Accidental hero

John Glenn enters the capsule that propelled him into orbit

John Glenn was never meant to be the first American to orbit the Earth.

Embroiled in a frantic space race with the Soviet Union, Nasa cancelled the last of three 15-minute Mercury there-and-back space hops and in February 1962 decided to go for the big one - orbital flight.

Preparing for an historic flight

Glenn was supposed to make an anonymous sub-orbital hop, but after Soviet rivals sent Captain Gherman Titov into orbit for more than a day in Vostok 2, the USA was under political pressure to exceed this record.

They had already had to watch the Soviets crow over their hero Yuri Gagarin who became the first man to go into space on April 12, 1961 in the Vostok 1 space craft.

Less than a month after Gagarin's flight Alan Shepard became the first American in space for just 15 minutes with his Freedom 7 Mercury capsule. Two months later Gus Grissom made a similar flight.

Although the Mercury spacecraft was more sophisticated than Vostok, the Soviets had more powerful rockets.

The Americans caught up with the new Atlas rocket.

The new Atlas rocket made the journey more comfortable

Glenn was the first to be sent up on this more powerful, controllable and ultimately more comfortable form of propulsion. Instead of the almost unbearable 11 Gs experienced by previous Mercury astronauts, Glenn was subjected to 7 Gs - not much more than a modern rollercoaster ride.

'Feeling good'

At an altitude of 98 miles the Atlas rocket automatically propelled the capsule, Friendship 7, into orbit. The Mission Control log read: "9:52. We are through the gates."

"Zero-G and I feel fine," Glenn radioed back. "Capsule is turning around. The view is tremendous, it is beautiful, a beautiful sight."

Earth from Friendship 7: 'A beautiful sight'

On weightlessness, he said, "I have nothing but a fine feeling. It feels very normal and very good."

The flight did not go completely smoothly. He had to take over manual control of the capsule following a nagging problem with a thruster.

Then there was a problem that could have killed him.

Unknown to ground controllers a sensor was faulty indicating that the heat shield was not secured to the capsule securely.

After much consultation it was decided to keep his retro-pack on during re-entry. This was positioned over the heat shield and if it was left in place would hold the heat shield down.

Glenn was not told about this but soon realised the position.

Narrow miss with disaster

After three orbits when he was over the Pacific, the Mercury capsules retro-rockets were fired. This was the most hazardous part of the mission. Glenn's pulse rate rose to 132 beats a minute.

Glenn: dangerous mission

The next few minutes could be his last. Later he was to say that if the heat shield had failed, "It would have been a bad day all round."

During re-entry radio communication was impossible due to the hot ionised gasses around the capsule but then Glenn's voice, tinged with tension, was heard through the static.

"This is Friendship 7. A real fireball outside. My condition is good but that was a real fireball - boy! I had chunks of that retro-pack breaking off all the way through."

The re-entry drama was not over yet. After the fireball the capsule started oscillating wildly, "I felt like a falling leaf," he said.

Then his fuel ran out and he decided to deploy the first parachute manually but as he moved his hand towards the lever it deployed on its own.

From then on his splashdown went normally except for becoming uncomfortably hot in the capsule after it was winched aboard the waiting aircraft carrier. He told the sailors standing next to the capsule to stand back and then blew the explosive bolts to jettison the hatch.

A few moments later he emerged, hot and exhausted, but elated. President Kennedy was on the phone.

With his orbital flight the USA had regained some ground in the space race.

Space hero honoured by President Kennedy

Glenn became a national hero, the most famous of the Mercury 7 astronauts. Like Yuri Gagarin he became a weapon in the Cold War propaganda machine and therefore too precious an asset to fly.

With sadness he watched his colleagues preparing for missions to the Moon and knew that, for the foreseeable future at least, he would not go back into space.

After Glenn's mission there were 2 more Mercury flights and then project Gemini.

The Gemini spacecraft was larger and more sophisticated than the Mercury capsule and could take two men into space. It could carry out rendezvous and docking which were essential for a mission to the Moon.