And it was at that moment, as I launched myself out into the abyss, that I knew that something was horribly wrong.

It is never completely silent inside a spacesuit; you can always hear the gentle hiss of oxygen, the faint whirr of fans and motors, the susurration of your own breathing—even, if you listen carefully enough, the rhythmic thump that is the pounding of your heart. These sounds reverberate through the suit, unable to escape into the surrounding void; they are the unnoticed background of life in space, for you are aware of them only when they change.

They had changed now; to them had been added a sound which I could not identify. It was an intermittent, muffled thudding, sometimes accompanied by a scraping noise, as of metal upon metal.

I froze instantly, holding my breath and trying to locate the alien sound with my ears. The meters on the control board gave no clues; all the needles were rock-steady on their scales, and there were none of the flickering red lights that would warn of impending disaster. That was some comfort, but not much. I had long ago learned to trust my instincts in such matters; their alarm signals were flashing now, telling me to return to the station before it was too late…

Even now, I do not like to recall those next few minutes, as panic slowly flooded into my mind like a rising tide, overwhelming the dams of reason and logic which every man must erect against the mystery of the universe. I knew then what it was like to face insanity; no other explanation fitted the facts.

For it was no longer possible to pretend that the noise disturbing me was that of some faulty mechanism. Though I was in utter isolation, far from any other human being or indeed any material object, I was not alone. The soundless void was bringing to my ears the faint but unmistakable stirrings of life.