CAPE CANAVERAL, Fla. -- Former space shuttle launch director, Bob Sieck, talks to guests in the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida. Sieck is helping John Glenn mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard space shuttle Discovery's STS-95 mission. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- U.S. Rep. Bill Posey listens to remarks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronauts, John Glenn, left, and Scott Carpenter, talk to Mercury Project workers and other guests in the Astronaut Encounter Theater at the Kennedy Space Center Visitor Complex in Florida. The pair participated in 50th anniversary events at the launch site of Glenn's first orbital flight aboard NASA's Friendship 7 capsule, which launched Feb. 20, 1962, aboard an Atlas rocket. At right, is Jack King, who was chief of Kennedy's Public Information Office during Project Mercury. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronauts John Glenn, second from left and Scott Carpenter look around at the dismantled Complex 14 at Cape Canaveral Air Force Station in Florida. Glenn and Carpenter launched from the pad on Atlas rockets inside Mercury capsules in 1962. The two astronauts, part of the original class of seven astronauts chosen by NASA, were taking part in events celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/ Cory Huston

CAPE CANAVERAL, Fla. --A crowd looks on during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut John Glenn poses for a photo in front of the Project Mercury monument at Launch Complex-14 LC-14 at Cape Canaveral Air Force Station in Florida. During events at the Cape and NASA's Kennedy Space Center, Glenn is marking the 50th anniversary of being the first American astronaut to orbit the Earth inside the Friendship 7 capsule on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- John Glenn signs the wall of the clean room leading into space shuttle Discovery in Orbiter Processing Facility-1 OPF-1 at NASA's Kennedy Space Center in Florida. Glenn is at the space center to mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- Mercury astronaut John Glenn speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. - Former Kennedy Space Center directors Jay Honeycutt, left, and Bob Crippen, right, talk during a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut John Glenn speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. - Former Kennedy Space Center directors Jay Honeycutt, left, Roy Bridges and NASA Administrator Charles Bolden talk with astronaut John Glenn before a luncheon Feb. 17, 2012 celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Former Kennedy Space Center directors Forrest McCartney, left, and Roy Bridges, center, listen with Annie Glenn during a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut Scott Carpenter speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- A crowd looks on during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA Kennedy Space Center Director Bob Cabana talks to guests in Orbiter Processing Facility-1 OPF-1 where space shuttle Discovery is being prepared for public display during a 50th anniversary celebration of the first orbital flight of an American. The astronaut who made that first flight, John Glenn, is at the space center to commemorate that achievement. Glenn orbited the Earth three times in the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. He later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. - Kennedy Space Center Director Bob Cabana, standing, speaks during a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- John Glenn and his wife, Annie, and NASA astronaut Stephen Robinson stand under space shuttle Discovery in Orbiter Processing Facility-1 OPF-1 at NASA's Kennedy Space Center in Florida. Glenn is at the space center to mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Robinson was the payload commander of STS-95. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- NASA Kennedy Space Center Director Bob Cabana, right, talks to guests in Orbiter Processing Facility-1 OPF-1 where space shuttle Discovery is being prepared for public display during a 50th anniversary celebration of the first orbital flight of an American. The astronaut who made that first flight, John Glenn, is at the space center to commemorate that achievement. Glenn orbited the Earth three times in the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. He later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Also in the photo are Glenn's wife, Annie, NASA astronaut Stephen Robinson, and Bob Sieck, a former shuttle launch director. Robinson was the payload commander of STS-95. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- Mercury astronauts John Glenn, left, and Scott Carpenter sit in front of the plot board from the Mercury control center on display at the Kennedy Space Center Visitor Complex. The astronauts, part of the original class of seven astronauts chosen by NASA, were taking part in a question-and-answer session with the media as part of events celebrating 50 years of Americans in orbit, an era which began with John Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. --Mercury astronaut John Glenn listens to remarks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. - Ed Mango, program manager of NASA's Commercial Crew Program, left, talks with astronaut John Glenn, center and NASA Administrator Charles Bolden before a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA Kennedy Space Center Bob Cabana talks to a guest about the Mercury Project's Atlas rocket in the Vehicle Assembly Building. At the space center in Florida, Cabana is helping John Glenn mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard space shuttle Discovery's STS-95 mission. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- Mercury astronauts Scott Carpenter, left, and John Glenn listen to remarks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronauts Scott Carpenter, left, and John Glenn and astronaut Steve Robinson of STS-95 listen to remarks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. - Former Kennedy Space Center directors Forrest McCartney and Roy Bridges join Annie Glenn, astronaut John Glenn and NASA Administrator Charles Bolden during a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-95 astronaut Steve Robinson speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronauts Scott Carpenter, left, and John Glenn sit in front of a capsule from the Mercury program on display at the Kennedy Space Center Visitor Complex in Florida. The two astronauts, part of the original class of seven astronauts chosen by NASA, were taking part in events celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - NASA Administrator Charles Bolden, left, shares a laugh with astronaut John Glenn before a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronauts Scott Carpenter, left, and John Glenn and astronaut Steve Robinson of STS-95 listen to remarks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- U.S. Rep. Bill Posey, left, prepares to ride in the Corvette parade following the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- John Zarella makes remarks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA Kennedy Space Center Director Bob Cabana sits at the controls in the flight deck of space shuttle Discovery in Orbiter Processing Facility-1 OPF-1. At the space center in Florida, Cabana is helping John Glenn mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- Cal Fowler, Launch test director during Mercury, speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut Scott Carpenter, center, prepares to ride in the Corvette parade following the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -Annie Glenn and astronaut John Glenn listen during a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut John Glenn sits in front of the plot board from the Mercury control center on display at the Kennedy Space Center Visitor Complex in Florida. The astronaut, part of the original class of seven astronauts chosen by NASA, was taking part in a question-and-answer session with the media as part of events celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut John Glenn speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Former space shuttle launch director, Bob Sieck, left, talks to guests in the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida. Sieck is helping John Glenn mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard space shuttle Discovery's STS-95 mission. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- John Glenn and his wife, Annie, and NASA astronaut Stephen Robinson tour the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida. Glenn is at the space center to mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard space shuttle Discovery's STS-95 mission. Robinson was the payload commander of STS-95. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- Mercury astronauts, John Glenn, left, and Scott Carpenter, talk to Mercury Project workers and other guests in the Astronaut Encounter Theater at the Kennedy Space Center Visitor Complex in Florida. The pair participated in 50th anniversary events at the launch site of Glenn's first orbital flight aboard NASA's Friendship 7 capsule, which launched Feb. 20, 1962, aboard an Atlas rocket. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. - Kennedy Space Center Director Bob Cabana, from left, Mercury astronaut John Glenn, NASA Administrator Charles Bolden and Mercury astronaut Scott Carpenter pose during a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut John Glenn, left, prepares to ride in the Corvette parade following the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- John Glenn tours the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida. Glenn is at the space center to mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard space shuttle Discovery's STS-95 mission. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- Mercury astronaut Scott Carpenter listens to remarks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. --Kennedy Space Center Director Bob Cabana, left, prepares to ride in the Corvette parade following the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -Annie Glenn, left, astronaut John Glenn and NASA Administrator Charles Bolden take part in a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Annie Glenn, center, speaks as former Kennedy Space Center director Roy Bridges, left, and astronaut John Glenn look on during a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. --John Zarella leads a standing ovation during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. --Mercury astronaut John Glenn speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. --Kennedy Space Center Director Bob Cabana makes remarks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. Looking on are U.S. Rep. Bill Posey, left, and event MC John Zarella. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. - Mercury astronaut John Glenn, left, talks with Kennedy Space Center Director Bob Cabana during a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- John Glenn and his wife, Annie, and NASA astronaut Stephen Robinson stand under space shuttle Discovery in Orbiter Processing Facility-1 OPF-1 at NASA's Kennedy Space Center in Florida. Glenn is at the space center to mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Robinson was the payload commander of STS-95. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- The international news media takes part in a question-and-answer session with Mercury astronauts John Glenn and Scott Carpenter at the Kennedy Space Center Visitor Complex in Florida. The astronauts, part of the original class of seven astronauts chosen by NASA, were taking part in events celebrating 50 years of Americans in orbit, an era which began with John Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA Kennedy Space Center Bob Cabana talks to guests about the Mercury Project's Atlas rocket in the Vehicle Assembly Building. At the space center in Florida, Cabana is helping John Glenn mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard space shuttle Discovery's STS-95 mission. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- John Glenn and his wife, Annie, and NASA astronaut Stephen Robinson stand under space shuttle Discovery in Orbiter Processing Facility-1 OPF-1 at NASA's Kennedy Space Center in Florida. Glenn is at the space center to mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Robinson was the payload commander of STS-95. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- Former space shuttle launch director, Bob Sieck, left, talks to guests in the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida. Sieck is helping John Glenn mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard space shuttle Discovery's STS-95 mission. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. - NASA Administrator Charles Bolden, left, talks with astronaut John Glenn and his wife, Annie Glenn, before a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut John Glenn poses for a photo in front of the Project Mercury monument at Launch Complex-14 LC-14 at Cape Canaveral Air Force Station in Florida. During events at the Cape and NASA's Kennedy Space Center, Glenn is marking the 50th anniversary of being the first American astronaut to orbit the Earth inside the Friendship 7 capsule on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Lisa Malone, left, director of Public Affairs at NASA's Kennedy Space Center in Florida, talks with Mercury astronauts John Glenn, center, and Scott Carpenter in front of the plot board from the Mercury control center on display at the Kennedy Space Center Visitor Complex. The astronauts, part of the original class of seven astronauts chosen by NASA, were taking part in a question-and-answer session with the media as part of events celebrating 50 years of Americans in orbit, an era which began with John Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. --Mercury astronaut Scott Carpenter speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronauts, John Glenn, left, and Scott Carpenter, talk to Mercury Project workers and other guests in the Astronaut Encounter Theater at the Kennedy Space Center Visitor Complex in Florida. The pair participated in 50th anniversary events at the launch site of Glenn's first orbital flight aboard NASA's Friendship 7 capsule, which launched Feb. 20, 1962, aboard an Atlas rocket. At right, is Jack King, who was chief of Kennedy's Public Information Office during Project Mercury. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- U.S. Sen. Bill Nelson speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. - Mercury astronaut Scott Carpenter signs a poster celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Kennedy Space Center Director Bob Cabana makes remarks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronauts, John Glenn, left, and Scott Carpenter, talk to Mercury Project workers and other guests in the Astronaut Encounter Theater at the Kennedy Space Center Visitor Complex in Florida. The pair participated in 50th anniversary events at the launch site of Glenn's first orbital flight aboard NASA's Friendship 7 capsule, which launched Feb. 20, 1962, aboard an Atlas rocket. At right, is Jack King, who was chief of Kennedy's Public Information Office during Project Mercury. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- At Launch Complex-14 LC-14 at Cape Canaveral Air Force Station in Florida, a memorial honors the 13 crew members of the U.S. Air Force's 32nd Air Division, 40th Troop Carrier and 317th Consolidated Aircraft Maintenance Squadron, who were killed in a C-130A transport plane crash near Nairobi, Kenya, during a contingency mission for NASA's Project Mercury in 1962. The crash happened 50 years ago, after John Glenn's orbital flight on Feb. 20, 1962, and before Scott Carpenter's on May 24, 1962. Glenn and Carpenter participated in 50th anniversary commemorative events at the Cape and NASA's Kennedy Space Center and stopped by the memorial to honor the Airmen who made the ultimate sacrifice making a distinctive service to their country.

CAPE CANAVERAL, Fla. --Mercury astronaut Scott Carpenter speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronauts, John Glenn, left, and Scott Carpenter, talk to Mercury Project workers and other guests in the Astronaut Encounter Theater at the Kennedy Space Center Visitor Complex in Florida. The pair participated in 50th anniversary events at the launch site of Glenn's first orbital flight aboard NASA's Friendship 7 capsule, which launched Feb. 20, 1962, aboard an Atlas rocket. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Astronaut Steve Robinson of STS-95, left, Cal Fowler, Launch test director during Mercury, U.S. Rep. Bill Posey, U.S. Sen. Bill Nelson and Kennedy Space Center Director Bob Cabana listen to remarks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- John Glenn and NASA Kennedy Space Center Director Bob Cabana sit in the flight deck of space shuttle Discovery in Orbiter Processing Facility-1 OPF-1. Glenn is at the space center to mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. - Mercury astronauts John Glenn, left, and Scott Carpenter pose during a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- John Glenn and his wife, Annie, and NASA astronaut Stephen Robinson stand beside the wheel of space shuttle Discovery in Orbiter Processing Facility-1 OPF-1 at NASA's Kennedy Space Center in Florida. Glenn is at the space center to mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Robinson was the payload commander of STS-95. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- Mercury astronauts John Glenn, left, and Scott Carpenter sit in front of the plot board from the Mercury control center on display at the Kennedy Space Center Visitor Complex. The astronauts, part of the original class of seven astronauts chosen by NASA, were taking part in a question-and-answer session with the media as part of events celebrating 50 years of Americans in orbit, an era which began with John Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Mercury astronaut John Glenn signs a poster celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut John Glenn listens to remarks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut Scott Carpenter speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -NASA Administrator Charles Bolden, left, talks with astronaut John Glenn following a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Kennedy Space Center Director Bob Cabana, center, talks with U.S. Rep. Bill Posey, left and U.S. Sen. Bill Nelson following the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-95 astronaut Steve Robinson speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. --Mercury astronauts John Glenn, left, and Scott Carpenter sit in front of the plot board from the Mercury control center on display at the Kennedy Space Center Visitor Complex. The astronauts, part of the original class of seven astronauts chosen by NASA, were taking part in a question-and-answer session with the media as part of events celebrating 50 years of Americans in orbit, an era which began with John Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut Scott Carpenter sits in front of the plot board from the Mercury control center on display at the Kennedy Space Center Visitor Complex in Florida. The astronaut, part of the original class of seven astronauts chosen by NASA, was taking part in a question-and-answer session with the media as part of events celebrating 50 years of Americans in orbit, an era which began with John Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. --Mercury astronauts John Glenn, left, and Scott Carpenter sit in front of the plot board from the Mercury control center on display at the Kennedy Space Center Visitor Complex in Florida. The astronaut, part of the original class of seven astronauts chosen by NASA, was taking part in a question-and-answer session with the media as part of events celebrating 50 years of Americans in orbit, an era which began with John Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- John Glenn and NASA astronaut Stephen Robinson sit in the flight deck of space shuttle Discovery in Orbiter Processing Facility-1 OPF-1 at NASA's Kennedy Space Center in Florida. Glenn is at the space center to mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Robinson was the payload commander of STS-95. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- Hugh Harris, the former director of Public Affairs at NASA's Kennedy Space Center in Florida, talks to Mercury Project workers and other guests in the Astronaut Encounter Theater at the Kennedy Space Center Visitor Complex in Florida. Harris is helping Mercury astronauts, John Glenn and Scott Carpenter, mark the 50th anniversary of Glenn being the first American to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. - Former Mercury astronaut Scott Carpenter, left, and former Kennedy Space Center directors Jay Honeycutt, Bob Crippen, Forrest McCartney and Roy Bridges listen during a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Mercury astronaut Scott Carpenter and his wife, Patricia, pose during a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with John Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA astronaut Stephen Robinson sits at the controls in the flight deck of space shuttle Discovery in Orbiter Processing Facility-1 OPF-1 at NASA's Kennedy Space Center in Florida. Robinson is helping John Glenn mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Robinson was the payload commander of STS-95. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- Mercury astronaut John Glenn, left, talks with fellow Mercury astronaut Scott Carpenter before they ride in the Corvette parade following the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- John Glenn stands in the middeck of space shuttle Discovery in Orbiter Processing Facility-1 OPF-1 at NASA's Kennedy Space Center in Florida. Glenn is at the space center to mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- Mercury astronaut Scott Carpenter, left, prepares to ride in the Corvette parade following the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut John Glenn poses in front of the Mercury 7 memorial near Complex 14 at Cape Canaveral Air Force Station in Florida. Glenn and Carpenter launched from the pad on Atlas rockets inside Mercury capsules in 1962. The two astronauts, part of the original class of seven astronauts chosen by NASA, were taking part in events celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/ Cory Huston

CAPE CANAVERAL, Fla. --Mercury astronaut John Glenn speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut John Glenn, left, and Kennedy Space Center Director Bob Cabana shake hands following the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronauts John Glenn, left and Scott Carpenter look around at the dismantled Complex 14 at Cape Canaveral Air Force Station in Florida. Glenn and Carpenter launched from the pad on Atlas rockets inside Mercury capsules in 1962. The two astronauts, part of the original class of seven astronauts chosen by NASA, were taking part in events celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Cory Huston

CAPE CANAVERAL, Fla. - Former Kennedy Space Center directors Forrest McCartney, from left, Bob Crippen, Jay Honeycutt and Roy Bridges stand with current Kennedy director Bob Cabana, Mercury astronauts John Glenn and Scott Carpenter and NASA Administrator Charles Bolden during a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- John Glenn and NASA astronaut Stephen Robinson stand in the middeck of space shuttle Discovery in Orbiter Processing Facility-1 OPF-1 at NASA's Kennedy Space Center in Florida. Glenn is at the space center to mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Robinson was the payload commander of STS-95. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- John Glenn stands beside the wheel of space shuttle Discovery in Orbiter Processing Facility-1 OPF-1 at NASA's Kennedy Space Center in Florida. Glenn is at the space center to mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. -- John Glenn and his wife, Annie, left, enter Orbiter Processing Facility-1 OPF-1 at NASA's Kennedy Space Center in Florida where space shuttle Discovery is being prepared for public display. Glenn is at the space center to mark the 50th anniversary of being the first American astronaut to orbit the Earth inside the NASA Mercury Project's Friendship 7 capsule on Feb. 20, 1962. Glenn later returned to space in October 1998 as a payload specialist aboard Discovery's STS-95 mission. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Shuttle Discovery currently is being prepared for display at Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. Photo credit: Cory Huston

CAPE CANAVERAL, Fla. --Mercury astronaut Scott Carpenter speaks during the "On Shoulders of Giants" program celebrating 50 years of Americans in orbit, an era which began with John Glenn's MA-6 mission on Feb. 20, 1962. The event was conducted in the Rocket Garden at the Kennedy Space Center Visitor Complex in Florida a few miles from the launch pad where Glenn and Scott Carpenter took flight in Mercury spacecraft. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: Kim Shiflett

CAPE CANAVERAL, Fla. - Mercury astronaut John Glenn and his wife, Annie, pose during a luncheon Feb. 17, 2012, celebrating 50 years of Americans in orbit, an era which began with Glenn's Mercury mission MA-6, on Feb. 20, 1962. Glenn's launch aboard an Atlas rocket took with it the hopes of an entire nation and ushered in a new era of space travel that eventually led to Americans walking on the moon by the end of the 1960s. Glenn soon was followed into orbit by Scott Carpenter, Walter Schirra and Gordon Cooper. Their fellow Mercury astronauts Alan Shepard and Virgil "Gus" Grissom flew earlier suborbital flights. Deke Slayton, a member of NASA's original Mercury 7 astronauts, was grounded by a medical condition until the Apollo-Soyuz Test Project in 1975. Photo credit: NASA/Kim Shiflett