Mercury 4

Mercury 4 was a Mercury program manned space mission launched on July 21, 1961 using a Redstone rocket. Its capsule was named "Liberty Bell 7" and performed a suborbital flight piloted by astronaut Virgil (Gus) Grissom. It reached an altitude of 190.3 km.

The flight was identical to Mercury 3, but an accident upon splashdown caused the loss of the spacecraft when it filled with seawater. Grissom had insisted that the hatch could open by explosive bolts in case of emergency. It is believed that he accedently triggered the hatch, causing his spacecraft to rapidly fill with water. In his efforts to escape the sinking capsule, he forgot to close the oxygen port on his space suite. He tredded water as hard as he could, as his spaces suite got hevier and hevier. Due to the quick efforts of airborne rescue crews, Grissom escaped unhurt. Substantial controversy ensued as Grissom reported that the hatch had blown prematurely without his authorization. Engineering teams concluded this was unlikely. Mrs. Grissom was not invited to the White House as per the forming tradition with previous astronaut wives upon successful mission completion. Subsequent independent technical review of the incident has raised doubts as to the veracity of the incident report conclusions that Grissom blew the hatch and was responsible for the loss of the spacecraft. There is strong evidence that the Astronaut Office didn't buy into Grissom's guilt in the fact that he was chosen to command the first Gemini flight.

Liberty Bell 7 remained more than 15,000 feet deep on the bottom of the Atlantic Ocean until July 20, 1999, when it was raised by a team led by Curt Newport. It is now part of the collection of the Kansas Cosmosphere in Hutchinson, Kansas. The capsule's hatch was not found.

Ironically, the inability to swiftly open a hatch contributed to the death of Grissom and two other astronauts in the Apollo 1 launch-pad fire.

Crew

• Virgil Grissom

• Mass: 1286 kg
• Maximum Altitude: 190.3 km
• Range: 486 km
• Launch Vehicle: Redstone rocket