Scott Carpenter, the second American to orbit Earth, died on Thursday at age 88.
Carpenter was one of the original Mercury 7 astronauts chosen by NASA in 1959.
Following Carpenter’s death, John Glenn is the only survivor of the pioneering astronauts, which included Alan Shepard, Wally Schirra, Gus Grissom, Deke Slayton, and Gordon Cooper.
The Mercury 7 weren’t just average American men. They were all military test pilots, but also college-educated as engineers and in superb physical condition.
Each man emerged from one of the world’s most competitive selection processes that included a daunting combination of interviews, written exams, mental evaluations, and stress tests.
What followed were two years of intensive training before risking everything to become the first Americans to rocket into space.
Selection of the Mercury astronauts began in January 1959. Due to the rigors of space travel, only military test pilots from the U.S. Air Force, Navy, and Marine Corps were considered for America's first manned space program.
Candidates had to be younger than 40, no taller than 5' 11', and weigh no more than 180 pounds (due to the small size of the Mercury space capsule). They were also required to hold a bachelor's degree in engineering, have graduated test pilot school, and have 1,500 hours of flying time.
30-two men who made it through a tough interview process in Washington, D.C, were sent to Lovelace Clinic in Albuquerque, New Mexico, where psychological and physical tests were conducted.
Test pilots were poked, probed, and measured for things like blood volume, water volume and total-body radiation count.
After one week of medical evaluations, the pilots were shipped off to Wright Air Development Center for Phase 4 of the selection program.
Each candidate had to prove his physical endurance through an elaborate series of vibration, heat, and pressure tests.
A candidate prepares to be whipped around in a human centrifuge, used to expose astronauts to g-forces they would experience during launch and re-entry.
Candidates were evaluated on their responses to questions like 'Who am I?' and 'Whom would you assign to the mission if you could not go yourself?'
NASA introduced the 'Mercury Seven' to the public at a press conference in Washington, D.C. On April 9, 1959.
That month, the Original Seven reported to the Manned Spacecraft Center in Texas (later named the Johnson Space Center), for two years of training.
During the training period, astronauts spent hours in the classroom mastering the details of the Mercury craft and learning more about meteorology and engineering.
Contraptions like the Gimbal Rig simulated an uncontrolled spin in space flight. Nitrogen-gas jets twisted three aluminium cages around at speeds up to 30 revolutions per minute. The pilot was strapped into a plastic seat at the center of the cage, leaving only his arms free.
Zero-gravity flights, nicknamed the 'vomit comet' because of the nausea it often produces, were used to simulate weightlessness.
To prepare for landing off-course, the astronauts were left in the Nevada desert for four days with a mockup of the Mercury spacecraft, a parachute and a survival scenario. They emerged with clothing made out of the parachute material and beards.
Their training efforts ultimately paid off. On May 5, 1961, Alan Shepard became the first American in space, aboard Freedom 7.
Over the next two years, six of the Original Seven (Slayton was the exception) flew Mercury missions. The five-year-program, which also included five unmanned flights, paved the way for future human space travel.
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