“Extinction Event” by Adam Carlton

Prologue: Mara

Its discovery was a remarkable accident.

The Spaceguard programme searching for Earth-impacting asteroids had been in progress for more than twenty years. In 2017, one of the Spaceguard telescopes, Pan-STARRS 1, discovered the first interstellar asteroid, ‘Oumuamua’. But that discovery came very late, almost as it was leaving the solar system.

Dr Mara Ayrton worked at Yale on asteroid early-warning. The usual method used a blink comparator with images taken ten minutes apart. The stars remained stationary; the asteroid, moving along its orbit, 'jumped' between the two images. It was a procedure which was easy to automate but depended on the asteroid actually being visible, being illuminated.

Mara knew that incoming interstellar asteroids were initially too far away, too dim to be seen. But there was another way.

She had pressed for the upcoming mission-design to search for stellar occultations. This would happen if the asteroid momentarily went in front of a star, blocking its light. Such a blink would last only for milliseconds: an asteroid's star-shadow is only its size, only miles across. The orbital telescopes - like the Earth in its own orbit - would flash through that in an instant.

Still, Mara insisted, at fifty frames per second such blinks could be caught. And astronomers were used to digitally adding thousands of frames together to build brighter images. Her proposal was accepted provided she agreed to develop the software.

Another stroke of luck. This particular asteroid came in from the constellation Scorpio. It passed in front of the globular cluster M80. Thousands of closely-packed stars cast a mosaic of spatially-clustered shadows, duly noted by the asteroid-hunting telescopes.

Mara's correlator, linked to a pattern-detecting neural net, went crazy. Alerts flashed across her screen, chirruped at her phone.

There was a protocol. Mara called her head of department who confidentially alerted the other observation platforms. Within twenty-four hours they had the details pinned down. It was indeed interstellar. It was big: bigger than the impactor which had killed the dinosaurs. It was travelling faster too, and had a very good chance of hitting Earth. Its impact energy would be 15-20 times that released at the Yucatán Peninsula.

It was death.

There was a protocol about that too. What to do next. It was idealistic.

It was stupid.

Mara's head of department called the United Nations.

Had anyone thought through the consequences? The likely popular response? The utter inability of the UN to keep a secret?

Major governments moved as one to clamp down on the end of the world. The first few reports were squelched, the presenters vanished. And behind the scenes, in conditions of the greatest secrecy, the powers of the world met in all their awesome pomp to consider the only question that mattered: what can we do?

They needed a name of course. It was customary to honour the discoverer. And so the asteroid was called 'Mara' - which means 'bitter' in Hebrew.

It is not recorded what Dr Mara Ayrton's reaction was.

The first the public heard was more than four years later, when - finally - a sombre announcement was made across all the countries of the world.

"We have ten months left. There is no hope."

The Policeman and the Priest

I wouldn’t normally post this, but what the hell, what does it matter anymore? Last night my lover, Brute, confessed to me, his second confession of the day. He’d heard the news, he said, and then he'd done something he hadn’t done since childhood. He'd gone to Mass.

The priest gave a sermon. God knows where he got it from. Brute said he was euphoric, inspired, speaking of the Rapture. The faithful were going to be uplifted to heaven.

I withdrew my arm from his chest and sat up.

“Listen,” I said, “It’s a space-mountain, a dinosaur killer. No-one is going to be ‘sucked up’.”

I’m the physicist. Brute is the policeman.

He defended his pastor.

“We don’t know that, not exactly. The priest said it was the anti-Earth. As foretold in the end-times.”

I snorted. An Earth-sized impactor would raise tides a hundred miles high. Would draw the atmosphere into supersonic winds. Forget bodies wafting skyward. Besides, we knew how big it was.

I sank back into the sheets, resignedly pulled up the duvet.

“What happened next?”

“I went to Confession.”

I raised my eyebrows in the darkness.

“When was the last time you confessed to a priest?”

I rubbed my fingertips through his curly chest hair.

“I didn’t tell him about us, what would be the point of that? No, I needed him to tell me what life was for now. As a Catholic.”

“And he had good advice, this rapturous priest?”

“He said that all moments exist in eternity. He asked me why I was a policeman.”

I was suddenly interested: “What did you say?”

“I told him the truth. I told him I hated injustice, that I despised the rich and powerful riding roughshod over ordinary folk like myself. Their only defence was the law I upheld.”

I nodded to myself. It reminded me of why I’d been attracted to Brute in the first place. One of the reasons.

“The priest said that all my acts, all my deeds were bricks in the wall of civilisation. That if the good outweighed the bad, if my intentions were pure, then I was part of God’s plan. Then he started to forgive me."

"Did you ...?”

“And then I interrupted him,” Brute exclaimed.

“Why?”

“I said: ‘Father, after the impact, there will be no people, no future. So how can my little life have any significance?’”

“And what did the priest say?”

“Nothing. He just concluded his blessing and sent me on my way.”

The next day I was on my way to the university - yes, life goes on and we still teach physics - when I saw that very priest spouting his ethereal nonsense on the pavement. Very Christlike. I thought the Catholic Church had abandoned all that long ago. He was in his robes, wearing his Jesus sandals and holding a staff.

I stepped into the road to avoid his small audience. I saw a uniformed policeman walk up, making his way to the front of the group where he knelt down and kissed the charlatan’s feet.

It was Brute. This was the man I shared my life with. Scales fell from my eyes. This was a man, I realised, I had never truly known. My stomach churned.

I bent over double and vomited into the gutter.

A Turbulent Priest

From the Paris Correspondent of The Guardian Online.

'At first sight it seemed just another service in a Parisian church but little about Saint Bernard de la Chapelle was ordinary. The presiding priest, Father Léopold Damas, had been a regular thorn in the side of the Church authorities with his liberation theology and militant leftism. I had received a tip-off to attend.

Saint Bernard was a beautiful old church in one of the poorest parts of inner Paris. The interior was bathed in light; billowing incense in the still air gave shape to the sunbeams. Fr. Damas spoke from the altar, his amplified voice echoing over the congregation.

Behind me I was surprised to see pews occupied by men dressed in the dark suits of Bastion Social, the fascist organisation with links to Opus Dei. They stood as if on parade, hands crossed in front of them, their presence impossible to ignore.

I was standing with the regular congregation, the aged, huddled people of the Goutte d'Or, this forgotten slum close to Sacré-Cœur. There were twenty or thirty of them listening with rapt attention to their minister.

Further forward, towards the priest himself, I noticed that the front two rows were occupied by burly men with red armbands. I recognised volunteers from the defence organisation of the Parti Communiste Français. There had long been rumours of a local, highly-unofficial alliance between the Red and the Black in this parish. Here surely was the evidence.

But with fascists to the rear and communists to the front, it was plain this Mass was a tinderbox.

Fr. Damas, in his old man's voice, was discussing eschatology. Despite Damas's firebrand reputation I was half-expecting the standard homilies but the presence of two hostile camps should have alerted me. This priest was never going to speak the orthodox clichés.

"Yesterday I heard a prominent atheist-biologist on television, an Englishman," he was saying, "The professor explained that - as we were all no more than atoms obeying the laws of physics - life was ultimately meaningless and we should therefore just get on and enjoy it."

There was a quiet hissing from the back rows.

"Yes, I believe in evolution ..."

At this there was more hissing from the back, louder now, and more chilling.

"All life is one. The dinosaurs were obliterated but their lives had purpose. In harmony with their nature they lived, reproduced and died as living beings always do.

"It's only people who agonise whether an ethical life is enough, whether we should be doing something more.

"And I say to you there is not. We should strive to cultivate our best and true natures, help each other and refrain from harm. And do this even if the skies will fall."

It was at this point the first stone was thrown. I could not see the perpetrator, somewhere behind me, just the missile's falling path. It hit the priest in the face, scouring a deep cut in his right cheek. Blood spurted over his white alb. His voice faltered but he persisted, duty-bound it seemed to get his message across.

"When this Mass is ended you must leave ...  not in despair ... face the end in peace ... death happens to us all ... God is in our better nature and we must seek him there ... ."

The flung cobblestone hit Father Damas in the head and knocked him flat. The assembly, the ordinary participants around me, began to flee into the aisles, bunching and jamming in their haste.

The PCF contingent turned as a disciplined phalanx to face the rear, returning fire using hassocks and prayer books, whatever was to hand.

Pushing and shoving, I made a dash to the exit at the rear of the nave. As I left the church a pitched battle was developing lit by the flickering flames from the first of the petrol bombs.

As I write this I see from the TV that the last bodies are being removed from the smoking ruins of Saint Bernard de la Chapelle, ending almost two hundred years of its sacred history.

The fate of Father Léopold Damas is currently unknown. His body was not recovered.'

Into the Fireball

I am posting his last letter on this, the last day. People should know what my husband is doing. The price he’s paying. We’re all paying.

---

Dear Nikki,

We said we were going to watch the end together. We said we would face the ocean, watching for that distant shimmer on the horizon. The incoming wave which would end our precious days together.

Even this consolation will now be denied us.

I am unbearably sorry.

I had to get this to you through a friend. He's going off-base and will email it to you - against regulations. We are on lock-down: from now to the end.

I could not believe the orders the squadron was given. An hour before the asteroid arrives we’ll deploy into the west, flying out over the sea towards the setting sun. Twenty five miles separation. A chain of aircraft, heading for the impact zone, linking back to Edwards Air Force Base.

The information must get back.

The asteroid will enter the atmosphere over America, flying towards the Pacific. It will go over our heads. My aircraft - the lead plane - is instructed to fly directly into the fireball, with the others following.

Our F-35s have been modified. We’re carrying every sensor imaginable. This will be the most observed asteroid impact in history.

Why? What is the point?

We asked ourselves that as we left the briefing room. Talked amongst ourselves. The United States Air Force does not do suicide missions. We are not kamikazes. That’s what we told ourselves.

Someone said, “What’s the point of this operation? Everyone’s gonna die regardless.”

Someone else said, “That’s the military for you. I’ve had some stupid orders over the years ... but this ... to take us away from our wives and families.”

That was my view as well. We were all feeling pretty bad. The mission seemed senseless. We asked questions and got no answers.

That night - this was just a day ago - I was lying on my cot brooding. I knew there would be no more time for reflection. Just days of exercises and preparations, and then we would fly the mission. So I lay there, and really thought.

Nikki, there can be only one reason for this mission. They will never tell us but there must be a plan… Somewhere a group, perhaps buried under the biggest mountain they can find, is preparing to survive. They will have to stay safe for years. I’ve seen the scenarios - the Earth does not recover. They will have to use those years to prepare - somehow - to come out and survive in the aftermath.

Impact information will be priceless. They can refine the computer models; predict the climate collapse, the far-distant recovery, the total energy dumped on the planet.

That’s why we’re flying.

And that’s why I can’t come home.

Nikki, ...

---

The rest of the letter is kind of personal.

If you read this, please remember us.

All my love,

Nikki

XX

A New Star

It was a bright dot in the east as I left my apartment. A new star. Cold and motionless.

I wasn't fooled. It's interstellar, they said, which accounts for its excess speed and energy; if you can see it, it's close. It will hit the Pacific in a few hours.

The San Andreas Fault will probably go first. California will crumple into the sea before the tsunami strikes. The Rockies should block the flood before it reaches Cheyenne Mountain. Not that we would care, buried as we are in the NORAD command centre. The safest place in the world.

We’re invulnerable.

My name is Katy Thompson. I am a Communications Security Engineer at the Cheyenne Mountain Complex. I have the highest security clearance.

And I am invisible.

And this is the last day.

The global Internet is still working. This is the greatest achievement of mankind: the largest, most complex, most sophisticated, most reliable machine ever created. Engineers like me have kept it working, acolytes at the altar of humanity's nervous system.

We are still a global community.

I'm at my desk. There's half a mile of mountain above me. They say we could work here undisturbed while a nuclear war raged outside, a war in which we would be a target. This will be tested for the first time during the next few hours.

Every meeting here is securely recorded. Everything. I don't think the generals and the politicians really know that. It was an early decision in the security architecture.

Someone has to review those recordings. For classification and quality control. Someone invisible. Katy Thompson. Me.

I understand that you who are reading this have gone through every stage of grief. That you are abandoned to despair. That you accept that there is no hope.

You watched all the options paraded in the media. The prudent ones. The far-fetched ones. You felt your hopes rise: something of us will survive! And then those hopes were cruelly dashed, shot down by experts armed with the ring of truth.

And so you are resigned, not just to personal extinction but to the loss of all you believe in. Everyone you hold dear. Everything that has ever been achieved. The extinction of the world.

And so I break the rules of a lifetime. Betray my duty. And post this ultra-secret transcript of a meeting that took place five years ago. Post it to the public Internet.

I could find no records at all of any follow-up. I don't know if Plan Z was ever executed.

This is all the hope we have.

Beyond Secret

It was beyond secret. A meeting held 2,000 feet inside Cheyenne Mountain, the nuclear war command centre for NORAD, the North American Aerospace Defense Command.

In the diary it was itemised as ‘Scenario Briefing’, the blandest title they could find.

The President was difficult to manage: volatile and aggressive with a short attention-span. Bill Patterson knew he would be walking on eggshells. The meeting was as small as possible. Just the science advisor, the President and the Secretary of Defense, a thin, birdlike man who could pass for an actuary. This was three weeks after the discovery of the impactor.

“Mr President, Mr Secretary, three weeks ago our Spaceguard network discovered the asteroid on a collision course with Earth. As you know, the predicted impact is five years away. I was asked to convene a task force on mitigation, reporting as soon as possible. This meeting constitutes my report.”

The President looked interested. His florid face was that of a man who much preferred activity to sitting in a chair. But if he had to listen it had better not be boring.

The Defense Secretary expressed his concern at the lack of a written brief.

“Mr Secretary, for reasons you will shortly hear, this is a verbal briefing only. Governments already enforced a global blackout on the impact itself. We all know the reasons for that. But what I am going to tell you today is far more important. It must not go beyond this room. There must be no leaks.”

Patterson had their full attention.

“You will already have seen the classified forecast on the event itself. It will be far bigger than the Yucatán impact. The asteroid will dig a crater 20 to 25 miles deep. The rebound will eject a fan of molten rock beyond the atmosphere spreading like an aerosol. That will re-enter - to fall on the entire surface of the world.”

Patterson shaped his hands, sculpting a soccer ball.

“Gentlemen, from horizon to horizon, to look at the sky will be to look into the maw of an erupting volcano. The land will burn, the oceans will boil.  If the worst happens, and it lands in the Atlantic or the Pacific, a mile-high tsunami will cross our coasts and scour half our country down to bedrock.

“Let me repeat what you've already been told. This is an extinction-level event. In the firestorms and in the freezing aftermath, almost all plants will die, all large animals will die. The Earth’s ecology will stop in its tracks.”

The President didn’t seem fazed by this cataclysmic prospect, seeming to relish it more as a challenge.

“This is America. We can do this, right? We can get some Americans through this, the best of the best, and rebuild on the other side.”

He gestured around the room.

“They tell me this place can survive a 30 megaton nuke just a mile away. That people here could survive a nuclear war. Just tell me what you need and you get it.”

So this was Patterson's job here, to lead his distinguished audience down the ladder of increasingly-unpalatable options.

“You're describing Plan A, Mr President. You’ll hear about it soon from our Survivability Task Force. They’ll tell you: sea, bunkers, space. They’ll tell you that people in nuclear submarines, deep in the vast oceans, will survive the impact; that bunkers distant from the impact site will remain secure; that people sufficiently distant in space will be insulated from its effects.”

The President nodded: it sounded plausible.

“We can even provide enough supplies to wait out the immediate aftermath. The toxic air, the climate-collapse, the nuclear winter. After five years, plus or minus, it might be safe to come out on the surface, at least with breathing apparatus. But what then?

The Secretary of Defense said, “And then we rebuild.”

“Unfortunately, Mr Secretary, we can’t. I need to emphasise this. The global economy has collapsed - almost everyone is dead. There are no trees, no flowers, no visible animals, few insects and no useful ones. No fuel to power machines, crops will not grow, the climate will have changed utterly.

“It’s tempting to think that after the supplies run out and we’re done with scavenging - and by the way, there will be precious little lying on the scoured surface - it’ll be like the Waltons, homesteading in Virginia."

The President smiled. That had been one of his favourite shows.

“Nothing will grow,” Patterson insisted, “Crops we plant by the sweat of our brow will die. The soil has been removed, or is poisoned. There are no birds or insects to pollinate. Agriculture will not be possible for tens of thousands of years. After the Yucatán impact the Earth became Fern-World for millennia. I repeat: once their supplies run out, the survivors will starve.”

“Well, if we have to, I guess we’ll get back to hunting and gathering, like the Native Americans did,” observed the President.

Plan Z

Patterson sighed inwardly, and tried to console himself. He had had longer to think about these things than his audience.

“Mr President. There are no animals left bigger than rats, and they exist only in a few protected habitats. What the ecologists call refuges. There are no plants to feed on, only the remnants of rotting vegetation. There are almost no fish in the sea - the plankton which holds up the food chain has died. Our survivors will see a sterilised landscape.”

He felt their concentration. There's something about disaster scenarios which fascinates everyone.

“How can I put this? In biological terms, human beings are large animals at the top of the food chain. There will be no ecological space for such animals. After the dinosaur extinction, large animals had to re-evolve; they didn’t come back for five million years. That’s how long it took the ecology to recover.”

The Defense Secretary objected.

“We can kick-start the process. Biobanks. Things like that.”

“Yes we can. That’s Plan B. You’ll hear a lot from the Recovery Taskforce currently putting together their proposals. Unfortunately, the food chain starts with plants. And they will not grow in the post-impact world. It will take millennia to re-green the Earth, to recreate the soil, to get basic things like grass and wheat and barley and oats to grow and reproduce. One problem I’ve already mentioned: pollinating insects barely exist.”

The Defense Secretary considers this, muses.

“We can’t store people for hundreds or thousands of years, can we?”

Of course not.

Patterson breathes a sigh of relief. They’re getting it. Finally he can move on. Begin to broach the unthinkable. But first to summarise and remove any remaining illusions.

“Gentlemen. The impact transforms the Earth into an alien planet, one which will not support life beyond scavengers and the eaters of detritus. Terraforming it will take centuries, millennia, even under the best conditions.

“We took submissions from people who wanted us to build a generation-ship, like those starships which take ten thousand years to cross the interstellar gulf. Some suggested we build a relativistic spacecraft and loop it round the local group of galaxies: subjective-time thirty years, universe-time ten million years. Come back when the planet’s healed. That was Plan C.

The President said with renewed interest, “Can we do that?”

Patterson shook his head. "No. No, we can’t."

“OK. I think we get the picture,” said the Secretary of Defense, “This event is unsurvivable for the human race. We can get some folk to live through the impact but building a sustainable population in the aftermath is impossible. The post-impact Earth will not sustain human life. Is that what you’re saying?”

Patterson nodded slowly. A good synopsis.

“Well,” said the President, “Assuming we’re not wasting our time in this meeting, what is it you’re proposing?”

Bill Patterson took a deep breath. This was the point he had been dreading. He is no salesman, and this is the most difficult sale in history.

“Let’s go take a coffee,” he said.

The President and the Defense Secretary left together, talking quietly. Patterson got himself off to the restroom. Sat in a stall and shut the door. Peace.

Trapped in Amber

It's a considerably subdued pair who re-enter the conference room. The President, who Patterson thinks lives in the moment, seems - incredibly - to have treated the whole issue as something of a lark up to this point.

The Defense Secretary with his bureaucrat’s heart has failed, Patterson thinks, to raise his eyes to the bigger picture. But something has changed.

“So let’s get this straight,” says the President, “What you’re saying is that a hundred years from now, give or take, there will be no more people, period? That despite anything the United States of America can do, we’re finished?”

“That is exactly right, Mr President. There are no loopholes. There is no way out. Perhaps if we'd had a self-sustaining Mars colony ... but the asteroid has come too early.”

And now to engineer the topic-shift: gently does it. This will be a hard sale.

“Do you remember, gentlemen, that scene in Jurassic Park?” says Patterson, “They get dinosaur DNA from a mosquito trapped in amber. One that had fed on a dinosaur’s blood?”

The President smiles, he remembers it.

“Everybody rubbished it from a scientific point of view. Until they started to sequence Neanderthals. Bodies a million years old. The problem is that DNA degrades with time. It needs extreme cold to preserve it.”

Patterson pauses, gently does it.

“And we have the Amundsen–Scott South Pole Station, sitting on 9,000 feet of ice atop bedrock.”

He waits to see who’ll run with this. Come on!

It’s the Defense Secretary.

“You’re suggesting storing human DNA samples in the ice in Antarctica?”

“Essentially, yes. We have five years. We can get a lot done! We can transcribe the genetic code of key individuals and animals into indestructible plates. We can write a primer on how to decode DNA. We can give helpful hints on bringing them back.”

The President nods, “You mean, like the hairy mammoth?”

Yes, exactly like the hairy mammoth.

“Of course,” says Patterson carefully, “we only get one shot at this. One only. We need to make this as easy as possible. The mammoths were found frozen in the permafrost. This works best if we get human beings and preserve them whole in the Necrosphere. Give the reincarnation engineers all the information we can.”

“What did you call it?”

The Secretary of Defense sounds alarmed, his academic calm finally jolted, a surprise too far.

“The Necrosphere. That’s what we’re calling it. A giant hardened sphere, maybe two hundred feet across. An ark across time. Millions of years. Frozen people, frozen plants and animals; records and manuals. A time capsule ready to be reborn. When the conditions are right.”

The Defense Secretary works to restore his competent, slightly-bored persona.

“And this - time-capsule - will survive the impact?”

“If Plan Z is approved, gentlemen, then I assume there will be unlimited resources. We will build the sphere here in the US, transport and assemble it at the South Polar station and sink it into a deep trench. It will have heating elements in its outer skin. The ball will melt its way two miles to the bottom of the ice. We’ll sink markers around it, radius maybe half a mile. Scanning anomalies: dense metal, radiation sources, obvious artefacts. Things which shouldn’t be there.”

The President works to connect the dots.

“You’re saying anyone capable of resurrecting people should at least be able to do deep scans through the ice.”

“Yes, Mr President. That’s a kind of gate-keeping thing. If they can’t even find the Necrosphere, they’re unlikely to be able to open it, or do human cloning. “Of course, in seventy million years the ice-caps may have vanished anyway.”

It’s the President who asks the killer question.

“Who’s going to be doing the resurrecting, Mister? Space aliens?”

Those Who Come After Us

Patterson has been waiting for this question, has his crafted reply ready.

“We’re not planning on the assumption of space aliens, Mr President; we’re looking at natural processes. It took sixty-six million years to get from small, scavenging rubbish-eaters to people who can almost clone themselves. I’m suggesting we give the biosphere a fighting chance.”

What is Patterson talking about?

“We will build survival arks regardless of all you've heard today. How could we not? We'll re-engineer our nuclear submarines, re-purpose bunkers like this, we'll do something ambitious in space. There’ll certainly be humans alive post-impact. But they will all sadly die - leaving no descendants."

Patterson takes a breath. Here is the ultimate brutal truth.

"Gentlemen, I already explained that the post-impact Earth is an alien planet. It cannot support human beings. However, it can support some kinds of animals. Smart, questing, rapidly-reproducing omnivores low in the food chain, scavengers of what's left. We can kick-start a future ecology - it's just one that doesn't have space for us: not directly, not immediately."

His audience is puzzled. Once again they don't see where this is going at all.

“Our gift to the future will be biology. Carefully-optimised rodents. Hundreds of thousands of small mammals bred to thrive on post-impact Earth. We’ll edit-in some human genes. For intelligence and cooperation. Something of us will survive.

"We have five years to get it right, to fast-track their evolutionary path. Don't forget. This has already happened! But last time it took tens of millions of years. We can do better this time.”

And again Patterson stops. He has given them all the facts. They have to draw the final conclusions for themselves.

The Secretary for Defense with dry, immaculate logic tries to put it together.

“So let me get this straight. This is Plan Z? You’re asking for a Presidential Directive to design our evolutionary successors?”

Patterson nods. Mouths a yes.

“And you hope that after millions of years, they will bring us back?”

Patterson spreads his arms.

“Mr President, Mr Secretary. Understand that this is the last throw of the dice. Apart from this there ... is ... no ... hope. We are dead men walking. We are about to become extinct.”

He takes a deep breath.

“If anyone ever finds out, Plan Z will fail. You can imagine the responses: ‘America bio-engineers rats to take over the world’. The ridicule, the horror, the disbelief. How many supporters would it have? None. None at all.”

He’s talking to two politicians. They look at each other. Now they know why this meeting is beyond secret. Why Plan Z will be wrapped up in lies without end. No-one must ever know the truth.

“And it gets worse,” says Patterson, knowing that all the cards must now be on the table.

“We need at least one hundred and fifty people of all ethnicities. To provide genetic variation for a sustainable future population down the timeline. Those people need to be medically prepared and placed in special pods. They need to be properly frozen - without tissue damage - and then the Necrosphere sunk deep in the ice weeks before the asteroid arrives.”

He looks at their stunned faces.

“Yes, gentlemen, we’re going to have to euthanize those people well before impact. And for all the obvious reasons, we cannot tell them. Ever.”

He speaks quietly now and mainly to himself: “The lies will never cease.”

Plan Z will get the green light of course. Truly it is the last fling of the dice. But there is no alternative.

None at all.

And Patterson has a choice to make himself.

He had discussed it three weeks ago with his wife Patricia, when the news broke - against all regulations.

His daughter, Alicia, will be 18 at the time of impact. She’s of good stock; he could probably swing it.

His wife had taken his hand in her own and said dreamily, ‘We’ll be standing on the porch of our ranch in Wyoming: Alicia, you and me. We’ll watch it together, holding hands. We’ll watch the sky turn red, and then perhaps we’ll go inside and wait for the end.’

But in Bill Patterson’s mind there’s an alternative. Patricia and himself sure, on the porch awaiting Armageddon. While the corpse of their daughter lies on a cot in a metal sphere, one thousand feet beneath the ice and sinking still. Perhaps to wake again in an unimaginable future.

Almost certainly not.

His daughter would never know the truth. The protocol would not permit it.

But his wife would. And would she ever forgive him?

And would that even matter?

Not Happenstance; not Coincidence

Bill Patterson thought the meeting had finished when he packed his briefing materials and departed. He could not have been more wrong.

After a brief break, the President and the Secretary of Defense are joined by the Chairman of the Joint Chiefs of Staff, General Arthur Taylor.

General Taylor is a thoroughly modern soldier. Now in his fifties, he had flown ground attack aircraft in those endless middle-eastern wars. He had led the new Space Command. He had shown himself open-minded and imaginative in addition to possessing the necessary martial virtues.

All of his creativity has been tested to the limit by this unexpected challenge. What he confidently believes will be his last assignment. He had of course listened in to the previous briefing from a parallel room. There had been no need to spook Patterson by giving him a larger audience. In any event he was familiar with the details. Only the politicians had been out of the loop until the final briefing.

As he takes his position at the front of the small briefing room - the spot Patterson has so recently vacated - Taylor breathes deeply to steady himself, reflecting that fantastical as the previous meeting had been, this is going to top it.

“Mr President, Mr Secretary,” he begins, “This presentation is entirely complementary to the plan outlined by Dr Patterson. The US Military was also asked to do a crash study on the implications of the projected asteroid strike. I will now present the results.”

The Defense Secretary has not been party to what the Chairman of the Joint Chiefs is about to say. He waves his hand with a degree of irritation.

“General, we are in close contact with the Governments of Russia and China, as well as our allies. We are working together and sharing our preparations. We can all see we're in this together. I don't think we should spend too much of our time worrying about national defense at a time like this.”

His tone of voice conveys that time is short and he has much work to do.

The President is less impatient. His duties are less well-defined… and he always enjoys a talk by the military.

General Taylor moves to suppress any qualms.

“In the military we deal in capability not intention. If someone can do harm to us, we plan on the assumption that one day he might well do it. And so we prepare, no matter how smiling and friendly our adversary may appear to be today.”

“A well-known philosophical point,” mutters the Secretary, still impatient to leave.

The General persists.

“When the news was announced, even as the security blanket came down, we put a team together as did every serious military organisation.

“It didn't take long before we realised how unlikely this whole catalogue of events actually was. Think about it. We detect an asteroid with just the right parameters to eliminate all higher forms of life. And it just happens to be on a collision course for Earth. We did the math assuming a prior distribution of random intercepts of the solar system. The probability of this happening by chance is essentially zero.”

There have been too many shocks this morning. The President's mouth hangs open. The Secretary of Defense looks stunned. A man who prides himself that he's always one step ahead of the action, he has never considered this possibility. Never. Not once.

“I'm going to keep this brief, gentlemen, because all we need from you today is a green light. You will get more detailed proposals down the track. They are going to be very expensive but you are going to want to make very sure that that doesn't matter.”

The President, still disoriented, waves his hand. Continue. Please.

“Our highest probability scenario, an order of magnitude by the way, is that the Mara asteroid is not an unlikely accident at all but a hostile act. A civilization-killer. A species-killer. A real-estate grab.

“We expect that some years after the impact, we can't know how many, some kind of incursion will present itself. A probe bearing an alternative biological package. The new inhabitants of Earth. It's ruthless but it makes sense.”

The Secretary of Defense grasps at implications.

“So Patterson's proposal: let the biosphere recover, the work of ten million years; kick-start evolution to smarter animals; bring us back later - maybe. None of it's going to happen if we're taken over, is it?”

Taylor nods.

“Plan Z is finished before it even gets started if we permit an incursion. It sounds like science-fiction, but hell, in a few hundred years time we could run this scenario. If there was a planet we particularly wanted and we were desperate enough”

The President shows his legendary resilience.

“You're the Military. Give me proposals, General!”

Taylor smiles showing his gleaming white teeth, says formally:

"The US Military has determined that we face an existential threat from hostile actors unknown. We are requesting permission to do whatever it takes to deal with it, sir.”

“Carry on, General, let's see what you have for us.”

The plan General Taylor outlines calls for a capability to repel and destroy an unknown invading force arriving at an unknown time. Surprise would be of the essence given the unknown capabilities of the enemy.

“Still,” Taylor says, “There's not much an adversary can do against a Terawatt laser slagging its target to plasma.”

Within five years, he explains, highly-automated forts would be buried in the lunar far-side regolith, immune from asteroid-impact effects. Breakthrough Starshot lasers would be repurposed and re-sited off the Earth. Multi-Megaton missiles would lurk in stealth orbits around Mars and Venus and at their Lagrange points. Gigantic telescopes and late-stage radars would hide within the inner solar system.

This would be the last gasp of a dying Earth. All of its resources, those of all the countries of the world, would be deployed to keep the biosphere-recovery plan on track.

To give Plan Z the time it needs without interference.

“We'll have dedicated volunteers on the Moon. On Mars, if we can get them there. Bases provisioned with as many supplies as we can. Their task is simply this: to survive, to observe, to man the weapon systems. To develop the AIs to continue to serve after they die.

“We have five years, gentlemen. I assure you: we can do this.”

After the Impact

What can you do in more than a century of furious military preparation? Driven by AIs of exponentially-increasing capabilities with one imperative: Protect the Earth.

Build a solar system bristling with sensors and weapon systems - out into the Oort cloud.

Prepare retaliation: space-fabs turn out von Neumann machines - replicators with lethal competences; the survivors will breed to overwhelm any intruder. There are war-games in the asteroid belt.

Propelled on laser fire the AI strike force is an expanding shell, light years out. They share their threat assessments; wait to target the invaders.

The incoming bio-probe is detected and back-tracked. Layered defence systems move to readiness: titanic energies wait their moment of release.

The nearest AI attack-swarm is tasked and vectored on the bio-probe's source. A gargantuan death-cloud poised to exterminate Earth's killers.

---

Beneath the tunnelled debris of damp mulch and rot and new-grown ferns, the rat-things gorge on roots and flies and bugs. They are the first ones, the evolutionary generalists.

They chitter amongst themselves, tell simple stories, puzzle over strange lights in the sky. The lights which keep them safe.

The nascent civilisation of their new masters.