Summary:
The last remaining U.S. astronaut, John Glenn, is in "excellent" condition, according to a US historian.

Full article:
(CNN) -- The first American to orbit the Earth has undergone successful heart surgery. Former Sen. John Glenn, 92, had a heart valve replaced last month at the Cleveland Clinic, according to Hank Wilson, director of communications for the John Glenn School of Public Affairs at the Ohio State University. "He's in great shape," and is at home in Columbus, Ohio, recovering, Wilson said. Glenn, piloting the Mercury space capsule dubbed Friendship 7, became the first American to orbit Earth on February 20, 1962, circling the planet three times in just under five hours. He is the last surviving of the original seven U.S. astronauts from Project Mercury. In 1998, at age 77, he flew a nine-day mission aboard the space shuttle Discovery, becoming the oldest person to travel in space. Glenn, a Democrat, served as a U.S. senator from 1974 until 1999, and ran for president in 1984.