Scenes from the Mercury-Redstone 4 mission on July 21, 1961 when Mercury astronaut Gus Grissom became the second American to fly in space. After a suborbital flight lasting 15 minutes and 37 seconds, a problem with the hatch of his spacecraft “Liberty Bell 7” led his capsule to sink after splashdown. It was salvaged from the Atlantic in 1999. (NASA)