When popular musicians return to the limelight after a long absence, they arrive with different ambitions. Some remain shamelessly stuck in the past, peddling nostalgia for the artists they used to be. Some struggle self-consciously against anachronism, trying to convince the world they have something new to say–when in fact they don’t. But the best of the lot come back refreshed, full of fire and new wisdom.Two such artists have reappeared in recent months: folksinger Odetta and punk veteran Joe Strummer. From wholly different worlds–she from Birmingham, Alabama, via Los Angeles, he from the north of Scotland via London–they have surfaced with vibrant new albums that transcend the “comeback” label.Odetta hasn’t made a full studio recording in more than a decade. But her legend is large, thanks to her supporting role in the folk boom and social foment of the ’60s. Bob Dylan and Janis Joplin, both ardent admirers, studied Odetta’s repertoire and singing style early in their careers. Odetta was out front in the civil rights movement, marching with Martin Luther King Jr. and performing before President John F. Kennedy on national TV. Her lasting influence can be heard today in artists as diverse as Jewel, Nanci Griffith, and Cassandra Wilson.Rather than settling into her autumn years as one of the folk scene’s elder stateswomen, Odetta is back with a passion. Blues Everywhere I Go is the name of her new release as well as the first phrase out of her mouth, and she delivers on the theme with songs about joblessness, lovelessness, disease, oppression, and death. But in Odetta’s hands, the music isn’t as bleak as those subjects suggest: Her nuanced, crisp phrasing carries a dignity that pulls her through the hard times, turning burdens into affirmations.Odetta’s song choices, many culled from the repertoires of pioneer blueswomen, carry an unmistakable political weight. “Rich Man Blues” urges the world’s fat cats to “give the poor man a chance, help stop these hard, hard times.” “W.P.A. Blues” is a reminder that the nation’s highway-building frenzy often meant condemnation notices for the underclass. And “TB Blues” gives voice to the alienation of disease victims; it could just as well describe HIV.On two beautiful ballads, “Please Send Me Someone to Love” and “Oh Papa,” the singer’s only accompaniment is Dr. John’s supple, earthy piano. Other songs feature a fuller band, but the focus always returns to Odetta’s voice: pure, proud, and finely expressive.Joe Strummer hasn’t got half the vocal chops of Odetta, but no matter. The burr-voiced former Clash member and his Mescaleros band are showing that a punk rocker can age gracefully while remaining vital. Strummer’s new album, Rock Art and the X-Ray Style, is a fresh blast of creativity from a bloke who’d largely gone AWOL from the music scene.In the Clash, Strummer was a hybrid-hungry innovator, melding punk rock’s explosive energy and do-it-yourself ethos with a global consciousness. On the new CD, he makes clear from the outset that he’s still mixing things up. “Tony Adams” opens with an electronic buzz, a ska beat, and a droning spaghetti-Western guitar note before unfolding into a languid, half-rapped jam.From there the album veers all over the map. “Sandpaper Blues” and “Yalla Yalla” are uplifting, mantra-driven world-music numbers. The guitar- and beat-heavy “Techno D-Day,” which is about cops shutting down a rave in Cornwall, is a late-’90s version of the Clash’s “White Riot.” “Nitcomb” is a startlingly tender love song using an unlikely metaphor, and “Road to Rock ‘n’ Roll” is a reflective ballad with an instantly classic opening line: “On the road to rock and roll, there’s a lot of wreckage in the ravine.”This is no Sandinista!–the Clash’s 1980 sociopolitical opus. Strummer’s defiant political conscience, which once extended to wearing armbands for his favorite causes, surfaces only on “Forbidden City,” where he addresses the Tiananmen Square massacre, and “Techno D-Day,” where he stands up for freedom to rave. Instead, Strummer treads more personal territory here. He is clearly taking his own advice to “live in this world,” as he sings on “Diggin’ the New,” and his drive to stay in the game is inspiring. Another just-released album, From Here to Eternity: The Clash Live, is bracing and welcome, but it’s an already sepia-toned snapshot from yesteryear. Rock Art and the X-Ray Style is a Polaroid taken just yesterday, and its colors are still emerging.