John Glenn, who became one of the 20th century's greatest heroes as the first American to orbit Earth and later as the world's oldest astronaut, died on Thursday at age of 95.

Glenn was the last surviving member of NASA's original seven "Right Stuff" Mercury programme astronauts.

"John Glenn is, and always will be, Ohio's ultimate hometown hero, and his passing today is an occasion for all of us to grieve," Ohio Governor John Kasich said in a statement.

Glenn was credited with reviving US pride after the Soviet Union's early domination of manned space exploration. His three laps around the world in the Friendship 7 capsule on February 20, 1962, forged a powerful link between the former fighter pilot and the Kennedy-era quest to explore outer space as a "New Frontier".

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As the third of seven astronauts in NASA's solo-flight Mercury programme to venture into space, Glenn became more of a media fixture than any of the others and was known for his composure and willingness to promote Mercury.

Glenn's astronaut career, as well as his record as a fighter pilot in World War II and the Korean War, helped to propel him to the US Senate in 1974, where he represented his home state of Ohio for 24 years as a moderate Democrat.

But his star was dimmed somewhat by a Senate investigation of several senators on whether special favours were done for a major campaign contributor. He was cleared of wrongdoing.

Glenn's entry into history came in early 1961 when fellow astronaut Scott Carpenter bade him "Godspeed, John Glenn" just before he was rocketed into space for a record-breaking trip that would last just under five hours.

"Zero-G [gravity] and I feel fine," was Glenn's succinct assessment of weightlessness several minutes into his mission. "Oh, and that view is tremendous."

After splashdown and recovery in the Atlantic Ocean, Glenn was treated as a hero, addressing a joint session of Congress and being feted in a New York ticker-tape parade.

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His experiences as a pioneer astronaut were chronicled in the book and movie The Right Stuff, along with those of the other Mercury pilots. The book's author, Tom Wolfe, called Glenn "the last true national hero America has ever had".

"I don't think of myself that way," Glenn told The New York Times in 2012 to mark the 50th anniversary of his flight. "I get up each day and have the same problems others have at my age. As far as trying to analyse all the attention I received, I will leave that to others."

Glenn's historic flight made him a favourite of President John Kennedy and his brother Robert, who encouraged him to launch a political career that finally took off after a period as a businessman made him a millionaire.

Source: Reuters news agency