Dmitry Rogozin, director general of Russian state space corporation Roscosmos, sent a message of congratulations to NASA administrator Jim Bridenstine Saturday on the 50th anniversary of the moon landing.

"Fifty years ago Neil Armstrong, Buzz Aldrin and Michael Collins put themselves into the world's space exploration history books," Rogozin wrote.

They joined the crew of the great pioneers who dared to set off on a journey to the unknown in order to push the boundaries of the reachable world for humanity, he said.

"I do believe that our common goal is to be worthy of our great predecessors, to enrich their heritage and overcome all the difficulties on the Earth in order to continue the expansion of humanity into space," Rogozin said.

On July 20, 1969, the Apollo 11 spacecraft landed on the moon.

Hours later, Commander Armstrong descended a ladder onto the lunar surface and became the first man to complete what he famously described as "one small step for man, one giant leap for mankind."