Jefferson Starship is an alternative rock group. That is, they give an audience a taster's choice of stances -- the psychedelic origins, the sci-fi middle ground and the metallic dead end. Ironically, as they moved from Airplane to Starship to the earthbound and mundane merry-go-round of commercial consideration, they've become increasingly less imaginative.

Which didn't seem to make much difference to Starship fans at the Merriweather Post Pavilion last night. Perhaps it's the privilege of a seminal rock band to only look forward. In any case, Starship refused to allow the rain on their charade. Like an oscilloscope, the band powered its frequent high moments -- Grace Slick's raunchy and riveting vocal gymnastics, in particular -- with the same exhilarating abandon they brought to the equally frequent low moments, highlighted by Aynsley Dunbar's meandering, pit-stop drum solo.

Slick sounded just fine. Her enforced separation from the band seems to have helped her recover the hard vocal edge and orneriness that were always the band's distinguishing characteristic; she's a welcome diversion to Mickey Thomas' tight-belt histrionics. Some of the older songs, particularly the opening "Somebody to Love," were surprisingly ragged, while many of the newer songs suffered from uninspired writing. And with Bad Company off the road, having "Jane" and Mistreater" played back-to-back satisfied the metallic lust.Still, Starship in flight on the classic "White Rabbit" can soar to majestic heights . . . just as Skylab once did.