US astronaut Neil Armstrong's Apollo 11 comrades Buzz Aldrin and Michael Collins paid tribute to their late commander's talent and accomplishments, noting that they would miss him.
"Whenever I look at the moon, it reminds me of the moment over four decades ago when I realised that even though we were farther away from Earth than two humans had ever been, we were not alone," Aldrin said in a statement.
"Virtually the entire world took that memorable journey with us. I know I am joined by millions of others in mourning the passing of a true American hero and the best pilot I ever knew."
Armstrong's family announced this morning that the space pioneer had died of complications following cardiovascular surgery. He was 82.
Aldrin said he had hoped that he, Armstrong and Collins would have met up in 2019 for celebrations marking the 50th anniversary of Apollo 11.
"Regrettably, this is not to be. Neil will most certainly be there with us in spirit," he added.
"I will miss my friend Neil as I know our fellow citizens and people around the world will miss this foremost aviation and space pioneer."
Collins, in a statement released by a Nasa spokesman, said of Armstrong: "He was the best, and I will miss him terribly."
John Glenn, the first American to orbit Earth, said Armstrong "truly was a person who dared greatly."
Speaking to CNN, he recalled Armstrong's legendary humility.
"He didn't feel that he should be out huckstering himself or anything like that and he just remained true to the principles he grew up with," said Glenn, a former Ohio senator.
"He was a humble person, and that's the way he remained after his lunar flight, as well as before."