On October 4, 1957, the USSR scored the first victory of the "space race" when it successfully launched the world's first artificial satellite, Sputnik, into Earth's orbit. In response, the United States consolidated its various military and civilian space efforts into NASA, which dedicated itself to beating the Soviets to manned space flight. In January 1959, NASA began the astronaut selection procedure, screening the records of 508 military test pilots and choosing 110 candidates. This number was arbitrarily divided into three groups, and the first two groups reported to Washington. Because of the high rate of volunteering, the third group was eliminated. Of the 62 pilots who volunteered, six were found to have grown too tall since their last medical examination. An initial battery of written tests, interviews, and medical history reviews further reduced the number of candidates to 36. After learning of the extreme physical and mental tests planned for them, four of these men dropped out.
The final 32 candidates traveled to the Lovelace Clinic in Albuquerque, New Mexico, where they underwent exhaustive medical and psychological examinations. The men proved so healthy, however, that only one candidate was eliminated. The remaining 31 candidates then traveled to the Wright Aeromedical Laboratory in Dayton, Ohio, where they underwent the most grueling part of the selection process. For six days and three nights, the men were subjected to various tortures that tested their tolerance of physical and psychological stress. Among other tests, the candidates were forced to spend an hour in a pressure chamber that simulated an altitude of 65,000 feet, and two hours in a chamber that was heated to 130 degrees Fahrenheit. At the end of one week, 18 candidates remained. From among these men, the selection committee was to choose six based on interviews, but seven candidates were so strong they ended up settling on that number.
After they were announced, the "Mercury Seven" became overnight celebrities. The Mercury Project suffered some early setbacks, however, and on April 12, 1961, Soviet cosmonaut Yuri Gagarin orbited Earth in the world's first manned space flight. Less than one month later, on May 5, astronaut Alan Shepard was successfully launched into space on a suborbital flight. On February 20, 1962, in a major step for the U.S. space program, John Glenn became the first American to orbit Earth. NASA continued to trail the Soviets in space achievements until the late 1960s, when NASA's Apollo program put the first men on the moon and safely returned them to Earth.
In 1998, 36 years after his first space flight, John Glenn traveled into space again. Glenn, then 77 years old, was part of the Space Shuttle Discovery crew, whose 9-day research mission launched on October 29, 1998. Among the crew's investigations was a study of space flight and the aging process.