Written By: Ben Cosgrove

Men and women have been rocketing into space from the Earth’s surface for the past half-century—long enough that much of the general public now views space missions as relatively safe, rote endeavors. 

But the business of space exploration is not, and has never been, safe. Here, LIFE.com recalls one of the worst disasters in NASA’s history—and its first public tragedy—when astronauts Gus Grissom, Ed White and Roger Chaffee died in a fire inside their command module on a Cape Canaveral launchpad on Jan. 27, 1967. As TIME’s Jeffrey Kluger (the author of Apollo 13) once wrote, when commemorating the three astronauts:

Test pilots can sense straightaway if they’re working with a good vehicle or a bad one, and the Apollo 1 crew . . . knew almost immediately that they’d been assigned to a stinker. By late 1966, the last of the sturdy, two-man Gemini spacecraft had flown, and NASA was rolling out the three-man Apollo ships that would, at last, carry men to the moon. The spacecraft were sweet-looking machines, but in test-runs on the pad, they were a mess. The electrical system fritzed, the communications died, repairs and upgrades were late in coming. . . . Most worrisome, however, was NASA’s insistence on continuing to use 100% pure oxygen in its atmospheric systems an explosively flammable gas that had worked fine so far in the Mercury and Gemini ships but that could burn like gasoline in the presence of so much as an errant spark . . . Early one Friday evening, when the Apollo 1 astronauts were locked down in the spacecraft for a practice session out on the pad, just such a spark got loose from a frayed wire next to Grissom’s seat. In less than a minute, all three men were dead. For a while, it seemed, the Apollo program would perish too.

The program, of course, survived, and less than three years after the 1967 launchpad fire, Neil Armstrong, Buzz Aldrin and Michael Collins flew Apollo 11 to the moon and back—leaving human footprints on the lunar surface—in what some consider the signature triumph of the 20th century.

Liz Ronk edited this gallery for LIFE.com. Follow her on Twitter at @LizabethRonk.

American astronauts Ed White, Roger Chaffee and Gus Grissom in the Apollo Mission Simulator, a replica of the capsule in which they died.

American astronauts Ed White, Roger Chaffee and Gus Grissom in the Apollo Mission Simulator, a replica of the capsule in which they died.

Ralph Morse The LIFE Picture Collection/Getty Images

Readying for Apollo I tests, Cape Canaveral, Fla., 1966.

Readying for Apollo I tests, Cape Canaveral, Fla., 1966.

Ralph Morse The LIFE Picture Collection/Getty Images

Apollo I astronauts (l-r) Roger Chaffee, Ed White and Gus Grissom, Fla.

Apollo I astronauts (left to right) Roger Chaffee, Ed White and Gus Grissom, Fla.

Ralph Morse The LIFE Picture Collection/Getty Images

Apollo 1 astronauts (l-r) Gus Grissom, Ed White and Roger Chaffee, photographer the week before the fatal fire at Pad 34, from which their mission was to have launched in February 1967.

Apollo 1 astronauts (left to right) Gus Grissom, Ed White and Roger Chaffee, photographed the week before the fatal fire at Pad 34, from which their mission was to have launched in February 1967.

Ralph Morse The LIFE Picture Collection/Getty Images

Apollo 1 astronauts Roger Chaffee, Ed White and Gus Grissom, 1967.

Apollo 1 astronauts Roger Chaffee, Ed White and Gus Grissom, 1967.

Ralph Morse The LIFE Picture Collection/Getty Images

Apollo 1 astronauts (front to back) Roger Chaffee, Ed White and Gus Grissom, Cape Kennedy, Fla.

Apollo 1 astronauts (front to back) Roger Chaffee, Ed White and Gus Grissom, Cape Kennedy, Fla.

Ralph Morse The LIFE Picture Collection/Getty Images

Roger Chaffee with his wife Martha and their children, Sheryl and Stephen, in their Houston home, 1965.

Roger Chaffee with his wife Martha and their children, Sheryl and Stephen, in their Houston home, 1965.

Ralph Morse The LIFE Picture Collection/Getty Images

Astronaut Ed White leaps off a truck before an attentive audience of his fellow astronauts during a training exercise, 1963.

Astronaut Ed White leapt off a truck before an attentive audience of his fellow astronauts during a training exercise, 1963.

Ralph Morse The LIFE Picture Collection/Getty Images

In a husband-and-wife appearance before the press, Pat and Ed White (far left) and Pat and Jim McDivitt share delight with the news that President Johnson has promoted the astronauts after the flight of Gemini 4 in 1965.

In a husband-and-wife appearance before the press, Pat and Ed White (far left) and Pat and Jim McDivitt shared delight with the news that President Johnson had promoted the astronauts after the flight of Gemini 4 in 1965.

Francis Miller The LIFE Picture Collection/Getty Images

NASA astronaut Ed White and his wife Pat at home.

NASA astronaut Ed White and his wife Pat at home.

Ralph Morse The LIFE Picture Collection/Getty Images

During a family work-out on the horizontal bar, Bonnie Lynn and Eddie White compete against their father, astronaut Ed White.

During a family work-out on the horizontal bar, Bonnie Lynn and Eddie White competed against their father, astronaut Ed White.

Ralph Morse The LIFE Picture Collection/Getty Images

Astronaut Edward White and family, Houston.

Astronaut Ed White and family, Houston.

Ralph Morse The LIFE Picture Collection/Getty Images

Astronaut Edward White and family, Houston.

Astronaut Ed White and family, Houston.

Ralph Morse The LIFE Picture Collection/Getty Images

Astronaut Gus Grissom in his space suit.

Astronaut Gus Grissom in his space suit.

Ralph Morse The LIFE Picture Collection/Getty Images

Gus Grissom often found relief from the pressures of being an astronaut simply by going fishing. He casts for sea bass near Cape Kennedy.

Gus Grissom often found relief from the pressures of being an astronaut simply by going fishing. He cast for sea bass near Cape Kennedy.

Ralph Morse The LIFE Picture Collection/Getty Images

Astronaut Gus Grissom with his sons.

Astronaut Gus Grissom with his sons.

Ralph Morse The LIFE Picture Collection/Getty Images

Home a hero after his successful 1965 mission in Gemini 3, [Gus Grissom] greeted his parents who came from Mitchell, Ind. for the flight.

Home a hero after his successful 1965 mission in Gemini 3, [Gus Grissom] greeted his parents who came from Mitchell, Ind. for the flight.

Ralph Morse The LIFE Picture Collection/Getty Images

Gus Grissom at home with his son.

Gus Grissom at home with his son.

Ralph Morse The LIFE Picture Collection/Getty Images

114363332.jpgGus Grissom with his wife Betty and their sons Scott and Mark.

Gus Grissom with his wife Betty and their sons Scott and Mark.

Ralph Morse The LIFE Picture Collection/Getty Images

Apollo I and II crews

In seclusion at a private home high in the Hollywood Hills, the prime crews for the first and second Apollo flights spent two days earlier this winter in an intensive but informal review of flight plans. Grouped around the table were Gus Grissom (far left), Ed White, Roger Chaffee (back showing), Rusty Schweickart (above), Jim McDivitt and Dave Scott (far right).

Ralph Morse The LIFE Picture Collection/Getty Images

LIFE magazine, February 3, 1967

LIFE magazine, February 3, 1967

LIFE magazine, February 3, 1967

LIFE magazine, February 3, 1967

LIFE magazine, February 3, 1967

LIFE magazine, February 3, 1967

LIFE magazine, February 3, 1967

LIFE magazine, February 3, 1967

LIFE magazine, February 3, 1967

LIFE magazine, February 3, 1967.

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