On Tomorrowland’s 1998 debut, Sequence of the Negative Space Changes (Kranky), Ann Arborites Nick Brackney and Steve Baker take a scrappy punk approach to space rock, imaginatively transforming limited resources–single-note electric guitar lines, simple keyboard figures–into meditative sheets of sound. A persistent darkness and drifting clouds of corrosive noise keep the beatless proceedings out of Tangerine Dream airspace: the isolation-tank synth surface of “Dustbot” is punctured by slowly intensifying electronic gurgles, while under the ethereal placidity of “Saturn” gently clashing harmonies create a subtle but inescapable tension. And on their latest release, a 12-inch single for the San Francisco label Darla, they actually stream in some murky, robotic beats. The duo’s performance this weekend will be flanked by a pair of Labradford side projects: front man Mark Nelson’s Pan-American and the local solo debut of bassist Robert Donne–about which, according to his reps at Kranky, he’s refused to divulge any details. Friday, 10 PM, Empty Bottle, 1035 N. Western; 773-276-3600. PETER MARGASAK