Big Machines like the Space Station can break!

Like any big machine, the huge International Space Station requires daily maintenance repairs to keep flying in space. But every now and then something big or critical – like the recent cooling system trouble – pops up to shine a spotlight on the $100 billion space station, which has been continuously manned by astronauts for nearly 10 years.

Half of the space station's cooling system shut down late Saturday when a circuit breaker tripped in a pump used to move super-cold liquid ammonia through the system. Now astronauts living aboard the station are planning two emergency spacewalks, currently set for Thursday and Sunday, to replace the pump in the afflicted cooling system line – called Loop A.

But while astronauts regularly work through smaller glitches on the space station, critical or serious malfunctions are relatively rare. The space station has been under construction since 1998. It is currently home to six people and has a main truss as long as a football field.

Ads by Google Satellite earth Free Satellite earth All The Time With The Maps Toolbar Maps.alot.com Coffee Fool Banned Grocery stores won't stock us because we're the truth on fresh! www.CoffeeFool.com

Here's a look, by no means comprehensive, at some recent notable malfunctions during the space station's 10 years in orbit:

Russian docking system glitch

The most recent notable glitch at the space station occurred in early July, when an unmanned Russian cargo ship sailed completely past the International Space Station instead of docking at the outpost as planned.

The Progress 38 cargo ship was flying on autopilot as designed on July 2 when it unexpectedly aborted the docking attempt and missed the space station.  Russian engineers suspect interference between the spacecraft's Kurs automated docking system and a space station system that allows cosmonauts to take remote control of the Progress spacecraft caused the abort.

The solution? Simply turn off the remote control system on the space station. The station crew did that and on July 4 the Progress 38 parked itself at the orbiting lab as planned.

Cooling system valve woes

The space station's Loop A cooling system has seen some glitches before.  In April, a stuck valve sent NASA engineers scrambling to come up with a fix while the space shuttle Discovery was docked at the orbiting lab.

At the time, NASA engineers were considering an emergency spacewalk to either fix or replace the faulty Loop A valve. The valve controlled the flow of nitrogen, which is used to pressurize the cooling system plumbing ahead of the liquid ammonia flow.

Engineers didn't immediately fix the valve, but after studying the space malfunction exhaustively they did decide the glitch didn't pose an immediate problem. The crew of Endeavour did not have to perform an extra spacewalk and were able to depart the space station in mid-April as planned.

READ MORE: Space.com