A new flaw has emerged with a US-made spacesuit, forcing NASA to delay until Christmas Eve the next outing to repair the International Space Station.

The problem came up in a system that handles water condensation in veteran astronaut Rick Mastracchio’s spacesuit after he re-entered the space station airlock following a spacewalk that lasted more than five hours, NASA said.

It was not believed to be the same type of issue that caused a dangerous water leak in the helmet of Italian astronaut Luca Parmitano in July.

An investigation into that situation is ongoing.

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Faced with unexpected repairs due to an equipment cooling breakdown at the orbiting lab on December 11, NASA arranged makeshift snorkels inside the 35-year-old spacesuits and absorbent pads in the helmets for these spacewalks in case such a leak happened again.

“During repressuristion of the station’s airlock following the spacewalk, a spacesuit configuration issue put the suit Mastracchio was wearing in question for the next excursion – specifically whether water entered into the suit’s sublimator inside the airlock,” the space agency said in a statement.

“This issue is not related to the spacesuit water leak that was seen during a July spacewalk.”

Now, astronauts are resizing a spare spacesuit aboard the ISS for Mastracchio, 53, to wear on the next spacewalk to complete the pump replacement.

The outing was planned for Monday, but will now take place on Tuesday, beginning at 7:10am (2310 AEDT).

NASA released the news late on Saturday, after the spacewalk by the two American astronauts ended with the successful disconnection and removal of the old pump.

NASA mission control in Houston checked in with them frequently to see if they were experiencing any wetness in their helmets, and each time the spacewalkers reported no problems.

Space agency officials told reporters this week that Hopkins, 44, would be wearing the suit Parmitano had worn when he experienced the leak that nearly drowned him, noting its water pump system had been replaced.

The spacewalks were called for after a faulty valve forced a partial shutdown in the system that regulates equipment temperature at the space station.