Several stories featured characters traveling back in time to visit Krypton before its destruction; one example is the 1960 story "Superman's Return to Krypton", in which Superman is swept back in time to Krypton some years before its destruction. Powerless, he spends some time on the planet, where he meets his future parents-to-be and falls in love with a Kryptonian actress named Lyla Lerrol. A "Superman" "imaginary story" entitled "What If Krypton Had Not Exploded?" (reprinted in the trade paperback "The Greatest Superman Stories Ever Told") gave more insight into Krypton's society. This era also established that the Guardians of the Universe, the administrators of the interstellar police force, the Green Lantern Corps, were themselves aware of Krypton's pending destruction and assigned Green Lantern Tomar-Re to avert it, but he was ultimately unsuccessful in his attempt.