systems on the international space station. it malfunctioned this week. the pump on the cooling loop automatically shut down. that system makes sure equipment on iss stays cool and keeps working. nasa officials said yesterday they tried one fix that didn't work, and they may have to do a space walk to replace it. i am joined now by michael nasamino, a nasa astronaut and visiting professor at columbia university engineering school. mike, it's a pleasure and honor to have you on the program. tell me this. >> thanks for having me. >> from the scale of things that can go wrong in a space station, where does this rank in severity and concern? >> i would say probably somewhere in the middle. it's not a really bad thing. there are plenty of things that can happen to you that are a lot worse, but it's also not a very good thing. as you explained, we have two cooling loops, one is down. luckily, we have the second one to keep everything working correctly, so no one is in any danger. science can still continue, but