Astronaut: The word itself comes freighted with peril and romance.

Star-sailor, astral explorer, navigator of the heavens. While the popularity of space exploration has waxed and waned, the grip of the astronaut on the public imagination has hardly wavered over the past half-century.

In his 1979 book The Right Stuff, Tom Wolfe identified the quality peculiar to astronauts – a unique substance, combining grit, phlegm and a certain understated style. The astronaut, Wolfe wrote, is comparable to the single combat champion of classical times, the lone warrior sent out to fight to the death if necessary on behalf of his comrades.

Soldier-scientists, swashbuckling geeks, astronauts straddle different worlds, in many senses. In the glory days of space exploration, astronauts were drawn from the military, cogs in a vast machine, but they were also recognisable individuals. They were celebrities, but seldom extracted personal glory from their fame. They were prepared to brave death, but in a way that was rigorously cautious.

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The astronaut and cosmonaut were political symbols, warriors in the Cold War with huge propaganda value. John Glenn, the first American to orbit Earth, was pictured waterskiing with John F. Kennedy; Yuri Gagarin became the “Columbus of the Cosmos” in Soviet hagiography, and made to say things that he never uttered in reality. Gagarin is reputed to have said: “I don’t see any God up here,” on reaching the heavens. He never said it, according to verbatim transcripts, but it suited atheist Soviet propaganda that he should have.

While they were products of the Cold War, astronauts somehow floated above politics in the popular imagination. The greater purpose blunted the ideological point-scoring by both sides. “We go into space,” Kennedy said, “because, whatever mankind must undertake, free men must fully share.” The pilots of space offered a pure form of intellectual fulfilment, the answer to riddles as old as humanity. In the words of the 17th-century astronomer Johannes Kepler: “The diversity of the phenomena of Nature is so great, and the treasures hidden in the heavens so rich, precisely in order that the human mind shall never be lacking in fresh nourishment.”

Astronauts were extraordinary, but also normal. Of none was this more true than Helen Sharman, the first Briton in space. The Sheffield-born Sharman was working at Mars, the confectionery company, working on chocolate flavouring, when she heard a radio advertisement inviting applicants for a place on the Soviet Soyuz TM-12 rocket, heading to the Mir space station in 1991. She was selected from 13,000 candidates. She still does not know why. “My story goes to show that there is a lot of luck involved in life,” she once said.

That understatement was typical of the astronaut. They were scientists and pilots. They were not poets, and only a few, most notably Michael Collins, the command module pilot on Apollo 11, could rise to lyricism when describing where they had been.

Even the most famous space phrase of all – “That’s one small step for man, one giant leap for mankind” – was blunt, and not quite what Neil Armstrong had intended to say, which was “one small step for a man”.

Astronauts, on the whole, don’t do small talk. Some did almost no talk at all. The three crew of Apollo 11 were famously laconic, exchanging barely a word beyond what was necessary. They were, it was said, “the quietest crew in manned space flight history”.

Only a few happily embraced the razz-matazz that awaited back on Earth. Most wore fame uncomfortably, and expressed wry amusement at the more extreme manifestation of celebrity, such as the sculpture of Armstrong created by the Ohio Dairymen’s Association out of 900lb of butter.

The reluctance was sometimes feigned, as much a part of the uniform as a space suit. “I must admit,” the late Alan Shephard, the second person and the first American astronaut in space, said, “maybe I am a piece of history after all.”

Space explorers required many of the same attributes as their predecessors on Earth: physical strength, fast thinking, and the ability to withstand mind-crushing boredom and repeated disappointment. The great astronauts, like the greatest explorers, combined drive and patience in equal quantities.

On the other hand, the demands of space travel were new. Explorers in the past were not tracked by live television, and required to be performers as well as scientists and adventurers. It took a peculiar sort of person to be able to share a tiny metal cubicle, alongside thousands of gallons of explosive fuel, surrounded by darkness, without going mad.

Along with the right stuff came other, more difficult stuff. Buzz Aldrin had a long, but ultimately successful battle with alcohol and depression.

More recently, Lisa Nowak, who flew aboard the Space Shuttle last year, was arrested and charged with the attempted kidnapping of the girlfriend of a fellow astronaut.

But more astonishing than the examples of human frailty is the fact that so few of the 460 astronauts cracked, or even bent, under the strain. The combination of mental and physical resilience may be best illustrated by something that happened to Armstrong, commander of the 1969 Moon landing, a decade after his return to Earth.

While working on his farm, the former astronaut caught his wedding ring in the wheel of a grain truck and tore off his finger. Armstrong picked up the finger, packed it in ice, climbed into his car and drove himself to the local hospital, where micro-surgeons reattached the digit. The press went into hyperdrive; Armstrong thought it no big deal.

If that recalls earlier explorers patching themselves up and trudging on, it is no accident.

In 1913, this newspaper carried a recruiting appeal from Sir Ernest Shackleton, who was planning his expedition to the Antarctic.

The words of The Times advert, now nearly a century old, precisely frame the character of the astronaut, seafarer of the modern age: “Men wanted for hazardous journey. Small wages, bitter cold, long months of complete darkness, safe return doubtful. Honour and recognition in case of success.”