- [Narrator] 250 miles above the surface of the earth, astronauts Tom Jones and Robert "Beamer" Curbeam, prepare for an extra vehicular activity, a spacewalk.

(mellow music) Just over two years into construction of the International Space Station, the structure is far from complete.

The space shuttle, Atlantis, has brought up a new component, the laboratory module, Destiny.

Tom and Beamer need to connect vital life support systems to enable astronauts to live and work in the lab.

They are working in a lethally dangerous environment and suddenly, something goes wrong.

A coolant valve fails, spewing toxic ammonia crystals into the vacuum of space.

- Getting a lot of ice.

There's ammonia all over the place.

- [Narrator] Years of training, mean Beamer remains calm, but it's a serious problem.

- Need a hand, Beam?

- Yeah, I am gonna need one.

- We don't know exactly what the leak rate was, but I knew we didn't have long.

- [Narrator] Beamer needs to find the shutoff valve upstream and turn it off.

- I did find, very quickly, that it was gonna be a lot harder than I thought.

- [Narrator] The valve is stuck.

- When I tried to close it, it didn't close.

I tried again, it didn't close.

They said it was gonna be about 25 pounds of force.

I've spent a lot of time in the gym, it was not 25 pounds of force.

It was much, much more.

I tried to close it again, and finally, after four or five tries, I got to close it.

(tense music) - You just pulled the bail?

- Yeah.

And that stopped the leak.

- Very good, Beam.

Good idea.

- [Narrator] Mission control breathes a sigh of relief.

With the leak stopped, the astronauts can connect Destiny's cooling lines to the station.

The ISS is safe, but now Beamer is covered in toxic ammonia.

- And sooner or later, he's gotta come back in the cabin and expose the outside of the suit to his crew mates who were not interested in dying horrible deaths.

- I thought to myself, what are they gonna do with me, you know, now that I have this toxin on the outside of the suit.

I knew that the procedure to go back into the spacecraft was gonna change.

I just didn't know how.

- [Narrator] Tom wipes the toxic crystals off his crew mate's spacesuit using a brush in their EVA kit.

But before he can reenter the space station, Beamer must burn the last remaining traces of ammonia off his suit in the baking heat of the sun.

(gentle music) - The amazing thing about the procedure to help me decontaminate the outside of my spacesuit was that it gave me the opportunity to just sit in the sun and watch the earth go by for 45 minutes, which was awesome and it was incredible.

I loved it.

(gentle music) And you see the Gobi Desert, you see all the different parts of Asia.

You see the Himalayas to the south, you see a little bit of cloud layer there and you just bask in it.

(gentle music)