50 years since first U.S. orbit Sen. John Glenn talks, via satellite, with the astronauts on the International Space Station, before the s...

50 years since first U.S. orbit

Sen. John Glenn talks, via satellite, with the astronauts on the International Space Station, before the start of a roundtable discussion titled "Learning from the Past to Innovate for the Future" Monday, Feb. 20, 2012, in Columbus, Ohio. (AP Photo/Jay LaPrete)

Former astronaut and U.S. Senator John Glenn (L) makes NASA Administrator Charles Bolden laugh, when he said his wife Annie asked him not to go on the flight 50 years ago, during a news conference at The Ohio State University in Columbus, Ohio February 20, 2012. (REUTERS/Mike Munden)

The International Space Station crew (L-R) John Pettit, Andre Kuipers and Dan Burbank are seen in this still photograph taken of a television screen as they speak live with former astronaut and U.S. Senator John Glenn and NASA Administrator Charles Bolden during the agency's two-day Future Forum at The Ohio State University in Columbus, Ohio February 20, 2012. (REUTERS/Mike Munden)

Sen. John Glenn, left, and Charles Bolden, administrator from NASA headquarters, talk, via satellite, with the astronauts on the International Space Station, before the start of a roundtable discussion titled "Learning from the Past to Innovate for the Future" Monday, Feb. 20, 2012, in Columbus, Ohio. (AP Photo/Jay LaPrete)

Former Sen. John Glenn, left, and Scott Carpenter, right, speak at the Kennedy Space Center, Friday, Feb. 17, 2012 in Cape Canaveral, Fla. John Glenn fever has taken hold in the U.S. once again. (AP Photo/Michael Brown)

Astronaut John Glenn, on Feb. 20 marking the 50th anniversary of his historic flight as the first American to orbit the Earth, remembered it as the best day of his life.

(Agencies)