As one of Nasa’s elite crew of test pilots carrying out dummy runs for the proposed 1969 moon landing Mr Cernan had already strapped himself to the top of a Titan intercontinental ballistic missile in something resembling a galvanised dustbin – the mind-bogglingly low-tech Gemini capsule.
It was June 1966 and Mr Cernan, who died yesterday, was aboard Gemini 9. The three-day Nasa mission in Earth orbit was intended to rendezvous with an unmanned target vehicle but had failed.
Instead Mission Control instructed Mr Cernan to carry out a two-hour spacewalk.
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It's almost as if JFK reached out into the twenty-first century where we are today, grabbed hold of a decade of time, slipped it neatly into the (nineteen) sixties and seventies (and) called it Apollo.
This was only the second extra-vehicular activity (EVA) or spacewalk in human history. Nasa was basically making educated guesses and their mistakes almost cost Mr Cernan has life as the spacewalk went catastrophically wrong.
He later referred to the walk as “the spacewalk from hell” and described how the clumsy prototype pressurised spacesuit had led him to tumble and spin uncontrollably. Nasa had not yet realised the value of grab rails on the outside of spacecraft (they would subsequently be fitted routinely)
He vainly attempted to bring the Astronaut Manoeuvring Unit - an early predecessor to the jetpack style suits used on the Space Shuttle – but his spacesuit cooling system overheated, completely fogging his visor.
Gene Cernan: Last man to walk on the moon dies age 82
Exhausted, blind, and not a little terrified, with the help of crewmate Tom Stafford he managed to scramble his way back to the Gemini capsule.
The two astronauts splashed down in the Pacific hours later and were recovered by the USS Wasp aircraft carrier.
Mr Cernan’s courage and calmness under pressure was a trademark of his Nasa career which saw him cheat death on many occasions.
In 1971 just months before he commanded the Apollo 17 to the last ever Moon landing he was almost grounded by Nasa.
Mr Cernan had been flying a Bell 47G helicopter as part of his training for the Moon landing when he dipped too low and crashed into the Indian River at Cape Canaveral, nearly drowning.
He walked away with second degree burns to his face and was a whisker away from losing his place in the space capsule.
Memorably while on their way to the Moon the Apollo 17 crew took one of the most iconic photographs in space-program history, the full view of the Earth dubbed "The Blue Marble”.
Despite its fame, the photograph hasn't really been appreciated, Cernan said in 2007.
He added: "What is the real meaning of seeing this picture? I've always said, I've said for a long time, I still believe it, it's going to be – well it's almost 50 now, but 50 or a 100 years in the history of mankind before we look back and really understand the meaning of Apollo. Really understand what humankind had done when we left, when we truly left this planet, we're able to call another body in this universe our home. We did it way too early considering what we're doing now in space. It's almost as if JFK reached out into the twenty-first century where we are today, grabbed hold of a decade of time, slipped it neatly into the (nineteen) sixties and seventies (and) called it Apollo."
Mr Cernan died on Monday surrounded by family members according to US space agency Nasa, who added it was “saddened by the loss”.