Name: How Astronauts Avoided Disaster Building the International Space Station
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Astronauts faced a life-threatening challenge during construction of the International Space Station.

A dangerous spacewalk, a toxic leak, and a breathtaking view of Earth.

How Astronauts Avoided Disaster Building the International Space Station

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Astronauts faced a life-threatening challenge during construction of the International Space Station.

A dangerous spacewalk, a toxic leak, and a breathtaking view of Earth.

Space & Flight

How Astronauts Avoided Disaster Building the International Space StationPublished: December 9, 2025NARRATOR: 250 miles above the surface of the earth, astronauts Tom Jones and Robert Beamer Curbeam prepare for an extra vehicular activity. A spacewalk. 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.ROBERT CURBEAM: Getting a lot of ice. Cutting bony all over the place.NARRATOR: Years of training mean Beamer remains calm, but it's a serious problem.TOM JONES: Need a hand, Beam?ROBERT CURBEAM: Yeah, I am going to need one.TOM JONES: 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.ROBERT CURBEAM: I did find very quickly that it was going to be a lot harder than I thought.NARRATOR: The valve is stuck.ROBERT CURBEAM: When I tried to close it didn't close. I tried again, it didn't close. They said it was going to be about 25 lbs of force. I've spent a lot of time in the gym. It was not 25 lbs 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.TOM JONES: Just pulled the bail?ROBERT CURBEAM: Yeah. And that stopped the leak.TOM JONES: 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.TOM JONES: And sooner or later he's got to come back in the cabin and expose the outside of the suit to his crewmates who are not interested in dying horrible deaths.ROBERT CURBEAM: I thought to myself, "What are they going to do with me, now that I have this toxin on the outside of the suit?" I knew that the procedure to go back into the spacecraft was going to change. I just didn't know how.NARRATOR: Tom wipes the toxic crystals off his crewmate'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.ROBERT CURBEAM: The amazing thing about the procedure to help me decontaminate the outside of my space suit, 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. 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.

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How Astronauts Avoided Disaster Building the International Space Station

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Support Provided By

Explore More

Operation Space Station: Science and Survival

Operation Space Station: High-Risk Build

Decoding the Universe: Cosmos