Season ten of the series premiered on January 19, 2011. Many changes were introduced this season, from the format to the personnel of the show. Jennifer Lopez and Steven Tyler joined Randy Jackson as judges following the departures of Simon Cowell (who left to launch the U.S. version of The X Factor), Kara DioGuardi (whose contract was not renewed) and Ellen DeGeneres, while Nigel Lythgoe returned as executive producer. Jimmy Iovine, chairman of the Interscope Geffen A&M label group, the new partner of American Idol, acted as the in-house mentor in place of weekly guest mentors, although in later episodes special guest mentors such as Beyoncé, will.i.am and Lady Gaga were brought in.

Answer this question, if possible (if impossible, reply "unanswerable"): In which season of American Idol did Steven Tyler and Jennifer Lopez become judges?
ten