Superman #10/1981

In "Die Herren der Schwerkraft!", Superman and Batman join forces at the Pentagon to confront a crisis sparked by the captured Challengers Ace and Prof. Haley, whose failed mission has led to Dr. Charles Brock's forced creation of a gravity bomb capable of unraveling Earth's pull across North America. With gravity itself turned against them, the heroes must navigate a fortress of shifting forces to rescue Rocky Davis and stop the device before it’s too late. As the dust settles, the duo learns the Challengers are already gone—off to challenge the next unknown threat.