Martin had been a surprise choice for the commission.

It was the Spring of 1977 and two Interstellar Mariners were to be sent hurtling into deep space. Glass was to provide weekly "sonologues" of their progress, audio diarist for a pair of mute mechanical adventurers.

Delivered with a near fanatical diligence over the course of nearly three decades, these stuttering musical biographies would soon bewilder those who had first asked for them.

Martin's work, they judged, had begun to plot its own eccentric orbit, charting more than just the ships' material progress, but rather their imagined psychogeography ("What will they say about me?" "I will never conserve my instruments" "Nobody has gone further").

With his sonic dispatches increasingly ignored and unheard, all funding for the project swiftly fell to dust.

The very best of these scores, chosen from a vast compendium of source material, are now assembled here for the first time. Their muses, two arthritic spacecrafts now nearly half a century old, limp on through deep space, forever onwards and onwards forever...