"Okay, Sub," the Skipper announced finally, "We're not going to learn any more from out here."

He was probably right. The Skipper was an old hand, having served with distinction right the way through the War. He had been a wet-behind-the-ears Ensign yet to step onto a serving ship when hostilities had been declared, and was now Captain of the best damn heavy cruiser in the service, even if his crew consisted of just me.

He was a naturally taciturn man, keeping himself to himself while back at base and even managing to retain a degree of personal distance when cooped up in an acceleration suit for months at a time.

The ship had been moving closer to the asteroid for several hours, although not in any direct way and of course we had been doing our best to give the impression that we were not particularly interested in that specific asteroid: just a routine patrol, honest.

Our passive scans had been at maximum sensitivity the entire time we had been loitering, although there was no sign of radio emissions or energetic subatomic particles. This was not unusual: the Expansionists had had a lot of practice in concealing their presence buried beneath hundreds of metres of nickel-iron screening.

Under the maximum magnification of the optical and infrared telescopes, we had spotted various suggestions of what might just be airlocks and aerial arrays; if they were, they were carefully disguised so we could not be sure whether they were just natural formations. We have been deceived - or perhaps just deceived ourselves - on more than one occasion into thinking that unusual surface structures were actually signs of human activity.

There was at least one other anomaly: a deep dark pit which might be an impact crater, given the markings and ejecta surrounding it. But it looked unusual, untypical of the battered look that many of the larger asteroids have, although it did not seem to have any signs that it was a disguise for some kind of Expansionist military facility.

"Time to send in the Marines," the Captain added gruffly.

"Aye, Sir," I replied smartly, activating a sequence of commands I had prepared hours earlier.

Marines are not soldiers, or indeed human at all. They are smart machines, automata of a variety of sizes and capabilities. I'm told the name comes from an earlier fighting force, being regarded as very tough, ultimately expendable and with machine-like levels of dedication to duty.

The modern Marines are deployed as a dispersed cloud, the smallest no larger than a golf ball and being little more than a self-powered sensor platform, while the largest is the size of a small car and packing enough heavy weaponry to punch a hole through ten miles of solid asteroid.

The whole ensemble, large and small, was capable of flooding every part of even the most massive structures, seeking out military targets, or signs of life, or anything else which might be of interest. The various devices continuously communicate between themselves and then back to the analytics systems on the ship, leaving the genuinely human crew of two - just me and the Skipper - still safely cocooned, capable of accelerating out of danger, to report back to Earth Command if our foray elicited a hostile response, or pitch us into a full-scale attack position if that was required.

At my command, the ship swung about at maximum acceleration and headed almost directly for the anomalous rock which had attracted our earlier attentions. The background hum of the drives and the tick of the reactors become a deafening roar as the power outputs approached their design maxima. I could feel the pressure on my chest, squeezing the breath from my lungs, despite the acceleration suits and the inertia-nullification gravity fields.

No response of any kind was detectable from the target asteroid: no microwave or maser targeting scans, no interceptor missiles or railgun launches, no tell-tale blink of ranging lasers. I suddenly felt an overwhelming sense of disappointment; perhaps this was just a dead rock after all.

At the touch of a virtual button, I authorised the release of the Marines at the target as we passed by at our maximum velocity, continuing to execute a series of random course changes intended to evade any countermeasures which might still be launched in our direction.

As I watched, the assault force deployed in waves, the smaller components piggy-backing on the larger machines at first then peeling away as they drew closer, falling back while the larger of the modules targeted several of the points tentatively identified as disguised airlocks or entrances.

The lasers and railguns did their job, blasting away first the camouflage layers and then the mirror armour of the outer doors themselves. Fragments of asteroid rock and metal plates spun off in wild clouds, a few chunks intercepting the laser beams in a glittering spray which reduced each one to hot plasma. But there was still no response, no reactions from anything or anyone within.

A checkpoint was reached, giving the tactical command structure - me, as directed by the Skipper - a chance to make a key decision. I could hit the "hold" button, avoiding puncturing the final seals and releasing the air within. I let the moment come and go, letting the Marines blast open the inner doors in a spray of rapidly freezing gas. But not much: the air pressure and temperature within were already both desperately low, too low for easy survival of any human. I was already certain that there was nothing left alive inside the asteroid.

Part 2 Part 4