CAPE CANAVERAL, Fla. -- Mercury astronaut John Glenn, left, and NASA Administrator Charles Bolden share a laugh during the "50 Years of Americans in Orbit" presentation for employees at NASA's Kennedy Space Center in Florida. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA Administrator Charles Bolden, right, listens as Mercury astronaut John Glenn speaks to employees during the "50 Years of Americans in Orbit" presentation at NASA's Kennedy Space Center in Florida. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Annie Glenn, right, wife of Mercury astronaut John Glenn, and their children listen during the "50 Years of Americans in Orbit" presentation for employees at NASA's Kennedy Space Center in Florida. John Glenn and fellow Mercury astronaut Scott Carpenter were joined by NASA Administrator Charles Bolden and Center Director Bob Cabana on stage in Kennedy's training auditorium. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut Scott Carpenter's wife, Patricia Carpenter, left, and children listen during the "50 Years of Americans in Orbit" presentation for employees at NASA's Kennedy Space Center in Florida. John Glenn and fellow Mercury astronaut Scott Carpenter were joined by NASA Administrator Charles Bolden and Center Director Bob Cabana on stage in Kennedy's training auditorium. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA Administrator Charles Bolden, Mercury astronauts Scott Carpenter and John Glenn, and Bob Cabana, director of NASA's Kennedy Space Center in Florida, stand for applause at the conclusion of the "50 Years of Americans in Orbit" presentation for Kennedy employees. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Bob Cabana, director of NASA's Kennedy Space Center in Florida, shakes the hand of Mercury astronaut Scott Carpenter at the "50 Years of Americans in Orbit" presentation for Kennedy employees. Mercury astronaut John Glenn and NASA Administrator Charles Bolden joined Carpenter and Cabana for the event. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Employees at NASA's Kennedy Space Center in Florida listen as Center Director Bob Cabana, Mercury astronauts Scott Carpenter and John Glenn, and NASA Administrator Charles Bolden share their spaceflight memories during the "50 Years of Americans in Orbit" presentation for employees. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Bob Cabana, director of NASA's Kennedy Space Center in Florida, shakes the hand of Mercury astronaut John Glenn as NASA Administrator Charles Bolden applauds at the "50 Years of Americans in Orbit" presentation for Kennedy employees. Mercury astronaut Scott Carpenter joined Glenn, Bolden and Cabana for the event. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- It's "standing room only" in the training auditorium at NASA's Kennedy Space Center in Florida, where Mercury astronauts John Glenn and Scott Carpenter were joined by NASA Administrator Charles Bolden and Center Director Bob Cabana for the "50 Years of Americans in Orbit" presentation for employees. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronauts Scott Carpenter and John Glenn shake hands with NASA Administrator Charles Bolden right and Bob Cabana, director of NASA's Kennedy Space Center in Florida left at the conclusion of the "50 Years of Americans in Orbit" presentation for Kennedy employees. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Employees at NASA's Kennedy Space Center in Florida listen as Center Director Bob Cabana, Mercury astronauts Scott Carpenter and John Glenn, and NASA Administrator Charles Bolden share their spaceflight memories during the "50 Years of Americans in Orbit" presentation for employees. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- From left to right, Center Director Bob Cabana, Mercury astronauts Scott Carpenter and John Glenn, and NASA Administrator Charles Bolden share the stage during the "50 Years of Americans in Orbit" presentation for employees at NASA's Kennedy Space Center in Florida. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronaut Scott Carpenter talks to Bob Cabana, director of NASA's Kennedy Space Center in Florida, during the "50 Years of Americans in Orbit" presentation for employees at NASA's Kennedy Space Center in Florida. Mercury astronaut John Glenn and NASA Administrator Charles Bolden joined Carpenter and Cabana for the event. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Mercury astronauts Scott Carpenter and John Glenn pause for a handshake at the conclusion of the "50 Years of Americans in Orbit" presentation for employees at NASA's Kennedy Space Center in Florida. NASA Administrator Charles Bolden and Center Director Bob Cabana joined Carpenter and Glenn for the event. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Bob Cabana, director of NASA's Kennedy Space Center in Florida, and Mercury astronaut Scott Carpenter share the stage during the "50 Years of Americans in Orbit" presentation for employees at NASA's Kennedy Space Center in Florida. Mercury astronaut John Glenn and NASA Administrator Charles Bolden joined Carpenter and Cabana for the event. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett