After their second marathon space walk in five days, astronauts on board the International Space Station are one small but significant step closer to resolving their troubles with a faulty ammonia pump. Spacewalkers Tracy Caldwell Dyson and Douglas Wheelock managed to remove the 350-kilogram pump from the station’s starboard (S1) truss – a goal that eluded them on August 7. They will try to install a replacement unit during a third spacewalk, scheduled for 16 August.

The pump, which broke down on 31 July, is part of the station’s cooling system. It circulates liquid ammonia through a series of lines that draw excess heat away from the interior of the station and transfer it to the station’s external radiators.

Today’s successful effort and continuing emergency maneuvers related to the failed pump have come at some cost to the station’s scientific program. NASA says that most research has been impacted, though not to a significant degree.

ProK and VO2max – two research efforts monitoring the effects of long-term spaceflight on human health – had to skip a few data collection intervals while the astronauts’ priorities were elsewhere. Additionally, several experimental robots named SPHERES have been neglected during the repair tussle. Astronauts also had to postpone a video conference with middle schoolers.

And if you were wondering whether the Perseid meteor shower, now nearing its peak, presents any danger to the astronauts when they venture outside the space station: don’t worry. NASA officials say the shower only boosts the quantity of dust-sized particles speeding past the station by about 15%, deemed an acceptable increase in risk.

Image: NASA TV