"The pattern of spheres certainly suggests the Sun-tappers to me," said Burl. Haines murmured his agreement. Lockhart's voice came on the phones. "We've decided it's one of the Sun-tapper ships. We're not going to wait to make sure. Before we left Earth, I can now inform you, I received a directive from the President to regard the builders of these Sun-tap stations as active enemies. My orders are that we are not to attempt to undertake peaceful contact, but are to treat them on sight as armed foes in the field. To do otherwise is to risk Earth's last active defense--this ship. "I think I don't have to argue this further, considering our recent experiences." His voice hesitated, then rang out firmly, "Haines, you can commence firing at will!" Haines clicked his tongue and reached for one of the shells. "Okay, Burl, aim at her direct. This one's got a proximity nose that'll beam at her and drive itself where ever she ducks." He slid the rocket shell into the launcher, Burl sighted, and then Haines pressed the trigger. There was a whoosh of fire and a flare from the launcher's nose. A minute spark winged into the darkness toward the spot, still many miles away, where the strange ship hung. They watched with bated breath. Suddenly there was a flash of light from the other ship--a vivid lightning bolt which leaped out and flared up briefly in space. Then darkness again. "They fired a burst of energy at us. It hit the rocket shell instead," said Haines. "Well, now we know. They use bolts of pure energy--something like the one they fired at Boulton." He fitted another shell into the launcher, and fired again. Again a spark winged its way, and the bolt of energy burst out to detonate the shell. Burl whistled. "How did they spot it so fast?" he asked. "I don't think they did. They're firing at us--the rocket shell only happened to be between," snapped Haines. "Ferrati," he called into his mike, "fire a shrapnel shell at them when I say the word. Advise me when ready!" Ferrati's voice snapped back. "Right you are, sir. Here it is now, one minute--okay, on target!" While Ferrati and Boulton were readying their shot from the lower cargo port near the tail of the ship, Haines and Burl had been fitting the largest of their shells into their own launcher. They aimed it carefully at the front-most sphere of the enemy. "Ferrati, fire!" cried Haines, and then slowly counted to five and pressed the stud of his own launcher. There was a momentary flicker as Ferrati's rocket shell raced forth below. Then, after a definite time lapse, the exhaust of Haines' heavy shell appeared. "The shrapnel shell is segmented and doesn't have a proximity guide," Haines explained. "As soon as it's on its way, the nose comes apart into a dozen small shells, each with a standard explosive charge. The shell we used has an atomic bomb warhead and is on proximity guide. It'll chase that ship to the ends of the system if they don't blast it first."