Apollo 14 Moon shot: Alan Shepard 'told he was too old'
When Apollo 14 landed on the Moon, 40 years ago this week, mission commander Alan Shepard was the oldest astronaut to have flown in space.
In order to fulfil his dream of walking on the Moon, 47-year-old Shepard had to fend off criticism of his age and overcome a health condition which had dogged his career.
While age poses no particular barrier to being an astronaut today, in the early days of human space flight, officials were unsure what influence the ageing process might have on performance during a mission.
Shepard died in 1998 of leukaemia. But in a 1991 interview, he recalled the questions over his age: "We got all kinds of flak from the guys. In the first place, I hadn't flown anything since 1961, and here it was 10 years later, and the two guys with me had not flown before at all, so they called us the three rookies.
"We had to put up with that. And then the fact that everybody said: 'That old man shouldn't be up there on the Moon.' As if it wasn't enough of a challenge as it was, but that was part of the make-up of all those guys. They are still a pretty competitive group."
Shepard had been one of the original seven astronauts recruited by Nasa in the late 1950s - at the beginning of the space race with the Soviet Union. These fiercely competitive former military test pilots were known as the Mercury Seven.
In 1961, Shepard was picked out from the other "fighter jocks" to become the first American in space - after the Soviets shocked the world by boosting Yuri Gagarin into orbit.
According to Reginald Turnill, the BBC's former aerospace correspondent, Shepard was "tall, thin and ambitious", as well as somewhat acerbic in person.
"All the Mercury Seven astronauts were [ambitious] because thousands of people applied to be Nasa astronauts," says Mr Turnill. "Shepard was probably the most pushy of the seven."
According to Turnill, Shepard had initially harboured ambitions to become the first man on the Moon - an accolade that eventually went to Neil Armstrong.
But in the early 1960s, Alan Shepard had been diagnosed with a rare condition of the inner ear called Meniere's disease. This disorder, caused when fluid pressure builds up in the inner ear, can affect both hearing and balance, resulting in disorientation, dizziness and nausea.
Consequently, he was disqualified from space flight and only allowed to fly Nasa's T-38 training aircraft with a second qualified pilot on board.
As Apollo 7 astronaut Walt Cunningham explains in his memoirs The All American Boys: "For a man of Al's temperament, ambition and ability, this kind of dependence had to be a helluva blow to his pride."
Shepard had been compensated with a senior desk job in Nasa's astronaut corps, but Cunningham says that, as crew after crew took the flight to the Moon, "Al must have felt like the boy left to guard the sheep while the hunters went after the fox."
In 1969, he checked himself into a Los Angeles hotel under a pseudonym to undergo a new and, at the time, risky operation to correct his inner ear condition. The surgeon successfully implanted a small tube in his inner ear to drain the fluid away.
"I finally found a gent who corrected my ear problem surgically, and after Nasa looked at me for perhaps a year, they decided that I was well enough to fly again," Shepard explained in 1991.
Shepard kept the surgery from his peers, but they soon noticed he was flying Nasa's T-38 plane by himself.
The first American in space began training again, with his sights set on commanding the Apollo 13 mission. But navigating Nasa politics was going to be vital if he was ever going to walk on the Moon.
Alan Shepard embarked on an internal campaign for a place on the prime crew. Luckily he was backed in his endeavour by longtime friend Deke Slayton - another of the original Mercury Seven - who was responsible for Apollo crew assignments at the time.
According to Walt Cunningham, there was a sentimental wave of support for Shepard, but some were resentful of what Cunningham calls the astronaut's "giant leap to prime crew".
Back with a vengeance
Shepard's place on the Apollo 13 flight looked assured, until Nasa's associate administrator George Mueller blocked the appointment.
The astronaut recalled in 1991: "The deal I tried to cut with Nasa was to give me command of Apollo 13. And they said 'Oh no. We can't do that, you are too much of a political problem.' I said: 'Well now, I've been training along with all these other guys, and I'm ready to go.'
"And they said, 'Well, we know that, but the public doesn't know that. So we will make a deal with you. We will let you command Apollo 14 if you will give us another crew for Apollo 13.' So Slayton and I gave them another crew."
Reg Turnill explains: "I was among those who were very surprised when [Shepard] became commander [of Apollo 14]. He didn't have any experience of previous flights at all.
"By then there was a steady routine that had been developed, to relieve the in-fighting among the astronauts. There were three crews to each mission. If you were on the back-up crew for a mission, you were more or less entitled to go two flights later."
In his book, Walt Cunningham details how the chance of a place on the Apollo 14 crew galvanised Shepard's resolve: "We underestimated how bad Al wanted that mission. No more emotional battles for him. The czar of the office, the steely-eyed stare, had decided to concentrate on his training and tilt no windmills," he writes.
After several years flying a desk, Shepard had to get back into shape: "Al went at it with a vengeance, including his physical conditioning programme," Walt Cunningham writes.
After the near-disaster of Apollo 13, Apollo 14 was regarded as a roaring success. As Shepard set foot on the lunar surface he said: "It's been a long way but we're here."
Whether age played a role or not, Shepard and Mitchell were worn out during their two spacewalks on the lunar surface. On their second moonwalk, they had to tow a two-wheeled trolley a mile (1.6km) to the rim of a crater.
In his book The Moonlandings, Reg Turnill recalls that after two hours and 10 minutes of the moonwalk had elapsed, the astronauts were nearly an hour behind schedule.
Shepard's heart rate had reached 150 and Mitchell's 128. They turned back before getting to the crater rim, forcing a geology experiment to roll boulders down the slopes to be abandoned.
Just before the astronauts were about to get back in their lunar module to prepare for the return to orbit, Shepard staged a memorable - though sometimes maligned - stunt, pulling two golf balls from a pocket in his space suit and dropping them into the powdery lunar soil.
Using a makeshift club comprising a six-iron specially modified so that it could attach to the extension handle for a scoop used to pick up lunar rock samples, Shepard drove the balls - one handed because of the restrictions of the space suit - as far as he could.
Shepard's age of 47 is hardly unusual for an astronaut today. In 1998, John Glenn - who became the first American to orbit Earth in a spacecraft - flew on a space shuttle mission at the grand old age of 77.