Talk about 90-day wonders! America's Viking I landing craft, parked on Mars's Plains of Gold, had only a 90-day guarantee, but it kept sending back weather reports and pictures for years after its arrival in 1976. Last November this outpost of Earth stopped transmitting. Last Saturday the final scheduled attempt to rouse it failed. Dead batteries.
''The rest is silence,'' as Shakespeare said. But we can't think of Viking as a Hamlet full of tragedy, more as a Leif Ericson full of beans.