Eyes That Watch

The Guardians of Space Keep Constant Vigil.
He, Sam Conway, was back from Mars now. Back from red, ferric deserts no Earthly boot had ever touched before. Back from bitter cold and aching dryness. Back from dazzling yellow hazes of dust and suspended ice crystals. No more need to wear oxygen armor in a thin, ozone-tainted atmosphere now. Back from solitude, and the endless fight to keep alive out there. Back from the enigma of Martian civilization's extinction, uncounted ages ago.... Back, back, back....
Home, now! From the window Sam Conway could see a row of maples, orange and golden in the autumn warmth. Kids were playing football in the street. Sam's oxy-hydrogen rocket ship, blued and battered and burnt, was suspended for all time from massive girders in the Smithsonian Institution. But even that was far away from Bryton, here. It should have been finished, now—the adventure. Sam Conway should have relaxed. Even Ellen Varney was beside him now. That should have helped. It did, a little. Yet only for moments at a time.
Those twenty months of exploration on another world, had become like a phantom in Sam's thoughts. Faded, distant, contrasting; yet starkly vivid too. Every hour had been a struggle. Extracting food substances from the tissues and juices of strange plants. Roasting native potassium chlorate in a small sun-furnace to extract oxygen from it, and compressing the precious gas into steel flasks. All this had been necessary, the dying Martian atmosphere contained only a low percentage of oxygen.
It had been a strange hand-to-mouth existence out there—a kind of game in which a fellow tried always to keep one small jump ahead of Death.
Hauling a crude little metal wagon, in which his supplies were packed, across the sand for miles and miles at a time, until his brain had reeled. Sleeping in a tiny airtight tent, when afield from his rocket.... Sam had never expected to survive those experiences. But he had, somehow; and it had done something to his soul—hardened it, and maybe killed part of it; and maybe beautified another part. For in spite of everything, those vast, ghostly solitudes of Mars were beautiful—