John Glenn was not popular with the other astronauts. Glenn was the backup pilot for Shepard and Grissom on the first two manned Project Mercury flights, the sub-orbital missions Mercury-Redstone 3 and Mercury-Redstone 4. Glenn was selected for Mercury-Atlas 6, NASA's first manned orbital flight, with Carpenter as his backup. Putting a man in orbit would achieve one of Project Mercury's most important goals. Shepard and Grissom had named their spacecraft "Freedom 7" and "Liberty Bell 7". The numeral 7 had originally been the production number of Shepard's spacecraft, but had come to represent the Mercury 7. Glenn named his spacecraft, number
John Glenn offer, and that Zwicharowski's actions were improper. No administrative action was taken as he had retired. President Barack Obama said that John Glenn, "the first American to orbit the Earth, reminded us that with courage and a spirit of discovery there's no limit to the heights we can reach together". Tributes were also paid by President-elect Donald Trump, and former Secretary of State Hillary Clinton. The phrase "Godspeed, John Glenn", which fellow Mercury astronaut Scott Carpenter used to hail Glenn's launch into space, became his social-media hashtag: #GodspeedJohnGlenn. Former and current astronauts added tributes; so did NASA Administrator and former