SpaceFacts

Alan Shepard's flight came just 23 days after Soviet cosmonaut Yuri Gagarin became the first human in space.

Shepard named the capsule Freedom 7 himself, continuing a tradition where each Mercury astronaut added '7' to represent the original Mercury Seven.

During a long prelaunch hold, Shepard had to urinate inside his spacesuit, since the mission was too short to plan for a bathroom break.

Frustrated by repeated delays, Shepard radioed Mission Control, 'Why don't you fix your little problem and light this candle?'

Freedom 7 never reached orbit; the Redstone rocket was too underpowered, so the flight followed a suborbital arc instead.

President Kennedy presented Shepard with the NASA Distinguished Service Medal at the White House shortly after the flight.

The entire flight, from launch to splashdown, lasted about the same time as a short commute.

Shepard's flight helped build the political confidence behind Kennedy's Moon landing challenge, delivered just twenty days later.

A decade after Freedom 7, Shepard commanded Apollo 14 and became the fifth person to walk on the Moon.

Liberty Bell 7 was the only Mercury capsule to have a triangular window added, giving Grissom a wider view than Shepard had on Freedom 7.

The capsule's explosive hatch used 70 small explosive charges around its edge, designed to blow outward in an emergency egress.

Investigators never conclusively determined why the hatch fired; Grissom insisted for the rest of his life that he never activated it.

Grissom's spacesuit began filling with water through an oxygen inlet valve he had left open for ventilation, nearly causing him to drown.

The rescue helicopter pilot later said the flooding capsule became so heavy it threatened to pull his own aircraft into the ocean.

Liberty Bell 7 rested in roughly 15,000 feet of water for 38 years before being recovered in 1999.

After conservation, Liberty Bell 7 went on public display at the Cosmosphere in Hutchinson, Kansas.

Grissom went on to command Gemini 3 in 1965 and was selected to command Apollo 1 before his death in the 1967 launch pad fire.

Glenn saw thousands of small, glowing particles drifting past his window during orbit, which he described as looking like fireflies.

The 'fireflies' were later identified as ice crystals shaken loose from the spacecraft's exterior, not any kind of atmospheric phenomenon.

A false sensor warning suggested the heat shield had come loose, leading engineers to keep the retrorocket package attached during reentry as a precaution.

That decision caused a dramatic, fiery reentry, with Glenn watching flaming debris from the burning retropack tumble past his window.

The heat shield had never actually loosened; the original warning turned out to be a faulty sensor reading.

Glenn took manual control of Friendship 7 for part of the flight after an autopilot malfunction.

An estimated four million people lined the streets of New York City for Glenn's ticker-tape parade.