Here’s some happy news: Boston Rock Opera, which used to stage rock operas, album and artist tribute shows, and evenings of conceptual rock performance, is returning after a long period of dormancy. Producer/director Eleanor Ramsay has confirmed that BRO is coming back Aug. 6 and 7 with “Stardust to Blackstar: The Lives of David Bowie,’’ which will be staged at Once in Somerville. Founded in 1993, Boston Rock Opera is best known for its cult presentation of “Jesus Christ Superstar,’’ which featured Extreme singer Gary Cherone as Judas, and its theatrical premieres of Ray Davies’s “Preservation’’ and the Pretty Things’s “S.F. Sorrow.’’