"Houston we have a problem" - Space station leaking vital coolant, NASA says.

"Houston we have a problem" - Space station leaking vital coolant, NASA says.(NBC).By Clara Moskowitz.Astronauts on the International Space Station have discovered a leak of ammonia coolant on their orbiting habitat, and NASA is looking into the problem, though it poses no immediate danger to the crew, officials said Thursday.

The space station uses chilled liquid ammonia to cool down the power systems on its eight giant solar array panels. A minor leak of this ammonia was first noticed in 2007, and NASA has been studying the issue ever since. In November 2012 two astronauts took a spacewalk to fix the problem, rewiring some coolant lines and installing a spare radiator due to fears the original radiator was damaged by a micrometeorite impact.

Today astronauts on the football field-size space station noticed a steady stream of frozen ammonia flakes leaking from the area of the suspect coolant loop in the Photovoltaic Thermal Control System (PVTCS).

Humphries of the Johnson Space Center in Houston told Space.com. Humphries said the agency was taking the leak seriously because it affects an important system — if they loose the ability to cool that particular solar array, it won't be able to generate power for the station. In fact, the leak has worsened to the point that Mission Control expects that particular loop to shut down within the next 24 hours.

However, "the crew is in no danger," Humphries stressed. It's too soon to speculate on a possible spacewalk or other measure to deal with the issue, he added.

Mission Control has been discussing the problem with the astronauts on the station throughout the afternoon. Hadfield said he and his crewmates had noticed the rate of the leak varied depending on the orientation of the station with the sun, suggesting particular angles allowed the ammonia coolant to leak more quickly.

He asked Mission Control to send the crew a summary of what they know about the problem, and the possible courses to take to address it, before their bedtime.

"It would just be good for the six of us to know," Hadfield said.NASA and its Russian counterpart Roscosmos are discussing a possible emergency spacewalk that the US crewmembers may have to take to fix the leak.

“They [NASA] have a serious problem, really serious. In situations like these we must make concessions as a partner,” Russia's ISS mission chief Vladimir Solovyev explained.Read the full story here, more here.