Mercury-Redstone 4 was America’s second crewed suborbital spaceflight, and it should have been a straightforward repeat of Alan Shepard’s triumphant mission eleven weeks earlier. Instead, it became one of the most dramatic and controversial events in the early space program. On July 21, 1961, Air Force Captain Virgil I. “Gus” Grissom rode Liberty Bell 7 on a near-perfect 15-minute ballistic arc to an apogee of 118.3 miles — slightly higher than Shepard’s flight — before the mission went terribly wrong after splashdown.

The flight itself was flawless. Grissom launched from Cape Canaveral’s LC-5 at 7:20 AM EDT, experienced the same brief weightlessness and stunning view of the Florida coast, and manually controlled the spacecraft’s attitude just as Shepard had. Liberty Bell 7 featured a new explosive side hatch designed for rapid emergency egress — a crucial improvement over Freedom 7’s cumbersome bolted hatch. But moments after the capsule splashed down in the Atlantic Ocean 303 miles downrange, the explosive hatch blew prematurely while Grissom was still inside.

Seawater rushed into the capsule. Grissom scrambled out and found himself treading water in a sinking spacecraft, his suit filling with water through an open oxygen inlet. The recovery helicopter hooked onto Liberty Bell 7 and tried to lift it, but the flooded capsule was too heavy — over 5,000 pounds — and the helicopter’s engine began to overheat. The pilot had to cut the capsule loose, and Liberty Bell 7 sank in 15,000 feet of water. Grissom, struggling to stay afloat, was finally pulled to safety by a second helicopter.

A fierce debate erupted over whether Grissom had accidentally triggered the hatch. He always maintained his innocence, insisting the hatch fired on its own. Many engineers supported him, noting that the firing mechanism required a deliberate blow with the side of the fist, and that Grissom had no hand injuries. He was never formally blamed, but the cloud of suspicion haunted him for years. Grissom went on to command Gemini 3 in 1965 — jokingly naming his capsule “Molly Brown” after the unsinkable heroine. Tragically, Grissom died in the Apollo 1 cabin fire on January 27, 1967, along with Ed White and Roger Chaffee. In 1999, oceanographer and salvage expert Curt Newport led an expedition that recovered Liberty Bell 7 from the ocean floor after 38 years, finally bringing the capsule home.