He called his ship Freedom 7. His flight lasted all of 15 minutes and 28 seconds. He flew 116 miles above the earth's surface, was weightless for about five minutes, and splashed down in the Atlantic Ocean 300 miles from Cape Canaveral. He did not even have a window through which to admire the view.
But he became, that day, the first American ever to fly in space, and he is being quietly celebrated now.
"Daddy never thought of himself as a hero. He was just doing his job," said Shepard's daughter, Julie Shepard Jenkins, at a Florida ceremony Wednesday. His face appears on a new postage stamp to mark the anniversary.
Shepard died in 1998, and most Americans alive today were not born yet at the time of Freedom 7. So here are five things worth remembering about America's first astronaut. Ten, nine, eight, seven, six....
NASA, America's new space agency, said it would start flying astronauts in 1960. Easier said than done. Shepard's Mercury capsule was complicated to build, and its control system delayed the flight for months.
Its Redstone booster rocket was more trouble. After a less-than-smooth first test flight with a Mercury capsule on top, a second was ordered. Shepard and his fellow astronauts objected. His flight was delayed from March to May 1961.
In the meantime, he was upstaged. The Soviet Union launched Yuri Gagarin on April 12.
It may seem silly now, but Shepard's assignment to fly Freedom 7 was kept secret until the planned launch day. He was on a list with two fellow astronauts, John Glenn and Gus Grissom. On May 2, with the countdown in its final hours, it was Shepard who suited up and went to the launch pad. But the weather closed in and the flight was put off for three days.
People who knew him say Shepard was not reckless, but he was a test pilot with 8,000 hours of flying time. Riding a space capsule -- especially one on which he would essentially be a passenger -- was not that much of a challenge to him.
On May 5, as he lay on his back waiting for launch, a control system glitch kept him on the ground for two extra hours. Launch had been planned for 7 a.m. but soon it was 9:30. Everyone was worried except for Shepard. His biggest problem, the world learned later, was that his bladder was full.
"I've been in here more than three hours," he called to the control center. "I'm a hell of a lot cooler than you guys. Why don't you just fix your little problem and light this candle?"
That's what Shepard said during his five minutes of weightlessness, but he admitted later that the view wasn't much to write home about. In lieu of a window, Freedom 7 had a periscope that projected the view outside on a screen in front of him. Before launch, Shepard had flipped a gray filter into place because the rising sun was blinding.
After the launch he realized he had forgotten to remove the filter -- but the flight was so short, and the cabin so cramped, that he decided not to mess with it. Later astronauts would say they were moved by the Earth's beauty from space. Shepard missed it.
Freedom 7 lifted off at 9:34 a.m. on May 5, 1961, and splashed down in the Atlantic at 9:49. Shepard wanted to go again. He argued for a three-day flight in 1963, but it was canceled. He won assignment to command the first flight of NASA's new two-man Gemini spacecraft in 1964, but then developed an inner-ear disorder, Meniere's disease. It caused frequent bouts of vertigo, and he was grounded.
He was still a force at NASA, though, and kept lobbying for another flight. Finally, in 1969, after going in secret for corrective surgery, he was put back on active status -- and quickly assigned himself to command an Apollo moon flight. In 1971, on Apollo 14, he became the fifth man to walk on the Moon.
Years later he was asked what he thought his greatest accomplishment had been, and he said being chosen above the other Mercury astronauts to fly Freedom 7. Then he paused.
"I must admit," he said, "maybe I am a piece of history after all."