The gages still showed their last maximums. Skin 793 Kelvin, Cabin 144 Fahrenheit, Gravs 3.2. All of them hit almost a year ago, when they'd been ace-ing past the sun. Grunfeld's gaze edged back to the five bulbous pressure suits, once more rigidly upright in their braced racks, that they'd been wearing during that stretch of acceleration inside the orbit of Mercury. He started. For a moment he'd thought he saw the dark-circled eyes of the captain peering between two of the bulging black suits. Nerves! The captain had to be in his cabin, readying alternate piloting programs for Copperhead. Suddenly Grunfeld jerked his face back toward the spaceshield--so violently that his body began very slowly to spin in the opposite direction. This time he'd thought he saw the Enemy's green flashing near the margin of the planet--bright green, viridian, far vivider than that of Uranus herself. He drew himself to the telescope and feverishly studied the area. Nothing at all. Nerves again. If the Enemy were much nearer than a light-minute, Jackson would esp it and give warning. The next star was still three minutes from rim contact. Grunfeld's mind retreated to the circumstances that had brought _Prospero_ (then only _Mercury One_) out here. II When the First Interstellar War erupted, the pioneer fleets of Earth's nations had barely pushed their explorations beyond the orbit of Saturn. Except for the vessels of the International Meteor Guard, spaceflight was still a military enterprise of America, Russia, England and the other mega-powers. During the first months the advantage lay wholly with the slim black cruisers of the Enemy, who had an antigravity which allowed them to hover near planets without going into orbit; and a frightening degree of control over light itself. Indeed, their principal weapon was a tight beam of visible light, a dense photonic stiletto with an effective range of several Jupiter-diameters in vacuum. They also used visible light, in the green band, for communication as men use radio, sometimes broadcasting it and sometimes beaming it loosely in strange abstract pictures that seemed part of their language. Their gravity-immune ships moved by reaction to photonic jets the tightness of which rendered them invisible except near the sun, where they tended to ionize electronically dirty volumes of space. It was probably this effective invisibility, based on light-control, which allowed them to penetrate the Solar System as deep as Earth's orbit undetected, rather than any power of travel in time or sub-space, as was first assumed. Earthmen could only guess at the physical appearance of the Enemy, since no prisoners were taken on either side. Despite his impressive maneuverability and armament, the Enemy was oddly timid about attacking live planets. He showed no fear of the big gas planets, in fact hovering very close to their turgid surfaces, as if having some way of fueling from them.