After 84 days aboard the Russian space station Mir-- and a bracing diet of canned Russian perch -- American astronaut Norman Thagard has broken the U.S. space endurance record set by three Skylab astronauts in 1974. Now, he's ready for the green hills of Earth. "I miss my family," said Thagard, who became the first American to be launched on a Russian rocket Mar. 14. "I've got three sons and a wife and two cats, and I like them all and I miss them." Unfortunately, he's got another month to go. One Skylab astronaut, Edward Gibson, today radioed up some moral support: "Norm, keep on trucking."