They came without warning.

After so many years of finding nothing, the scientists had given up hope of ever finding life on Mars. Despite all of the probes, all of the rovers, Mars seemed destined to remain a dead planet.

Spirit had been silent for years and it seemed that Opportunity would so follow on in its sister’s wake. Curiosity soldiered onward, drilling and lasering its way across the dusty ground.

Each week it seemed, there was some new discovery; compounds from meteorites that revealed how the early solar system had come to be, ancient rocks that could only have been shaped by flowing water, deep in the red planet’s shadowed path.

But never the Holy Grail, the one thing everyone wished for, even if they could no long admit to it in public.

Never signs of life.

Never the slightest hint that Earth may not have been unique in the universe.

It took less than a day.

That’s all the warning we could have had, even if we had known exactly what was happening, right from the very beginning.

There was a sudden massive storm over Cydonia–the region of Mars made famous decades earlier with the image of a face in the stone where no face should have been–where no face could have been.

The dust was enough to block satellite observations for a matter of hours. Nothing too strange in that alone–dust storms on Mars could last months, given the pepper conditions–but when the dust cleared, there were the holes. Four of them, each perfectly round and black as darkest night, cutting deep into the planet’s core. Arranged in a perfect square, they bordered what had once been though a pyramid, although to the trained the it was nothing more than shadows and stone.

It was only hours later that the projectiles were discovered. Four of them, by then already halfway to Earth. They were tiny really, no more than a few hundred cubic meters each. It was only by the grace of the meteor scares years before that the telescopes capable of tracking them existed. Even then, it was hard to keep them in focus.

They were just moving too fast.

The best and brightest the world had to offer worked through night and day, trying to determine what could be done. One by one though, they each came to the same conclusion.

Nothing.

There was nothing we could do but wait.

The first struck in Siberia, thousands of miles from civilization. The devastation was catastrophic, although the death toll was minimal. It struck with the force of a nuclear warhead, thawing what was left of the permafrost and leveling the forests for miles around.

Seventy four minutes later, the second struck. The blow came to Mongolia, obliterating the landscape far more ruthlessly than any weapon mankind had dared to use. Thousands died. Tens of thousands. Hundreds.

Seventy four minutes later, the third struck the Indian Ocean, sinking deep into the sea floor between India and Africa. There was a geyser of steam and a tidal wave the better part of a kilometer high. There was little enough warning for those living by the coasts, but it wouldn’t have mattered. The waves rushed onward, only growing taller still as the neared land.

Millions died. Countless lives were torn apart.

The forth and final strike occurred yet another seventy four minutes later.

It struck squarely in the heart of Johannesburg. Four million died in a heartbeat and the fires of destruction were only beginning to radiate outward.

It was only later, far later, that we realized that all of our probes, all of our satellites in orbit around Mars had gone silent.

One moment, they were sending telemetry as normal; the next, nothing.

There was a brief burst of data at the end, a short transmission in audio. It was sent from every probe, in every language–even those on the brink of extinction. Every language still spoken on the face of the Earth.

The message was simple.

“DO NOT RETURN TO MARS.”

Bolstered by the knowledge that we were not alone–furthered even more by the notion that ET was out to get us–humanity exploded from its cradle.

In the span of a century, mankind grew up. Technology was advancing left and right, cheap energy and materials that we could hardly have dreamed of paving the way to the stars.

The Moon was first. Then the moons of Jupiter and Saturn. Some enterprising entrepreneurs somehow even managed to plant a stable environment onto Venus’ fiery bosom.

But never Mars.

Oh, there where those who tried.

The first satellites to return were launched within the decade. None remained active for more than a minute.

Then there were probes, sent in electromagnetically hardened shells designed to withstand the worst either man or nature could dish out.

Not one reported even landing on the surface. The most powerful telescopes mankind could muster–built on the dark side of the moon itself–showed little more than fiery impact craters. The probes should have been able to survive that.

But somehow they hadn’t.

The worst was the single manned mission.

Some say it was the Chinese, others the Russians. A few even said it was American, although of course the President denied it.

Whoever they were, they reasoned that a manned mission, flying a flag of peace, might just succeed where automated tools had failed.

For the first time in decades, one of the four original silos opened once again.

The debris rained down towards the surface of Mars, fragments so small that even that minuscule atmosphere was enough to incinerate them.

Two hundred years passed and the human family grew. Once again, there was talk about reclaiming Mars, about conquering the one frontier truly left within our own solar system.

Plans were made. What little autonomy the few remaining nation states has managed to hold onto faded before the collective will of humanity.

The solar system was ours. We would have Mars.

The arsenals of the world were gathered. Some–many–worried that even that would not be enough. That the product of centuries of paranoia would only serve to provoke another strike from our silent foes.

But the collective ruled. The weapons were gathered.

A secret base was built on Deimos. Few had ventured so far in centuries of expansion, feeling the risk of retribution was too high.

But Deimos was not Mars. The preparations proceeded with issue.

Three hundred years to the hour from the moment the first strike had been launched against Earth, the counter strike began.

There were a thousand warheads, some with the theoretical capacity to crack a planet’s crust.

It likely wouldn’t be possible to live on Mars for many years after the strike, but even that seemed a price worth paying. The thinking went that if we couldn’t have it, well then neither could they.

Just like that, it was over. A new crater decorated the surface of Mars, blackened by gigatons of nuclear might, cutting a swath to rival even Olympus Mons.

Nothing was left of the face on Mars, no sign was seen of those four dark circles in their perfect square.

The first satellite in orbit came from Deimos. It remained active for hour after hour, transmitting pictures of a storm to end all storms whipping around the girth of an entire world. It would be years, decades, before it would be safe to send a living souls down to the surface.

A decade later and the storm still raged. Radiation levels the planet over would have cooked any man to so much as enter the atmosphere.

But man was growing yet again, reaching beyond the frail limits of the skin and bones, augmenting themselves with steel and silicon. The augments–as they were called–could survive the radiation. They could survive the storm.

The first team to the surface landed near the center of the crater, scant kilometers from what was rapidly becoming a sea of dust–an ocean of particles so fine they flowed like water.

Deep in that ocean, scans indicated something irregular. Something solid. Four cylinders leading down from what had been the surface, snapped off decades before.

Something remained.

The augments swam down through the dust and deep into the cylinders, down kilometers beneath the surface of the planet. Even their transmitters couldn’t hope to punch through that, so for a few hours more, the whole of humanity waited with baited breath.

When they once again surfaced, a hundred billion sighed as one. The stories they told–of a cavern large enough to hold an entire city, of technology so strange it may well have been magic–fell to the wayside of one simple truth: they were alive. They were alone.

In the decades that followed, no one could determine for certain if there has been anyone–anything–present for that first strike, oh so many years ago. It could all have been automated, like so much of the alien city seemed to be.

There were records that whoever they had been, they had come from far away. They had come many millions of years ago, finding one blue world teeming with life. They had set up an outpost, waiting and watching from the planet next door.

And then they had gone. All but a skeleton force, moving on to whatever other worlds there were, a hundred billion homes among the stars.

They had always meant to return. That much was clear.

And one thing became absolutely certain as the augments returned again and again to the bowels of the ruined city.

They knew.

The aliens knew.

A distress beacon had sounded off the instant our warheads had detonated. Traveling at the speed of light, spreading outward in all directions, tens of star systems had already heard its call. Hundreds. Soon it would be thousands.

If those that had built this place were still out there, they would hear it. It was only a matter of time.

They would hear it.

And they would come.

In the end, we became the observers. Waiting, watching, vigilant against a return that may never come–against a return that we hoped would never come.

We become the observers.