|Mission Name:||Mercury MR-4|
|Call Sign:||Liberty Bell 7|
|Number of Crew Members:||1|
|Launch:||July 21, 1961|
Cape Canaveral Complex 5
|Landing:||July 21, 1961|
|Duration:||15 minutes, 37 seconds|
|Number of Orbits:||None|
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 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.