I woke this morning with a heavy heart, realising that the sad news we received yesterday of Gene Cernan's death was not just a bad dream, but had really happened. A man whose youthful dream to fly had carried him beyond the limits of his imagination and the pull of gravity, to take him to the Moon and back.

Propelled by a gigantic Saturn V rocket and the hopes and ingenuity of a nation that had been challenged by their president to reach the Moon "before this decade is out", he was one of only 12 people ever to set foot on soil that was not of our mother Earth.

By any measure, it was an extraordinary collective achievement, one that will probably take another half a century to fully understand - although Cernan spent much of his later life doing a pretty good job reflecting upon and sharing his own part in the Apollo story.

Luckily for us, he was not just a gifted aviator and space pioneer, but also an eloquent and charismatic communicator, and those qualities, I feel, will be as much a part of his great legacy as the remarkable three days he spent living and working on the Moon.

As we all know, the first steps taken on the lunar surface in 1969 belonged to his good friend Neil Armstrong. Momentous steps that captivated the whole world, myself included, as we sat glued to our primitive TV sets. Three and a half years later, the steps taken by Gene Cernan may have seemed to a more jaded public at the time to be somehow less significant, but in terms of the science achieved, the sublime panoramic images captured, and the philosophical perspective obtained, the legacy of that final mission is immeasurable. As Cernan remarked at the time he prepared to depart from the Moon, this was not the end of space exploration by human beings, but the end of the beginning.

The Apollo 17 mission, like all lunar missions that had preceded it, had been designed and constructed as precisely as the Swiss watches the astronauts wore on their pressure-suited wrists. But it was Cernan and [lunar module pilot Harrison] Schmitt's more spontaneous, endearingly human actions that enthralled then, and endure today.

Don't make me out to be some kind of 'Mr Wonderful', because I'm really not Gene Cernan

The singing, the wise-cracking, and perhaps most memorably, writing the initials of his daughter in the lunar dust - a touching gesture from a man borne of the gung-ho, macho culture of military aviation.

Cernan was what people today might call an old-school hero; an all-American, alpha-alpha-male, competitive to the extreme, and on a personal mission to surpass the accomplishments of all his peers.

Perhaps that was the type of man NASA was looking for at that time. But while the lunar surface remains largely unchanged in 50 years, the speed of life and social evolution on Earth has moved on. We live in far more progressive times, and future missions to the Moon will inevitably and rightly comprise multinational crews of both men and women, funded perhaps by a mix of governments and global industries. Gene Cernan, despite being of his time, was pragmatic enough to accept and even endorse this, yet patriotic enough to still want an American on board, and preferably in the commander's seat.

During the filming of The Last Man on the Moon, Cernan spoke to me about this and many other space matters, offering his fascinating perspective, but as time passed and our relationship grew, we progressed to the more universal, sensitive and even fallible, human themes. The neglect of his family, the death of his closest friends, even some of the stupid things he did. He was self-confident enough, his shoulders broad enough to take these in his stride. Indeed, not long after we began the process of filming, he took me aside and said, "Don't make me out to be some kind of 'Mr Wonderful', because I'm really not".

Cernan had little regard for stories that were given the "Hollywood treatment", and had grown a little weary of countless people telling him how "wonderful" he was - even though in a large part it was true. He gave us licence to portray the "real deal" character he was, not just the stereotypical, silver-suited space hero, and because of that strength of character we are now left with a more enduring and honest legacy of the man.

The world has lost another pioneering astronaut, a Moonwalker, a real-deal space cowboy. But today as I write these words I feel I have lost a friend. He went from being just a name in a history book to someone I got to know as a real human being.

He was strong and yet endearingly fallible, tough when it mattered, but deeply sensitive. Serious, and funny. A regular guy who was also extraordinary. And part of something that was, quite literally, out of this world.

We shall miss him, but we can take some consolation that he lived a full and remarkable life and was hugely loved and admired. His name shall still be spoken of thousands of years from now. But Cernan would not be satisfied with the thought of human endeavour standing still. He never wanted to remain the last human to visit the Moon and threw down down the challenge to the next generation to "forge the destiny of tomorrow". Not just go the Moon and back, as John F Kennedy wished, but also to "do the other things" …

Let's not disappoint him.

Mark Craig is an independent director and producer. His most recent film is the critically acclaimed, multi-award-winning theatrical feature documentary, The Last Man on the Moon. His trilogy of British motor-racing biographies (Jackie Stewart / Graham Hill / Jim Clark) received an RTS nomination and a FOCAL award for best use of archive footage, while his 2007 short film Talk to Me won a Grierson Award for innovation.

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.