As the slugfest for dominance in space raged on between American astronauts and Soviet cosmonauts in the mid-1960s, the U.S.S.R. scored a big first 35 years ago when Alexei Leonov exited the airlock of the Voskhod 2 spacecraft.

Hardly knowing what to expect, Leonov became the first human to ever walk in the vacuum of space as he braved 10 minutes outside the Voskhod 2 while his crewmate Pavel Belyayev anxiously waited inside the craft on March 18, 1965.

Over the years, Leonov's adventure in space has become a legend, retold numerous times and shrouded in myth. In recent years, several Russian-language sources have revealed many previously unknown facts about the mission, while also posing more questions for historians.

Korolev knew about the Gemini spacecraft being developed in the U.S. at the time, which would allow the crew to depressurize the ship and work outside the craft.

But Korolev rejected the idea of depressurizing the craft. Instead he ordered his engineers to find a way to fit a special airlock into the design of the Voskhod spacecraft.

Several designs for the airlock emerged -- some rigid, some flexible and some that could be rolled into a spiral before launch. According to corporate history of RKK Energia, their company's engineer proposed a winning design code-named Volga. (RKK Energia is the company that provides much of the Russian space agency's hardware.)

Finally a cylindrical airlock design was agreed upon, one that would be comprised of 36 inflatable booms isolated in three groups of 12. Even if two groups of booms lost pressure, the lock would retain its shape, designers believed.

In an interview on Friday with SPACE.com, Leonov said his mission was approved in February 1964. Around March 1964, a mockup of the craft designed for a spacewalk was shown to a group of 20 original cosmonauts, including Leonov. (Leonov currently is on SPACE.com's board of directors)

"The sailor on the ship should be able to swim," Leonov remembers Korolev saying to the young cosmonauts. He told Leonov to put on a spacesuit and attempt a simulated spacewalk.

According to plans, the spacewalking cosmonaut would be attached to the spacecraft via an umbilical cord. The cord would supply him with oxygen and provide communication with the commander and ground control. A backpack would contain an emergency oxygen supply.

Both cosmonauts would wear spacesuits inside the spacecraft. In case of an emergency during the spacewalk, such as unconsciousness, the commander could depressurize the ship, go outside and save his colleague. The commander would have to reattach the umbilical cord to his disabled colleague's shoulders and pull him into the airlock headfirst.

All the emergency modes were tested in ground training and in simulated weightlessness on board the Tupolev 104 flying lab.

Voskhod 2 successfully reached orbit on March 18, 1965. The crew almost immediately started preparing for the spacewalk. Commander Belyaev helped Leonov don his emergency pack and attach the umbilical cord.

Leonov successfully depressurized the airlock and left the spacecraft. "I felt good and reported what I saw," Leonov said.

However, about 10 minutes into the walk Leonov noticed trouble.

"The spacesuit started behaving absolutely different from what it did on the ground," Leonov said.

The suit ballooned up, constricting his movements and forcing his hands and feet out of the gloves and boots. By the time Leonov was ready to reenter the spacecraft things got out of hand.

"Despite a tight fit, my feet got out of [the suit's] boots and [my] hands out of [the] gloves, Leonov remembers. "The work became impossible, I tried to grab the handles [on the airlock] and my fingers wouldn't workthe gloves' fingers would just bend on me."

The situation also was complicated by the fact that Leonov was holding a camera he had removed from the edge of the airlock.

At this point Leonov, without consulting with ground control, decided to use a special valve to drop the pressure inside the suit by almost 200 percent. "I decided I was breathing oxygen long enough to prevent boiling nitrogen in the blood (decompression sickness)," he said. "There was some risk, but I had nothing else to do, and once I did, everything started going normal."

"I did not ask the ground about it. I figured, I don't have time for that. I could just imagine all their discussions [about what to do]," Leonov said. "It would be me who had to do it anyway."

Upon finally entering the airlock head first, Leonov encountered another problem: How to turn "upright" to close the hatch of the airlock behind him. The airlock was around 4 feet (120 centimeters) in diameter, while Leonov's height in the spacesuit was around 6 feet (190 centimeters).

"I literally had to fold myself, to do this," Leonov said, "I spent tremendous effort trying to do this, I had a total of 60 liters [of air] for ventilation and breathing, which was not enough for this kind of action."

Leonov's spacesuit filled with sweat, almost up to his ankles.

Finally, the cosmonaut closed the hatch, pressurized the airlock and rejoined Belyayev.

Leonov dismissed reports that he had suicide pills with him in case he couldn't reenter the spacecraft, calling such claims "hallucinations".

Leonov's successful return into the spacecraft did not end the mission's troubles.

After the crew jettisoned the airlock, pyrotechnic gas apparently disabled the sun sensor designed to allow Voskhod 2 to orient itself for a reentry maneuver.

As a result, the spacecraft began tumbling in space, and five minutes before the scheduled reentry maneuver, the crew shutdown the system.

Reentry was achieved after the crew performed an orientation maneuver manually on a second opportunity. However, the new landing site was now hundreds of miles from the planned drop-down area.

The spacecraft's instrument module was supposed to jettison automatically 10 seconds after the reentry firing but failed to do so. Fortunately, a backup option worked as designed. Temperature sensors sent a separation signal when the spacecraft experienced the initial heat of reentry.

The spacecraft landed in the snow-covered taiga, and the first help came in the form of the timber workers who arrived 24 hours later.

Since specially equipped helicopters were stationed only at the primary landing site, Leonov and Belyayev had to spend three days in the forest before enough trees were cut for the helicopters to land.

After analyzing the Voskhod 2 reentry capsule, engineers reported to Korolev that the spacecraft's parachute had been jettisoned by a signal from a special probe when it touched the ground. The device had been introduced after a recent test flight to prevent the capsule from being dragged by the wind.

If the probe had grazed treetops during the Voskhod 2 landing, it would certainly have detached the chute leaving the capsule and crew to free-fall.

Legend has it that when Korolev realized that the cosmonauts were almost killed, he said, "I am the king and the god saves me."

Korolev means "king" in Russian.