here to talk more about this is astronaut ron guerin joining us from houston.'ve repaired that broken pump. how tough is that? you know, you've got 35-year-old space suit to blame for this in a way. what kind of can problems does that is cause? >> well, you know, when we go out on a space walk, our space suits are really self-contained space ships. and there is a lot of moving parts, a lot of things that protect us for one thing but also make our job a little difficult. one of those things is the pressure in the suit itself. everything, every time we grab something with our hand or move we have to fight against the pressure of our suit. and those suits when you put all the tools on it and all the equipment, they could be up to 350 pounds. obviously in space, they're weightless but we're still moving that mass around and still have to deal with that. it really is a very fatiguing, physically fatiguing adventure out there in space when you're on a space walk. >> ron, tell us about that because you've actually had that experience for those of us who couldn't even

joining us, we're happy and fortunate to have the former nasa astronaut ron guerin sharing insight whathappening above the earth. he knows what is involved since he was a spacewalking veteran and the last person to hand the ammonium pump that now has to be replaced. welcome. great to have you here today. >> hi, uma. great to be here. thank you. >> as i understand it, the breakdown forced the astronauts inside the space station to turn off all nonessential equipment to leave scientific research to stand still and leaving the lab in a vulnerable state. is replacing the cooling system a huge undertaking that has only been done once before? >> no, it has been done a couple times before. last time was in 2010, i believe. these are systems on board the space station that have a lifetime associated with them. there is a plan in place to replace them periodically. we have three pump moddums on the space station now as spares. those are put in place to get ready for the situations when they occur. >> until now, as you are obviously aware, spacewalks have been on hold. because of the italian astr

we are joining by colonel ron guerin, a former astronaut with four space walks under his belt.to have you here. you actually handled that pump module that the torontos woastr worked on today. what are they doing here? >> they're switching out this pump which is responsible for a lot of the cooling thattings on the international space station. a lot of equipment both inside and outside the station require cooling. the way we do that on the space station is through ammonia. that ammonia is on the outside of the space station. so we have two redundant systems. the system that failed is on the starboard side of the space station and you know, we have a flow control valve in there that failed. so we have to replace the whole pump module, about 800 pounds. it's a big box basically. >> yeah, as we were talking yesterday, it's weightless in sbas but it is bulky. and you've got to be careful what you're doing. earlier, i know you've been following this. i think we heard them say the connecting the force of four pipes or how does it work? what are they doing now what, are five hours into