Let's get to the breaking news on that major problem onboard the $100 billion international space station, currently home to six astronauts. Abc's john muller has been following developments all night... See More
Let's get to the breaking news on that major problem onboard the $100 billion international space station, currently home to six astronauts. Abc's john muller has been following developments all night for us. Good morning, john. Reporter: Good morning, robin. Nasa says it plans for problems like this. But it doesn't make the situation this morning any less urgent. Engineers at the johnson space center in houston have been working all night to find a fix for the ailing space station. A pump connected to the cooling system, think of it like your car radiator, failed tuesday. Noncritical systems powered down to prevent dangerous overheatin the heat control is a very important aspect of the station. It's not just the temperature for the astronauts. So the instruments don't overheat, the electronics. That could jeopardize the whole station. Reporter: Nasa says for now, six astronauts living on the station, two americans, three russians and one japanese, are not in danger. It's a pretty good setup here. Reporter: Engineers have two options. A software upgrade. Or if that doesn't work, a riskier, emergency spacewalk. Nasa suspended spacewalks in july. My helmet is wet. And I'm feeling freezing. Reporter: The space station had a similar problem a few years ago. The astronaut who helped solve that crisis, now working with the team in houston, looking for answers as we speak. If a second cooling system fails, astronauts may have to evacuate. We could find out later today if a spacewalk is necessary. We're hearing from the infamous imposter at nelson
This transcript has been automatically generated and may not be 100% accurate.