In the winter of 1962, the nation needed a hero.

Americans had yet to recover from the Soviet Union’s launching of the first spacecraft, Sputnik, in October 1957 — a rude jolt to our confidence as world leaders in all things technological. The space race was on.

Soon after he took office in 1961, President John F. Kennedy had thrown down the challenge to send men to the moon by the end of the decade. But the Russians still set the pace, boastfully. They launched a dog into orbit, then the first man, Yuri Gagarin, and another, Gherman Titov.

The United States lagged, managing only two 15-minute suborbital astronaut flights — only five minutes of weightlessness each time.

Then, on Feb. 20, 1962 — 50 years ago next Monday — a Marine Corps fighter pilot from small-town America stepped forward in response to the country’s need. The astronaut was John Glenn, whom the author Tom Wolfe has called “the last true national hero America has ever had.”

Squeezed into the cockpit of a Mercury spacecraft called Friendship 7, launched by an Atlas rocket from Cape Canaveral, Fla., Glenn circled the Earth three times, becoming the first American to orbit the planet. Perhaps no other spaceflight — all four hours, 55 minutes and 23 seconds of it — has been followed by so many with such paralyzing apprehension.

Glenn saw three sunsets and sunrises that Tuesday, from a maximum altitude of 162 miles. At each sunrise, an explosion of what looked like fireflies appeared outside the window, mystifying him. Then came a signal of a suspected problem that had ground controllers bracing for an uncertain, possibly catastrophic re-entry into the atmosphere.

The ending was a happy one. A collective sigh of relief was heard across the land. The president rushed off to Cape Canaveral to hail the returning hero. Bands played. Ticker tape streamed from the high windows of Broadway. People cried. Never mind that a Soviet cosmonaut had already spent 25 hours in orbit. As Wolfe has written, “John Glenn made us whole again!”

Now, at 90, Glenn was reminded in one of two lengthy interviews that the author of “The Right Stuff” had judged him the country’s last true hero. His response was a kind of dismissive aw shucks. “Hero” is an elastic word, after all, stretchable to fit a favorite ballplayer or a great conqueror in war or discovery — almost anyone admirable.

“I don’t think of myself that way,” Glenn said. “I get up each day and have the same problems others have at my age. As far as trying to analyze all the attention I received, I will leave that to others.”

(For his part, Wolfe stood by his characterization, saying a national hero was someone seen as “a great protector” of the people. “He really wasn’t their protector, but that’s what people felt and thought,” he said of Glenn in an interview last week. “He made them cry, and this made him a hero.”)

Mercury reunion

On Saturday, Glenn will again get a hero’s welcome at Cape Canaveral for a reunion with the dwindling Mercury space team, those remaining managers, engineers and technicians who sent the first Americans into space. On Monday and Tuesday, he will be honored with a dinner and a spaceflight forum at Ohio State University, home of the John Glenn School of Public Affairs.

Glenn keeps an office at the school, holds seminars with students and is close to the archive of papers from his careers as an astronaut and, later, a four-term United States senator from Ohio and a candidate in the 1984 Democratic presidential primaries. It is quite an archive: about 1,800 boxes of materials. “I was a pack rat,” he said.

He and his wife, Anna (he calls her Annie), divide their time between a house in a suburb of Washington and a condominium in Columbus. She was his childhood sweetheart, and their marriage has stood the test of almost 69 years of devotion in the turbulence of spaceflight and politics.

The other honored guest at the anniversary events in Cape Canaveral will be M. Scott Carpenter, the Mercury astronaut who was Glenn’s backup and radio link, called capcom, in the launching blockhouse that day of flight. The two are the only surviving members of what were known as the Mercury Seven. Virgil Grissom died in 1967 in an Apollo spacecraft fire during a launching-pad test. Donald Slayton died of cancer in 1993. Alan Shepard Jr. died of leukemia in 1998. L. Gordon Cooper Jr. died of natural causes in 2004. Walter Schirra Jr. died of a heart attack in 2007.

In 1998, his last year in the Senate, the first American to orbit Earth became, at 77, the oldest person to travel in space. Glenn felt he still had enough of the right stuff. He had continued to pilot his own airplane and had kept in shape — “attitude and exercise,” he said, “that’s what keeps you going” — and he persuaded NASA to let him fly on the space shuttle Discovery and conduct tests on the physiological effects of nine days of weightlessness on older people.

As Glenn settled into recollections of that February day in 1962, the interview glided into easy conversation over shared memories. Ten times over almost a month the launching was scheduled, only to be scrubbed because of poor weather or mechanical glitches. “On again, off again,” Glenn said. “I actually suited up four times, and two times was up on top of the Atlas, strapped into Friendship 7, ready to go.”

Reporters from all over the world grew restive, desperate for anything to write about. After one cancellation, Mercury information officers begged Glenn to give them something to tell the journalists. When he got off the booster, he went running on the beach and happened to see where sea turtles had buried their eggs. This was duly reported, and one writer remarked that it was understood the astronaut had a good recipe for turtle egg soup.

“Well, that got me into a whole lot of trouble with environmentalists,” Glenn recalled. “I got mail calling me everything but a good guy, and should be replaced.”

Waiting …

The waiting got so tiresome for the press corps that when a waitress at one of the watering holes was shot dead by her boyfriend around midnight, some reporters rushed to file the story. A London tabloid declared it “the first successful shot here in weeks.”

Glenn said he had not heard that tale before.

At last, on the 11th attempt, with his backup, Carpenter, bidding “Godspeed, John Glenn,” Friendship 7 lifted off for its three orbits of Earth. Christopher Kraft Jr., the flight director, remembers, “Nothing about John Glenn’s flight was easy.”

At first sunrise, Glenn saw a swarm of greenish-yellow lights outside the craft, reminding him of fireflies. He saw them again at the other sunrises. “No one had anticipated this, and it was fascinating,” he said. “Turns out these were tiny moisture particles vented from the heat-exchange system, but I don’t know if we have ever explained their particular colors.”

Near the end of the first orbit, trouble with the automatic control system forced Glenn to take manual control for much of the remaining orbits. He felt he was truly the pilot, not a passenger on autopilot. Not “Spam in a can,” in the minds of the veteran test pilots unimpressed by these new astronauts.

Then a signal sent to the ground warned of a potentially more serious problem. It indicated that the craft had a loose heat shield. Flight controllers suspected it was a spurious signal, but could not be sure. They decided not to jettison the retro rockets after they braked the capsule for its descent. The retro-pack should keep the heat shield in place and prevent serious damage to the capsule.

“Glancing out the window during re-entry,” Glenn recalled, “I was seeing big chunks of something coming off. It was the retro-pack, not the heat shield, thank goodness. It had been a false alarm. If you go to the Air and Space Museum in Washington, you can see the burn patterns on Friendship 7.”

In the epilogue to “The Right Stuff,” his best-seller on the original seven astronauts, Wolfe wrote that the day of Glenn the hero “when an astronaut could parade up Broadway while traffic policemen wept in the intersections,” was no more. An era, he continues, “had come, and it had gone, perhaps never to be relived.”

But in a time short of heroes, John Glenn keeps alive the memory.