[NARRATOR:] In the spring of 1959,
the National Aeronautics and Space Association, NASA,
introduced Americans to a new kind of hero --
the astronaut.
Known as the Mercury 7,
their mission was to rocket beyond the earth's atmosphere,
and they quickly became a national sensation.
In the months that followed their faces blanketed the news,
as the country waited to see who would become the first man in space.
But far from the Project Mercury spotlight,
deep in the New Mexico desert,
the Air Force was also preparing to launch a man towards the heavens.
With a fraction of NASA's budget and none of its renown,
Project Excelsior was about to send Captain Joseph Kittinger
100,000 feet above the Earth,
and he would get there not by rocket,
but by balloon.
It was the culmination of over a decade of little-known aerospace experiments,
and this would be the most dangerous of them all.
[Craig RYAN, Writer:] There were a myriad of problems with sending a person up to that altitude.
Could you keep them warm?
Would they be exposed to dangerous radiation?
How do you give them a safe breathable atmosphere?
[Burkhard BILGER, Writer:] Above 60,000 feet, you've got so little pressure that your blood can boil.
Organs can rupture, blood vessels can rupture.
The temperature is a hundred degrees below zero.
There are just so many things that can go wrong.
[Gregory KENNEDY, Aerospace Historian:] At 100,000 feet you're above 99 percent of the earth's atmosphere,
so you might as well be in space.
Narrator: Though largely forgotten,
balloonists would be the first to venture into the frozen vacuum on the edge of our world,
exploring the very limits of human physiology and human ingenuity in this deadly realm.
[Ken HOLLINGS, Writer:] Flying in a balloon to the upper reaches of the atmosphere,
perhaps seems odd, eccentric,
even self-inflicted madness.
But there's no question that these experiments fed into what NASA was about to undertake with Mercury.
They answered a lot of questions.
They answered a lot of big questions.
[RYAN:] At 102,800 feet,
higher than any human being has ever been in a balloon at this point,
Joe Kittinger gets a signal from his ground
crew.
He stands up in the gondola,
disconnects his onboard oxygen supply,
says a little prayer,
and steps off.
[NARRATOR:] In April 1947,
a young army doctor was transferred to a remote airfield 100 miles north of Los Angeles,
soon to be named Edwards Air Force Base.
John Paul Stapp was a maverick in the burgeoning field of aviation medicine
and Edwards was just the place to be.
Only months after Stapp's arrival,
test pilot, Chuck Yeager, broke the sound barrier in the rocket-powered X-1.
His accomplishment marked the beginning of a new era
that would push the limits of man and machine.
[HOLLINGS:] Aerospace as a concept,
the idea of getting a man high up into the atmosphere and beyond,
was still relatively new.
And doctors were aware that the human body,
although robust and neatly packaged,
does have its limits.
[Francis FRENCH, Aerospace Historian:] John Stapp was watching jets go higher and faster
and realized that scientists and doctors had no idea really
what would happen to the human body
as it was subjected to faster forces and higher altitudes than ever before.
[BILGER:] And so Stapp decides to investigate what the human body can handle.
How much speed we can handle,
how much falling we can handle,
how much altitude we can handle.
And he starts to unpack this little by little.
[NARRATOR:] Stapp explored pilot ejection seats,
liquid oxygen breathing systems,
tested the impact of windblast,
and subjected a succession of Air Force personnel to all manner of experimental contortions.
But he spent the most time studying G-force limits:
how the intense acceleration and deceleration,
encountered in a rocket or high-speed jet,
affected the human body.
The military maintained that any force beyond 18Gs --
or 18 times the pull of gravity --
would be fatal.
Stapp helped design a series of faster and faster rocket sleds,
to challenge that assumption.
Imagine a soapbox racer made of aluminum on a railroad track
with rockets on the back of it.
Which would be fired down the track
and then slammed to a stop in just a few seconds.
[NARRATOR:] Stapp rode the sleds himself,
each time ramping up the speed and the G-force pressing on his body.
He cracked ribs, lost six fillings and broke both of his wrists.
"I prefer to take the physical punishment personally," he told one observer,
"rather than risk the court-martial for killing some unlucky sergeant."
He got up to over 300 miles an hour and pulled 38 Gs.
And when he told his superiors that he had survived 38 Gs
they told him to cease and desist immediately.
[RYAN:] Stapp used to say, "I always follow orders when they make sense."
And he always pushed it a little farther than his superiors were comfortable with.
[NARRATOR:] On December 10th, 1954, Stapp took his experiment to it's extreme.
[RYAN:] There were nine rocket engines on the back of that sled.
And when they fired, Stapp said that he lost all orientation
as he shot down this track in excess of 630 miles per hour.
At the end of the track, Stapp slammed to a full stop in 1.35 seconds.
[KENNEDY:] It was the equivalent to ejecting from an airplane at 30,000 feet.
And he was out to prove that a pilot could do that in an ejection seat and survive.
[KILANOWSKI:] The most serious thing that happened was the hemorrhaging into his retinas.
He got out of the rocket sled, he thought he was permanently blind.
[KENNEDY:] He was taken to the base hospital where gradually his vision came back.
He had two black eyes,
but other than that, he was fine.
[NARRATOR:] John Paul Stapp had set an almost inconceivable G-force record of 46.2
and was heralded as "The Fastest Man on Earth."
