Blockade: Lepso (Perry Rhodan #101)

The series begins with the first manned moon landing (in 1971) led by U.S. Space Force Major Perry Rhodan. However, things do not go as planned and the astronauts discover a stranded alien spaceship from a star system called Arkon and its crew who need medical help. The realization that mankind is not alone in space and access to the aliens' advanced technology lead to the (not entirely trouble-free) political unification of Earth under the eponymous hero-protagonist Rhodan