Mercury MA-7 Delta 7

Planned second US manned orbital flight. Cancelled 18 March 1962 when astronaut's minor heart condition became public.

Astronaut Deke Slayton was to have been the second American in orbit. When Slayton was selected as an astronaut in 1959, it was known he had a minor heart fibrillation. This however did not prevent him from being an Air Force test pilot or being selected as an astronaut. But on January 23, 1962 John Glenn's wife refused to do a television appearance with Vice President Lyndon Johnson after a launch scrub of Glenn's mission. Soon thereafter rumors began in McNamara's Pentagon that Glenn had a secret heart condition. It was not Glenn, and his flight went as planned, but in the process Slayton's heart fibrillation came up. After a series of quick developments, Slayton was told he couldn't fly, and was forced to appear at a press conference making that announcement on March 16. The action was seen by many as a warning to the astronauts who was really in charge, although Slayton didn't think there was a direct cause and effect. Slayton's three orbit flight would have been called Delta 7. Instead Carpenter was selected for the mission, and Schirra, Slayton's backup, was moved to the Mercury 8 flight.