Richard Ellis paces impatiently back and forth across a small room lined with computer terminals, trying to contain his mounting frustration. The British-born astronomer, now at Caltech, has been granted a single precious night to use one of the twin Keck telescopes, among the most powerful in the world. Last night he and his observing partner, a graduate student named Dan Stark, flew 3,000 miles, from Southern California to Hawaii, where the Kecks are located. And during most of the afternoon and early evening today, they've made their final plans for the "run," as astronomers call a night of peering into the heavens. ...