In this photo provided by NASA, Sen. John Glenn poses for a portrait shortly after doing live television interviews from the Ohio State University Union building, Monday, Feb. 20, 2012, in Columbus, Ohio. Monday marks the 50th anniversary of Glenn's historic flight. Glenn was the first American to orbit Earth. (AP Photo/NASA, Bill Ingalls) MANDATORY CREDIT

(AP) -- John Glenn plans to mark the 50th anniversary of his historic spaceflight with a series of events Monday at Ohio State University, including a celebratory dinner and a chat with the International Space Station.

The astronaut and senator from Ohio became the first American to orbit the Earth on Feb. 20, 1962, circling it three times in five hours and helping to lead the nation into space. The trip helped the United States catch up to the Soviet Union's accomplishments, and Glenn said he thinks it was a turning point for the national psyche.

"It's amazing to me to look back 50 years and think that it's been 50 years," Glenn told The Associated Press last month.

He and Charles Bolden were expected to speak with the space station on Monday to kick off a NASA forum about the agency's future and its role in advancing fields such as science, technology and the economy. Glenn and Annie, his wife of almost seven decades, will cap the day by participating in a student-led question-and-answer session during an evening gala featuring a keynote speech by former astronaut , the commander of the space shuttle Endeavour's final mission.

Glenn was among the top military test pilots presented in 1959 as the Mercury Seven. The only other surviving Mercury astronaut is Scott Carpenter, who called out the memorable line "Godspeed John Glenn" moments before the rocket ignited for Glenn's spaceflight.

The trip is among the accomplishments that made Glenn, as Ohio State President E. Gordon Gee put it, one of the country's "greatest treasures."

"John Glenn is, quite simply, an extraordinary American patriot," Gee said in a statement ahead of the event. "He is a man of boundless courage, limitless optimism and unswerving honor. I am deeply grateful for this opportunity to celebrate his tremendous achievements and his important leadership at Ohio State."

In 1998, when he was 77, Glenn became the oldest person to fly in space.

Now 90, Glenn is the namesake of a NASA research center in Cleveland and a public affairs school at Ohio State. He's given the university more than a thousand boxloads of materials and artifacts to display, including the hand controller with which he flew the Friendship 7 capsule on that historic orbit 50 years ago.