Mercury-Atlas 7, nicknamed “Aurora 7,” was the science mission of the Mercury program — and the one that proved the fine line between exploration and disaster. Launched on May 24, 1962, from Cape Canaveral Launch Complex 14, the mission carried Navy Lieutenant Commander M. Scott Carpenter on three orbits of the Earth, repeating John Glenn’s historic flight profile but with a heavy emphasis on scientific experiments.

Carpenter was a scientist at heart, and his enthusiasm showed. He investigated Glenn’s mysterious “fireflies” — the glowing particles that Glenn had observed outside his window during Friendship 7 — and conclusively proved they were ice crystals from the spacecraft’s cooling system, dislodged when he tapped the capsule wall. He conducted the first study of liquid behavior in weightlessness, ate solid food in space, deployed an experimental inflatable balloon to study atmospheric drag, and took extensive photographs of the Earth’s limb and weather patterns.

But Carpenter’s fascination with science came at a cost. He spent so much time on experiments that he fell behind on his flight plan and used far more attitude-control fuel than budgeted. By the third orbit, fuel reserves were critically low. When it came time for retrofire, a combination of factors — late retrofire initiation, a 25-degree yaw error in spacecraft alignment, and the low fuel situation — caused Aurora 7 to overshoot its planned landing point by 250 miles. For 45 agonizing minutes, NASA and the watching world did not know if Carpenter had survived.

He had. Carpenter deployed his life raft and was recovered by helicopters and the USS Intrepid. The mission was declared a success scientifically, but Carpenter was criticized by some — most notably Flight Director Chris Kraft, who reportedly said “He will never fly again” — for prioritizing science over engineering discipline. Carpenter never flew in space again, instead transitioning to the Navy’s SEALAB underwater habitat program, where his skills as an explorer found a new frontier.