Galaxy's End

From the back cover of the Ace first edition: Daniel Kitajima was a creature of mind and machine. His artificial limbs were endowed with superhuman strength, his perceptual abilities enhanced with telescopic vision, radar and infrared. With proper care, he would live forever - except for one grim and inevitable fact... The solar system was about to be destroyed. The sun was heating up, scorching Earth's deserts and transforming its polar icefields into quagmires. The entire galaxy was in danger. And nothing human could halt the oncoming disaster. But Daniel Kitajima is not exactly human...