Scott Carpenter, whose flight into space in 1962 as the second American to orbit the Earth was marred by technical glitches and ended with the nation waiting anxiously to see if he had survived a landing far from the target site, died Thursday in Denver. He was 88 and one of the last two surviving astronauts of America’s original space program, Project Mercury.

His wife, Patty Carpenter, announced the death, but no cause was given. He had entered hospice care recently after having a stroke.

His death leaves John Glenn, who flew the first orbital mission on Feb. 20, 1962, and later became a U.S. senator from Ohio, as the last survivor of the Mercury 7.

When Lt. Cmdr. Carpenter splashed down off Puerto Rico in his Aurora 7 capsule on May 24, 1962, after a harrowing mission, he had fulfilled a dream.

“I volunteered for a number of reasons,” he wrote in “We Seven,” a book of reflections by the original astronauts published in 1962. “One of these, quite frankly, was that I thought this was a chance for immortality. Pioneering in space was something I would willingly give my life for.”

For almost an hour after his capsule hit the Caribbean, there were fears that he had, in fact, perished.

He was 250 miles from his intended landing point after making three orbits in a nearly five-hour flight. Although radar and radio signals indicated that his capsule had survived re-entry, it was not immediately clear that he was safe.

A Navy search plane finally spotted him in a bright orange life raft. He remained in it for three hours, accompanied by two frogmen dropped to assist him, before he was picked up by a helicopter and taken to the aircraft carrier Intrepid.

The uncertainty over his fate was only one problem with the flight. The equipment controlling the capsule’s attitude (the way it was pointed) had gone awry. Moreover, he fired his re-entry rockets three seconds late; and they did not carry the anticipated thrust. He also fell behind on his many tasks during the flight’s final moments. His fuel ran low when he inadvertently left two control systems on at the same time.

Some NASA officials found fault with his performance.

“He was completely ignoring our request to check his instruments,” Christopher Kraft, the flight director, wrote in his memoir “Flight: My Life in Mission Control.” “I swore an oath that Scott Carpenter would never again fly in space. He didn’t.”

Carpenter was the fourth American astronaut in space. Alan Shepard and Virgil Grissom flew the first two Mercury flights, and then Glenn orbited the Earth. Carpenter was the fourth man to go into orbit. Two Russians in addition to Glenn had preceded him.

Malcolm Scott Carpenter was born May 1, 1925, in Boulder, Colo.

Carpenter’s first three marriages ended in divorce. Besides his wife, Patty, Carpenter is survived by his sons Jay, Matthew, Nicholas and Zachary; his daughters Kristen Stoever and Candace; a granddaughter, and five stepgrandchildren. Two of his sons, Timothy and Scott, died before him.

Among his many projects, Carpenter joined with fellow astronauts of the original Mercury 7 to create the Astronaut Scholarship Foundation, aiding science and engineering students. In 2006, he returned to the University of Colorado to present a scholarship to a student studying plasma physics.

He used the occasion to reflect on the thrill he experienced. Spaceflights had become “old hat,” he said, but his ardor for space travel remained undimmed.

“The flight experience itself is incredible,” he said. “It’s addictive. It’s transcendent. It is a view of the grand plan of all things that is simply unforgettable.”