"He's back," exulted the Miami News when John Glenn emerged from Friendship 7 after orbiting the Earth three times.

America, the Miami Herald implied, was back, as well. The Frankfurter Allgemeine Zeitung agreed: The free world need "no longer stare as if hypnotized at Soviet space successes with pricks of doubt in their hearts as to whether there is not some deep deficiency in the democratic order."

In "Mercury Rising," Jeff Shesol, a former speechwriter for President Bill Clinton and author of "Supreme Power: Franklin Roosevelt vs. the Supreme Court," provides a splendid account of Glenn's mission. Shesol sets America's space program in the context of the Cold War. Drawing on interviews and Glenn's personal notes, he includes a fascinating portrait of the astronaut who became a national icon.

President Dwight Eisenhower, Shesol reveals, believed that a manned space program was not all that important, either scientifically or militarily. Shortly before he left office, Eisenhower declared, "he couldn't care less whether a man ever reached the moon" and was not going "to hock the family jewels" to fund it.

John Kennedy tended to agree. But when Russian cosmonaut Yuri Gagarin orbited the Earth in April 1961, space took center stage. As the Cold War heated up — over the Bay of Pigs fiasco, Russia's nuclear tests and construction of a Berlin Wall — the young president concluded that to be second in space was to be second in the existential struggle between communism and freedom.

In May 1961, Kennedy declared that the nation should commit itself to landing a man on the moon by the end of the decade.

Glenn's flight on Feb. 20, 1962, was a giant step in restoring America's preeminence in space. Glenn, Shesol demonstrates, was the man for this moment. A Korean War Marine fighter pilot, he had a 1950s sensibility: He believed in God, country and fidelity to his marriage vows. Charming and articulate, Glenn was an ideal spokesman for NASA.

Glenn's outsized ambition, Shesol suggests, was less visible to most Americans. Professional colleagues branded him a "sniveler," who got what he wanted even if he "wasn't slated to get it." To "sit back and let fate play its hand out and never try to influence at all," Glenn agreed, "is not the way man was made to operate."

Glenn campaigned hard to be chosen for the Friendship 7 spaceflight. He fought NASA administrators who left little or nothing to astronauts' discretion, an approach that angered Glenn when he learned how perilous his re-entry to Earth had been.

Too old to be considered for the Apollo moon flight, Glenn drifted into politics. He served four terms as United States senator from Ohio. But spaceflight remained his passion. Glenn campaigned hard to be sent back into orbit, and in 1998 got his wish: a nine-day mission on the Discovery space shuttle. That's where Shesol leaves him — slipping free of his restraints, floating up to the flight deck, "looking at the Earth below, its blues as brilliant as memory held."

Glenn C. Altschuler is the Thomas and Dorothy Litwin Professor of American Studies at Cornell University.

Mercury Rising

By: Jeff Shesol.

Publisher: W.W. Norton, 400 pages, $28.95.