiously, holding the baton ready. It led towards the communications room.

"Daniel?"

Eleanor's voice came through my personal communicator.

"What's happening?"

"Earlier Daniel has escaped," I whispered. "He attacked Earlier Thomas. I'm tracking him towards communications. Where are you?"

"In the observation room with Earlier Eleanor. Commander Whitaker is on his way from the galley."

"Stay there. Keep Earlier Eleanor with you."

The communications-room door had been jammed shut. Through its narrow window, I could see Earlier Daniel inside with his back to me, hunched over the primary console. His hands darted across the controls, throwing switches and turning dials. His jumpsuit was torn and bloodstained, and his hair hung in matted clumps.

I entered my access code. Nothing happened. He had overridden the system.

"Earlier Daniel," I called through the door. "Open it. We can talk about this."

He turned. I stepped back when I saw his face. His pupils were so dilated that his eyes appeared almost black, with only a thin ring of colour around them. Blood from cuts sustained during his escape was smeared across his cheeks and forehead. His dry, split lips were drawn into an expression that was neither smile nor snarl.

"I'm saving us all," he said hoarsely. "I've finally worked it out."

Behind him, the communications equipment flashed as it transmitted messages that the anomaly would distort or prevent from reaching Earth. I heard running footsteps and turned to see Thomas approaching with a metal bar in his hands. The scientific expedition carried no firearms, and his free hand moved instinctively towards the empty suit-tool attachment point at his hip before he seemed to remember that fact.

"He's barricaded himself in," I said quickly. "He's trying to transmit to Earth."

Thomas nodded, his expression grave.

"We need to get inside before he destroys our only link to Harwell Control." He studied the door. "The manual release may still work. Cover me."

He went to a small panel beside the door and prised it open with the Pozidriv driver from his pocket. Inside was the mechanical backup, designed to operate even after a total systems failure.

Thomas pulled the release lever. The door hissed as its lock disengaged.

Earlier Daniel heard it. He snatched up a metal pipe that had once formed part of the room's ventilation assembly. As the door opened, he stood poised to strike, tense and defensive.

"Stay back," Thomas warned me. "I'll go first."

I pushed past him. This was my counterpart. My responsibility.

"Earlier Daniel, put down the pipe. Whatever you're trying to do -"

"I know how to break the loop!" he shouted, his gaze wild and unfocused. "One of us has to die."

He sprang at me with terrifying speed and swung the pipe at my head. I ducked, feeling the air move as it passed centimetres above me. Thomas tried to seize him from behind, but Earlier Daniel twisted free with unnatural agility and drove the pipe into his ribs. Thomas stumbled backwards, gasping.

Earlier Daniel turned to me.

"You," he wheezed. "It has to be you."

He swung again. This time the pipe struck my shoulder. Pain burst down my arm, but I remained on my feet. We circled one another in the confined room, knocking equipment aside as we moved. A monitor crashed to the deck and its screen shattered.

The communications console sparked when Earlier Daniel backed into it and tore several connections loose.

"The loop needs a different kind of energy to break," he said. His voice was eerily calm, despite the frenzy of his movements. "Death energy. But not just any death. The right one."

He lunged, and we grappled amid the wrecked equipment. He was far stronger than his wasted frame suggested. His derangement seemed to have stripped away every instinct for self-preservation, giving him a strength I could not match.

"Why me?" I gasped as we struggled. "Why not you?"

His face came close to mine, near enough for me to smell sour medication on his breath.

"Because you're the mistake," he hissed. "You're the variable that shouldn't exist."

He slammed me against the wall and crushed the pipe across my throat. I choked and tried to force him away, but his weight and the pressure against my windpipe were too much. Black spots crept into the edges of my vision.

My hand swept blindly along the wall, brushing broken equipment, loose wires and then something sharp: a shard from the shattered monitor. I closed my fingers around it and felt it cut into my palm.

Earlier Daniel pressed harder, his face contorted.

"It should be you," he wheezed.

With the last of my strength, I drove the shard into his neck.

His eyes widened. The pressure vanished from my throat as he staggered backwards, both hands clutching the fragment lodged in his flesh. Blood surged between his fingers, bright and appallingly fast. He tried to speak but produced only a wet gurgle.

Earlier Daniel fell to his knees and pitched face first onto the deck. Blood spread beneath him. His body convulsed once, then became still.

I slid down the wall until I was sitting, unable to look away from my own dead face.

I had killed myself - not an ordinary version from my past, but an earlier iteration of me created by the loop. The act felt profoundly wrong, an impossibility made flesh. I turned aside and vomited.

Thomas knelt beside Earlier Daniel and checked for a pulse. His face was pale.

"You had no choice," he said quietly. "He would have killed you."

I wiped my mouth with the back of my hand.

"What do we do now?"

"We tell the others, and..."

He looked down at the body.

"We deal with this."

Laying Earlier Daniel to rest was a strange, grim business. We wrapped his body in a sheet from the sick bay and carried it outside in our pressure suits. We had no excavation tools capable of cutting through the compacted regolith, so a short distance from the main airlock on the outpost's east side, we scraped together a shallow covering of loose regolith and weighted it with stones.

No one spoke as we worked. What could any of us have said?

Earlier Thomas had regained consciousness but remained in the sick bay with a concussion. Earlier Eleanor stood apart during our makeshift funeral, her expression vacant and remote. Eleanor stayed near her, touching her arm occasionally as though she needed reassurance that her earlier self remained real.

As we placed the last stone over the sheet, Eleanor gasped.

"Look."

Where white fabric should have shown between the stones, something impossible was happening. The sheet was becoming translucent. Beneath it, Earlier Daniel's body was fading as well, until we could see the lunar surface through him.

"What's happening?" I asked. My voice sounded strange through the suit communications system.

"The loop is reabsorbing him," Earlier Thomas replied over the radio. He had insisted on monitoring the burial from the sick bay. "When we die here, we don't remain dead. We become part of whatever comes next."

We watched in horror as Earlier Daniel's body disappeared completely. His clothing and the blood-soaked areas of the sheet faded with him, as though their physical entanglement with his body drew them into the same erasure. A few minutes later, the rest of the sheet vanished. The separate stones remained, resting over an empty patch of regolith.

It was as though he had never existed.

Back inside the outpost, I stood beneath the shower for nearly an hour, trying to wash away the sensation of Earlier Daniel's blood on my hands. I could not stop thinking about killing him.

During the next artificial night, I could not sleep. Whenever I closed my eyes, I saw his face as he died. In him, I saw myself dying.

I rose and walked through the quiet corridors, eventually stopping outside his former cabin. It had been locked since his first violent outburst, when we moved him to the sick bay.

Without thinking too closely about it, I entered Thomas's override code. The door slid open.

The walls inside were covered with equations, diagrams and fragments of writing. Some had been scrawled directly onto the panels; others filled sheets of paper fixed up in overlapping layers. The bed stood against one wall, its covers in disarray. On the desk lay a leather-bound journal that I recognised as Earlier Daniel's logbook.

I picked it up and hesitated before opening it. It felt like an invasion, even if I was technically reading my own work. Yet Earlier Daniel was gone, and handwritten records had already proved more durable across the cycles than digital files corrupted by the anomaly. His journal might contain information that could help us escape.

The early entries were ordinary enough: daily reports, observations and theories about the outpost and the object beneath it. As I read on, the handwriting deteriorated and the theories became increasingly unhinged.

Whole pages contained a single phrase, written again and again.

Break the loop.

Break the loop.

Near the end, I found what I had been seeking - and what I had dreaded finding.

There were detailed plans for killing his later self. Me. He had drawn diagrams of the communications room and made notes about when I might be alone and vulnerable. He had listed possible weapons, methods and opportunities.

The final page contained a single paragraph in surprisingly neat handwriting.

If you are reading this, I failed and you killed me instead. That is acceptable.

Death is the key. I am almost certain now. The loop requires death to reset, but it also requires the correct kind of death. Not suicide. Not accident. Blood sacrifice, willing or unwilling. If I am right, my death will alter the pattern. Watch for it. Be ready.

I closed the journal. My hands were trembling.

Earlier Daniel had not attacked me in a blind frenzy. He had deliberately engineered what he believed to be the death required to break the cycle. I had given him precisely what he wanted.

I returned to my cabin and remained awake for the rest of the artificial night, wondering how his death might have changed the loop and what it meant for those of us still trapped at Shackleton.

Two months after our arrival, I woke to Eleanor's screams.

The sound tore me from dreamless sleep, raw and primal enough to bypass thought and drive me straight into motion. I flung aside my blanket and ran barefoot through the cold metal corridors, following her cries to the shared washroom.

Eleanor stood in the doorway with both hands pressed over her mouth, her body rigid with shock. Inside, water from the shower mingled with dark red trails that spiralled towards the drain.

Earlier Eleanor lay crumpled on the tiled floor, her skin deathly pale against the blood pooling around her wrists. A sharp fragment of mirror gleamed beneath the washroom lights, its edge stained red.

Thomas arrived seconds after me and pushed past us both. He crouched beside Earlier Eleanor and searched for a pulse he would not find. Water continued to fall, splashing across his shoulder as he leant into the shower enclosure.

"Turn it off," he said quietly.

I reached inside and closed the valve. The sudden silence made everything worse. Now we could hear Eleanor's ragged breathing behind us.

"She told me yesterday that she couldn't do it any longer," Eleanor whispered. "She was watching the loop continue. She knew what came next."

I turned to her. She stood frozen, staring at her own dead body, one hand rubbing unconsciously at her wrist. Her fingers circled the precise place where Earlier Eleanor had opened her veins.

Thomas rose, water dripping from his clothes.

"We need to move her."

"Where?" I asked.

The question felt foolish as soon as I spoke. Shackleton had no mortuary and nowhere suitable to keep a body.

"The same place as before," Thomas said.

We wrapped Earlier Eleanor in the shower curtain, trying not to look at her face or the terrible wounds on her wrists. As we carried her along the corridors towards the airlock, I kept glancing at Eleanor, who walked several paces behind us. She could not take her eyes from the bundle in our arms.

Outside, we laid Earlier Eleanor beside the shallow mound where we had placed Earlier Daniel two weeks before. It looked smaller now, and some of the stones had shifted after his body disappeared.

We stood in a semicircle around the wrapped body, our breath misting the inside of our helmet visors. No one spoke. There was nothing left to say that had not already been said when Earlier Daniel died.

Through the clear shower curtain, I saw the change begin. Earlier Eleanor's outline blurred and became translucent. Within minutes, the grey regolith was visible through her chest and face. Her clothes and the blood clinging to her body faded with her until only the outer portions of the bloodstained curtain and the separate mirror fragment remained.

Then the curtain disappeared too. The shard stayed where it had been placed, a distinct inorganic object untouched by the body's erasure.

Back inside Shackleton, Eleanor went directly to her cabin without speaking. Thomas and I cleaned the washroom in silence, washing away the blood until no trace remained, just as Earlier Eleanor's body had vanished from the surface.

"Do you think that will happen to all of us?" I asked as I wrung out the mop.

Thomas looked up from the shower drain.

"I think it happens to anyone who dies within the loop. They're recycled."

"That's what Earlier Daniel was trying to say about death feeding the cycle."

Thomas nodded slowly.

"He may have understood part of it. Earlier Thomas has theories as well."

"You've been speaking to him often."

"He understands this place better than any of us."

Thomas stood, wincing at the stiffness in his knees.

"I'm worried about Eleanor."

"So am I."

We finished cleaning without another word. The washroom looked normal again, with no sign of what had happened there only hours earlier. Even the broken mirror had been replaced; Thomas found a spare in storage.

Neither of us mentioned the missing piece Earlier Eleanor had used to kill herself. Unlike her body and the material touching it, the separate shard had remained outside.

Over the next few days, Eleanor scarcely spoke. She spent most of her time in the observation room, gazing at Earth through the broad window or writing in a journal she would not allow anyone to read. When she did interact with us, her behaviour became increasingly strange.

At dinner, four days after Earlier Eleanor's death, I placed a bowl of reconstituted soup before her.

"Here you are, Eleanor."

She did not respond. She only stared at the table.

"Eleanor?" I repeated.

"Earlier Eleanor?" Thomas tried gently.

She looked up at once.

"Yes?"

A cold sensation passed through me.

Eleanor blinked, confusion spreading across her face as she realised what she had done.

"I... I'm sorry," she stammered. "I don't know why I..."

Thomas reached across the table and squeezed her hand.

"It's all right. We're all struggling."

But it was not all right. Something was happening to Eleanor that went beyond grief or stress. She was losing her hold on her own identity, slipping into the role of the woman whose body we had watched dissolve into nothing.

That artificial night, unable to sleep, I went in search of Thomas. Shackleton felt different with only five of us left: emptier, quieter and somehow larger. I checked the operations room and laboratories before heading towards the quiet corner of the recreation room.

I found Thomas sitting with Earlier Thomas. Both men looked up as I entered, their identical faces marked by exhaustion. A Bible lay open between them on the small table, its pages bristling with coloured tabs.

"Daniel," Thomas said with a nod. "Couldn't sleep?"

"Too much on my mind."

I sat opposite them.

"What are you doing?"

Earlier Thomas closed the Bible carefully.

"Comparing notes."

He looked worse than Thomas: thinner, with deeper shadows beneath his eyes and more grey in his beard. Whatever was happening at Shackleton seemed to accelerate the toll it took on people.

"I've been documenting every variation of the loop," Earlier Thomas explained, pushing a thick notebook towards me. "Different configurations, different outcomes. I'm looking for patterns."

I opened it. Page after page was filled with notes, diagrams and timelines. Earlier Thomas had devised a meticulous system for tracking events across multiple cycles, combining the inherited handwritten records with fragments of memory that bled between iterations. He could not have lived normally through all nineteen himself, but some recollections appeared to survive the reset, and paper endured more reliably than digital storage.

"You think this is a test?" I asked, remembering what Thomas had told me about his counterpart's religious interpretation.

Earlier Thomas nodded slowly.

"God, aliens, some cosmic intelligence. Something is testing us. It forces us through the same events with minor changes and watches how we respond."

"And you've recorded all of it?"

"As much as I remember, and as much as the earlier crews left behind."

He took back the notebook and opened it at a particular page.

"There is only one constant across every loop preserved in the records or recovered through memory bleed."

"What is it?" I asked.

"When one iteration of each of us dies, the countdown begins."

Thomas leant forwards.

"What countdown?"

Earlier Thomas looked from him to me, his expression grave.

"The countdown to the reset. Once the earlier crew is gone, the current crew follows. Then the loop begins again. That is why Earlier Eleanor couldn't endure it any longer."

"She knew what was coming," Thomas said quietly.

Earlier Thomas nodded.

"She always breaks second. The scientist first, then the pilot, then..."

He stopped and looked at Thomas.

"The commander," Thomas finished.

I tried to make sense of it.

"So after Earlier Daniel died, Earlier Eleanor knew she would be next? Is that why she killed herself?"

"Yes and no," Earlier Thomas said. "She knew it would happen, but not how. Sometimes she becomes ill. Sometimes there is an accident. This time..."

He closed his eyes briefly.

"This time she chose her own way out."

I thought of the mirror fragment and the precise wounds across her wrists. She had made it as quick as she could.

Earlier Thomas sighed.

"Now it's my turn."

The flat certainty in his voice frightened me.

"What do you mean?"

"The pattern continues. Three deaths, each with its variation."

He looked directly at Thomas.

"You know what I'm asking."

Thomas met my gaze for a long moment, then gave his earlier self a slight nod.

I left them to their quiet conversation, disturbed by what I had heard but unsure how to intervene. The notion of a countdown triggered by the deaths of our earlier counterparts kept me awake when I returned to my cabin.

At about 02:00, I heard movement in the corridor. Soft footsteps passed my door, then returned ten minutes later. I waited until they had receded before getting up to investigate.

The outpost was dark, illuminated only by the low amber emergency strips along the deck. I followed the route of the footsteps towards the cabins where the remaining earlier crew had slept.

As I approached Earlier Thomas's cabin, the door opened and Thomas stepped out. He stopped dead when he saw me. Two pre-filled morphine syringes from the outpost's controlled medical stores were in his hand. Tears covered his face.

"I gave him peace," Thomas said before I could ask. "He asked me to. He said he'd done it before for others."

I pushed past him into the cabin.

Earlier Thomas lay on the bed with his eyes closed and his hands folded over his chest. If not for the empty syringe on the bedside table, I might have believed he was asleep. In death, his face was calm, every familiar line of anxiety smoothed away.

"Morphine?" I asked.

Thomas nodded. Enough to stop his heart. Quick and painless. I should have felt horror, anger, something.

Instead, all I felt was a dull acceptance. The loop had claimed another of its players, right on schedule.

"He was in pain," Thomas said quietly. "He had been since the last cycle. Something happened to his back during their landing failure. Their version was worse than ours would have been."

Would have been, if Earlier Daniel had not warned us about the flaw in the landing sequence.

Thomas slipped the unused pre-filled morphine syringe into his pocket. "A small variation. Just enough to keep it interesting, I suppose."

We stood together and watched Earlier Thomas's body begin the process we had seen before. His hands and feet became translucent first, and then the change spread towards the centre of his body. Unlike the previous deaths, we could see everything clearly now that we were in his cabin, without spacesuits, curtains or sheets obscuring our view. It was deeply wrong to watch.

His face blurred, became transparent and then disappeared completely. The sheet and clothing faded where they remained entangled with him. The blanket beneath him slowly settled as his weight vanished.

The empty syringe remained on the bed, separate and solid. It was the only clear evidence that he had ever been there.

"Three down," Thomas said, staring at the empty bed. "Now the hard part begins."

"What do you mean?"

He turned towards me. In the low amber light, I could not read his expression.

"We're alone now. Just the three of us. No more guides. No more warnings."

"Perhaps that's better," I said. "Perhaps we can break the pattern without them."

"Or perhaps we're exactly where the loop wants us to be." Thomas headed for the door. "Get some sleep, Daniel. Tomorrow we begin phase two."

"Phase two of what?"

He paused in the doorway.

"Of whatever is testing us. The real experiment couldn't begin until they were gone."

He left me alone in the cabin where Earlier Thomas had disappeared. I sat on the edge of the empty bed and tried to make sense of everything that had happened: the deaths, the disappearances, the loop in which we appeared to be trapped.

Beyond the small window, Earth hung in the black sky, beautiful and impossibly distant.

Somewhere up there, people were living ordinary lives without the faintest idea of what was happening to us. They moved through time in one direction, forwards, never doubling back or repeating. I thought about Earlier Daniel, trying so desperately to break the cycle through his own death. I thought about Earlier Eleanor choosing to end her life rather than wait for whatever came next.

I thought about Earlier Thomas asking us to help him leave on his own terms.

All three of them were gone, but traces of their actions remained. Thomas, Eleanor and I were still there, alone in Shackleton Outpost with the alien thing that had trapped us. The countdown had begun, just as Earlier Thomas had warned.

But a countdown to what? Our deaths? Another reset? Something worse?

I returned to my cabin but did not sleep. I sat at the desk, writing down everything that had happened in the hope of finding some pattern, some clue the earlier iterations of ourselves had missed. Earlier Thomas's records suggested that handwriting persisted more reliably than digital data when one cycle bled into another, so I kept writing long after my hand began to ache.

The answer had to be there somewhere. It had to be. I could not accept the alternative: that we were condemned to repeat the same events over and over, with minor variations but no possibility of escape.

Three months into our confinement at Shackleton Outpost, I sat alone in the operations room. It was too quiet. My tablet was nearly full of notes, measurements and theories, and I had filled several paper notebooks as well. I was still searching for a pattern or weakness we might exploit.

I examined weeks of temperature readings from the maintenance room containing the artefact. I sorted them by time, by our artificial duty cycle, by the phases of Earth as seen from Shackleton, and finally at random, hoping some relationship would emerge. After hours of staring, the figures merged into meaningless columns.

The outpost felt empty without the earlier crew. There was too much silence in places where there had once been at least some human movement. Now only the three of us remained in a metal habitat designed for ten, and we spent most of our time avoiding one another.

I closed the environmental program and opened Shackleton's original construction plans again. There had to be something in the designs that explained why the outpost had been built above whatever lay beneath it. Perhaps I had overlooked something during my countless previous examinations of the schematics.

My stomach growled, reminding me that I had missed breakfast. I could not remember whether I had eaten the previous evening either. The days had blurred together, distinguished only by my meticulous notes and the regular checks Thomas insisted we make according to the artificial duty cycle.

I walked to the galley, my footsteps echoing along the empty corridors. The lighting had begun to fail in several sections. Strips flickered or dimmed without warning, and none of us had found the energy to repair them.

Eleanor sat alone at the table with a cold enamel cup in front of her. A brown stain marked the level to which she had drunk the tea.

She did not look up when I entered. Her dark auburn hair had come loose from its practical plait and hung lank and unwashed around her face. She had lost so much weight that her flight suit sagged from her shoulders.

"Morning," I said, going to the food store.

She did not reply. I had stopped expecting her to. Over the previous few weeks, she had spoken less and less until our conversations consisted solely of whatever was necessary to keep the outpost functioning.

I heated a ration pouch of rehydrated scrambled egg and a vegetarian breakfast patty, then sat opposite her.

She stared at her reflection in the polished metal tabletop, one hand resting beside it.

"You should eat something," I said.

Eleanor's fingertips moved in slow circles across the metal. She seemed to be trying to touch her reflection, as if she thought her hand might pass through the surface. I had caught her doing it more frequently of late, examining reflective panels throughout the outpost as though each one might be a doorway.

"They're coming to collect us today," she said suddenly.

I stopped with my fork halfway to my mouth.

"Who is?"

"Harwell Control."

Her voice was flat and without emotion.

"The coolant contamination in Selene Station's primary habitat has been cleared. They're sending an extraction crew."

Anxiety tightened my chest. This was not the first time she had made such a claim. The previous week, she had insisted that a supply craft had landed outside. The week before that, she had packed her personal belongings because she was certain we were leaving.

"That's good news," I said carefully. "Did Thomas tell you?"

She did not answer. She continued tracing her reflection with one finger.

I finished breakfast in silence, then left her there, still staring down at herself in the table.

I found Thomas in the observation room, standing beside the broad window that offered the best view of Earth. He held a thick, leather-bound notebook that I recognised as one of Earlier Thomas's journals.

Dark circles lay beneath his eyes. His beard was threaded with grey that had not been there when we arrived.

"She's getting worse," I said.

Thomas did not turn from the window.

"I know. Today she thinks Harwell Control is sending an extraction crew. Yesterday, it was her parents coming to visit." He sighed. "She's slipping away faster than I expected."

I joined him at the window. Earth hung against the blackness, blue and white and so far away that looking at it hurt.

"Anything useful in those?" I asked, nodding towards the journal.

Thomas turned to me, unease clear in his face.

"I know why we're here," he said. "The anomaly isn't natural."

He handed me the journal, open to a page covered in Earlier Thomas's neat handwriting. Diagrams filled the margins: cross-sections of the lunar surface, Shackleton's foundations and the faceted object embedded in the floor of the maintenance room.

"The original construction team uncovered something beneath the surface and brought it up," Thomas said. "Something that fractured time."

I skimmed the page while he continued.

"They were drilling a thermal bore twenty-four metres beneath the outpost when they struck a metallic object where no metal should have been. It appeared artificial, but its composition was unknown. Isotope analysis of the material and examination of the surrounding strata produced no meaningful age. Its electromagnetic readings exceeded the range of their instruments. Command ordered them to extract and study it despite objections from the science team."

"Keep reading," Thomas said.

I followed Earlier Thomas's notes.

The first temporal distortion had been recorded sixteen hours after extraction. At first, it had seemed minor: equipment failures, sensor readings appearing before the instruments took them, and communication delays that could not be reconciled with the distance to Earth.

By the third day, members of the construction crew were reporting severe deja vu. On the sixth day, two of them encountered versions of themselves in corridors that had been empty moments earlier. The indistinct figures we had glimpsed through Shackleton's windows were the same kind of temporal after-image, not additional living occupants.

I looked up at Thomas. "Christ."

"They knew something was wrong," he said, taking back the journal. "They tried to return the artefact to the bore and bury it again, but by then the distortion had taken hold."

"What about Harwell Control? Earth? Why didn't anyone send help?"

Thomas turned several pages.

"Communications became unreliable. Messages arrived before they had been transmitted. Others were altered or repeated in voices belonging to people who had never sent them. Terrain masking and their limited relay equipment caused ordinary gaps, but the later failures came from the anomaly itself. Eventually Earth appeared to stop responding altogether, at least from the perspective of the crew inside the field."

"What happened to the original crew? The people who found it?"

"According to these records, they died trying to destroy or remove it. They used explosives, attempted to drill through it and tried to load it aboard a vehicle so they could launch it away from the Moon. They even attempted to lower it into the bore again. Nothing moved it. Nothing damaged it."

Thomas closed the journal.

"That was the first loop. Since then, the anomaly has drawn in variations of the same three-person expedition. Earlier Thomas's notebook combines inherited records with memory bleed from previous iterations. He didn't personally experience nineteen ordinary lifetimes here, but between the surviving journals, handwritten fragments and what came through in his memories, he identified nineteen distinct cycles in all."

My stomach lurched.

"Nineteen," I said. "That's what Earlier Daniel wrote on the wall. Daniel 18 and Daniel 19."

Thomas nodded. "The eighteen archived log sets belong to completed cycles before this one. We are the nineteenth trapped crew. Each iteration differs slightly, but the sequence always converges on the same ending: three deaths, then three further deaths by choice. After that, the system resets."

"And no crew has ever broken the pattern."

I paced beside the window, trying to absorb it.

"But if we know the pattern, we can change it. We can do something different."

"Such as what?" Thomas sounded exhausted. "Earlier Thomas tried everything he could think of. So did the people whose records he inherited."

"There has to be something," I insisted. "Some variable they failed to account for."

Thomas placed the journal on a nearby console.

"I've spent weeks reading these. Earlier Thomas was thorough. He recorded every attempt, theory and failure that survived. The artefact cannot be moved, destroyed or removed from Shackleton. The loop cannot be broken by any normal physical means."

"Then we need to try something abnormal," I said, desperation sharpening my voice.

Thomas reached into his pocket and placed two pre-filled morphine syringes from Shackleton's controlled medical stores on the console between us. They were the ones Earlier Thomas had prepared before asking for our help. Thomas pushed one towards me.

"Enough morphine to stop our hearts," he said. "We die on our own terms, not as part of its design."

I looked at the syringe with Earth framed in the window behind it.

"You think killing ourselves will break the loop? Earlier Eleanor did that. Earlier Thomas chose death as well."

"Not to break it," Thomas said quietly. "To deny it the satisfaction of watching us disintegrate as they did. To choose our ending instead of having one forced upon us."

I picked up the syringe and weighed it in my hand.

"What about Eleanor?"

"Already done," he said, and his voice cracked. "She asked me to help her an hour ago. She's gone, Daniel."

The words struck with physical force. I sank into a chair, still clutching the syringe.

"Gone? Just like that?"

Thomas nodded.

"She came to me in tears, lucid for the first time in weeks. She said she couldn't tell which Eleanor she was any longer. Earlier, present, future - they were all blending together in her mind. She asked me to help, and I did."

I remembered Eleanor at the galley table, touching her reflection. I remembered the distant look in her eyes. Our conversation that morning took on a different meaning. She had known she was leaving, only not in the way I had imagined.

"You should have told me," I said. Anger flared, brief and fierce. "I could have said goodbye."

"She didn't want that." Thomas sat opposite me. "She said it would be harder if you tried to talk her out of it."

I looked down at the syringe. My anger faded almost as quickly as it had appeared.

"So this is it? We simply stop fighting and let the loop win?"

"The loop wins whatever we do," Thomas said. "But this way, we go peacefully and together. Not alone and broken as they did."

Through the window, Earth continued its slow movement across the lunar sky, indifferent to our fate. Somewhere there, people were going to work, falling in love, growing old and doing all the ordinary things we would never do again.

"Will we remember when it resets?" I asked.

Thomas shook his head.

"I don't know. Earlier Thomas believed memories could bleed between cycles, just as handwriting and separate inorganic objects sometimes persisted. He had no concrete proof of conscious recall."

I rolled the syringe between my fingers.

"And you're sure this is the only way?"

"I'm not sure of anything any more," Thomas admitted. "But I'm tired, Daniel. Tired of fighting something I can't see or understand. Tired of watching history repeat itself."

We sat in silence for several minutes, each lost in our own thoughts.

At last, I nodded.

"All right. Let's do it."

Thomas moved his chair beside mine. We sat shoulder to shoulder, facing the window and the distant Earth.

We rolled up our sleeves and placed the needles against our veins.

"On three," Thomas said. "One, two..."

I drove the needle into my skin and depressed the plunger, feeling the cold morphine enter my bloodstream. My last thought was of Eleanor. I wondered whether her body had already faded, whether the sheet and her clothing had gone with her whilst the spent syringe remained behind.

Then darkness took me.

I opened my eyes to the steady beeping of the lunar lander's instruments.

White noise from the navigation system filled the cabin, rhythmic and alive. Thomas sat at the command console, conducting the pre-approach checks with his customary precision. Eleanor occupied the pilot's seat, her dark auburn hair secured in a practical plait, her hands moving confidently across the controls.

They both looked younger. Rested. There were no shadows beneath their eyes, no gaunt cheeks and no distant, hollow stares.

My mind struggled to reconcile what I saw with what I remembered. Seconds ago - or had it been months? - I had been sitting beside Thomas in Shackleton's observation room, injecting morphine into my vein. I remembered the cold liquid entering my bloodstream. I remembered the darkness.

Now I was back aboard the lunar lander, forty minutes from Selene Station, exactly as we had been three months earlier.

Or moments earlier.

I touched my face. I was clean-shaven. I examined my hands. There were no abrasions from repairing Shackleton's failing equipment, no ingrained grey regolith from scraping together a shallow covering for a body we could not properly bury. My uniform was crisp and new, without the worn patches and stains left by months of continuous use.

"Approaching final orbital adjustment," Eleanor announced without looking away from her instruments.

Thomas checked his display and nodded.

"Perfect. Right on schedule."

I tried to speak, but no sound came. None of this was possible, yet it was happening. My mind raced through explanations: a dream, a hallucination caused by the morphine, the last convulsion of a dying brain.

Everything felt too real. The hard seat beneath me. The whisper of the air-recycling system. The distant vibration of manoeuvring thrusters keeping us on course.

Thomas's console chimed with an incoming transmission.

"We're receiving a message," he said, reaching for the communications control.

Realisation struck. I knew what the message would say before he opened the channel.

"Selene Expedition 27, this is Harwell Control. We have a situation at Selene Station. Coolant contamination has compromised the primary habitat. You are being diverted to Shackleton Outpost until we can confirm Selene is safe. The diversion will add one hour and fifty minutes to your flight. New coordinates are being transmitted now."

The voice was perfectly clear, carrying no static or distortion. It sounded exactly as Harwell Control should have sounded, but I knew now that the transmission originated from Shackleton. The anomaly was impersonating Harwell Control and closing its own causal loop.

Thomas acknowledged the message whilst Eleanor began entering the new coordinates. Neither of them appeared troubled by the change because they did not know. They could not remember.

Terror seized me as I understood what had happened.

The loop had reset. We were back at the beginning, about to make the same decision that had trapped us in that nightmare for months.

"We can't go to Shackleton," I said. My voice emerged as a croak.

Thomas and Eleanor turned towards me.

"What did you say?" Thomas asked.

"We can't go to Shackleton," I repeated, louder now, forcing myself out of my seat. "It's a trap. There's something there, something that fractures time."

Concern crossed Thomas's face.

"Daniel, what's wrong? Are you feeling unwell?"

"No, listen to me." I moved towards the command console on unsteady legs. "I've been through this before. We all have. Shackleton isn't abandoned. There's a temporal anomaly beneath it. If we descend, we'll be trapped in a loop."

Eleanor stopped entering the coordinates. Her eyes widened.

"Daniel, you're not making sense."

"There's an artefact under the outpost," I continued, the words spilling out. "A faceted object roughly the size of a football. The original construction team uncovered it while drilling a thermal bore twenty-four metres down. It's metallic and artificial. It fractured local time and created the loop. Nineteen cycles have already occurred. This is the twentieth descent."

Thomas rose and placed a steadying hand on my shoulder.

"Daniel, sit down. You may be experiencing some form of acute neurological episode."

I knocked his hand away.

"I'm not ill. I remember everything. Shackleton, the earlier crew, their deaths. Earlier Daniel, Earlier Eleanor, Earlier Thomas. They died, and then we did the same. Eleanor died first. You helped her. Then you and I took morphine in the observation room. You gave me one of the syringes. I injected myself, and then I woke up here."

Concern gave way to alarm. Thomas glanced towards the medical kit.

I lunged for the communications console and pushed past him. I had to warn someone, anyone who might listen.

"Harwell Control, this is Daniel Mercer aboard Selene Expedition 27," I shouted into the microphone. "Shackleton Outpost contains a temporal anomaly. Do not divert us there. Repeat, do not send us to Shackleton."

Only static answered.

Thomas pulled me away from the console.

"That's enough."

His voice had hardened into command authority.

"Eleanor, prepare a sedative."

"No."

I twisted out of his grip.

"You have to believe me. This is the twentieth cycle. It never ends. Six people die every time - three earlier counterparts, then the three new arrivals. Then everything resets."

My gaze fell upon my station. A paper notepad lay open beside the systems monitor.

I had not used it during the flight. We had been aboard the lander for only a few hours.

Yet every page was covered in writing.

My writing.

I snatched up the pad, my fingers trembling. It contained calculations, diagrams and warnings in my hand, but not quite as I wrote now. The script was more hurried, its lines sharp and cramped. It was the handwriting I had developed after months of fear and exhaustion at Shackleton.

Memory bleed made physical. Handwritten material persisting where digital records failed.

At the top of one page, two entries had been boxed: DANIEL 18 and DANIEL 19. Beneath them, in heavier strokes, was a third warning: YOU ARE DANIEL 20.

"Look at this."

I thrust the pad towards Thomas.

"I didn't write this. Not yet. But it's my handwriting - what my handwriting became at Shackleton."

Thomas glanced at the pad, then back at me.

"Daniel, please sit down. You're having some sort of psychological episode."

"Read it," I insisted. "It explains everything: the anomaly, the loops, the deaths. It's all there."

Eleanor appeared beside Thomas with a syringe in her hand. The sight triggered a violent flash of memory: Thomas and me sitting before Shackleton's window, another needle against my arm, morphine entering my vein.

I backed away from them.

"Please. Read one page. If it doesn't convince you, I'll accept the sedative."

Thomas hesitated, then nodded.

"One minute."

He took the notepad and began to read. His expression shifted from scepticism to confusion, then to unease as his gaze travelled down the page.

"These are detailed schematics of Shackleton," he said. He turned another page, then another. "And calculations relating to temporal displacement."

"Yes." Relief flooded through me. "Everything we learnt in the nineteenth cycle is there."

Eleanor looked over his shoulder.

"It does resemble your handwriting," she said. "But it's more frantic."

"Because I was frantic. We all were. We were trapped in that outpost, watching the same pattern repeat, learning that we were only the latest iteration of the same crew."

Thomas lowered the notepad. His face was grave.

"Even if what you're saying is true - and I'm not saying I accept that it is - what can we do? Harwell Control has ordered us to Shackleton."

"Ignore the order. Continue to Selene. The coolant contamination is fabricated. There was never anything wrong with the primary habitat. The message came from Shackleton, using Harwell Control's voice."

Eleanor shook her head.

"We cannot disregard a direct operational order without verifiable cause."

"This is cause." I pointed at the notepad. "This is proof."

"It isn't proof, Daniel," Thomas said gently. "It's a notepad containing writing we cannot explain. That isn't sufficient grounds to disobey Harwell Control."

I dragged both hands through my hair. They were not going to believe me. Of course they were not. Everything I said sounded deranged. I would not have believed it either before living through it.

"Then contact Selene directly," I said, trying another approach. "If there really is coolant contamination, the station crew will confirm it."

Thomas considered this, then nodded.

"That's reasonable. Eleanor, attempt to raise Selene Station."

Eleanor returned to the communications console and began transmitting.

"Selene Station, this is Selene Expedition 27 requesting a status update. We have been informed of coolant contamination in your primary habitat. Please confirm."

We waited.

Static hissed from the speakers.

Eleanor tried again.

"Selene Station, this is Selene Expedition 27. Please respond."

More static. I had known there would be no answer. There never had been.

"Try the emergency frequencies," Thomas said.

Eleanor switched channels and repeated the call. Nothing returned but noise.

"This does not prove you're right," Thomas told me. "Selene may be below the local horizon, the relay may be unavailable, or the contamination may have affected its communications equipment."

At least he had not dismissed the silence as ordinary lunar interference. I knew the anomaly was responsible, but I could not prove it from inside the lander.

I went to the nearest viewport and looked down at the lunar surface as we crossed our orbit. In the distance, a geometric patch caught the sunlight.

Shackleton Outpost.

"There," I said, pointing. "Look at Shackleton."

Thomas and Eleanor joined me at the viewport. As we watched, tiny points of light appeared across the supposedly mothballed complex, visible even from orbit.

"That's odd," Eleanor murmured. "Shackleton was mothballed four years ago."

"Those are the lights coming on to welcome us," I said quietly. "Just as they did before. Just as they do every time. The outpost will report life support for exactly six occupants before we meet our earlier selves."

Thomas stepped back from the viewport, visibly unsettled.

"I still don't understand how any of this could be possible. Time loops, duplicated crews... It contradicts every established physical model."

"I know," I said. "We never learnt exactly how it works. We only learnt that it does."

Eleanor returned to her controls and checked the flight data.

"We need a decision shortly. We're approaching the point at which we must begin the descent manoeuvre."

Thomas looked from her to me, command protocol warring with doubt in his expression.

"We've received a valid diversion order in Harwell Control's voice, and we have no confirmed evidence that Selene is safe. Shackleton has power and life support. If Selene's habitat really is compromised, Shackleton is our only available shelter."

"The lights are on in an outpost abandoned four years ago," I said. "Isn't that evidence enough?"

"The systems may have activated automatically," Thomas replied. "Or Harwell Control may have brought them online remotely in preparation for us."

I could see that I was losing. Duty, uncertainty and the immediate need for shelter outweighed a notebook that should not have existed and the warnings of a science officer who appeared to be in crisis.

Eleanor's hand hovered over the controls.

"Commander Whitaker, your decision?"

Thomas drew a long breath.

"Set course for Shackleton as ordered."

"No!"

I lunged towards Eleanor's controls, but Thomas stepped between us. The cabin was too cramped to pass him, and command lockout prevented me from altering the pilot's flight path from my station. I could not seize control without physically attacking both of them and risking the lander before the descent had even begun.

"You're condemning us to the loop again."

"Daniel." Thomas's voice was firm. "I'm not dismissing everything you've said, but we need more information, and Shackleton is where we can obtain it. If your account is accurate, we will investigate the anomaly together. We will arrive prepared."

I knew that promise. Some version of it had probably been made nineteen times.

Eleanor turned the lander towards Shackleton with the same skill and confidence she had always shown. I sank into my seat, utterly defeated.

Through the viewport, the outpost grew larger. Its lights shone against the grey regolith. I could almost see figures waiting inside: our earlier selves, worn down by months in a fractured timeline.

I knew what would happen next. We would touch down safely about 3 kilometres from Shackleton. During the first scheduled sleep period, less than twenty-four hours after our arrival, an anomalous systems failure would rupture the lander's tanks in a silent flash. Brief propellant-fed combustion would die almost at once, leaving glowing fragments and venting vapour.

We would make the twenty-minute low-gravity walk to the outpost. We would discover it fully operational, apparently sustaining six people. We would find cold, tannin-stained tea in three enamel cups and ration pouches and biscuit packets arranged beside the galley heater. We would glimpse moving shapes through the windows and mistake temporal after-images for living occupants.

Then we would meet the three earlier versions of ourselves.

We would learn about the artefact. We would watch Earlier Daniel die in a defensive killing, Earlier Eleanor take her own life and Earlier Thomas ask for help to end his pain. Then our own crew would follow the established sequence: Eleanor, Thomas and me.

Afterwards, I would wake here again.

Or perhaps some altered version of me would wake. Daniel 21 instead of Daniel 20.

I took the notepad from where Thomas had left it and stared at the equations and warnings written by a hand shaped by experiences I had already endured but had not yet lived in this cycle. I had not written those words during this flight, but I would write them again at Shackleton, just as versions of me had done before.

The descent warning sounded.

I recognised the precise order of tones. I knew which instrument would change next, which figures would appear and when Eleanor's hand would move to the thrust control.

The display shifted exactly as I remembered.

"It's happening again," I whispered.

The lunar lander began its twentieth descent towards Shackleton Outpost, towards the waiting temporal trap that had claimed us again and again in its closed sequence of death and rebirth.

Beyond the viewport, the lunar surface rose to meet us. Eleanor's hands moved smoothly across the controls. Thomas watched the approach path.

Every instrument followed the remembered sequence.

The loop continued.