NEW YORK — NASA aborted a planned six-hour spacewalk by two astronauts outside the International Space Station today when a one of the spacewalkers reported “a lot of water” inside his spacesuit helmet, a potentially scary situation.

European Space Agency astronaut Luca Parmitano reported that helmet started filling with water, making it difficult for him to continue the spacewalk outside of the international space station. The spacewalk ended after one hour and 32 minutes. It was supposed to last six hours and 15 minutes.

“There is some in my eyes, and some in my nose,” Parmitano said. “It’s a lot of water.”

Parmitano reported the water in his spacesuit about one hour and nine minutes into the spacewalk. The cause of the water leak is not yet known, but the tasks scheduled for the spacewalk can be deferred until a later excursion, NASA officials said. 

Cassidy and Parmitano began today’s spacewalk at 7:57 a.m. EDT. They wore NASA-issue spacesuits called Extravehicular Mobility Units, or EMUs. It ended at 9:29 a.m. EDT.

“[Mission Controllers on the ground] are taking the cautious path and ending the EVA early,” a NASA spokesman said during a broadcast on NASA TV. 

Parmitano headed straight back to the U.S. Quest airlock on the international space station while Cassidy followed. Cassidy assured Parmitano repeatedly that he was close behind.

Once inside the airlock, the astronauts began repressurizing the chamber in order to return inside the station. At one point, Cassidy said it looked as if Parmitano could not hear any calls over his spacesuit radio.

“He looks fine,” Cassidy said. “He looks miserable, but okay.”

Today’s spacewalk was the second in eight days for Parmitano and Cassidy. The two astronauts planned to continue work that will prepare the station for the arrival of a new Russian multipurpose laboratory module slated to arrive later this year, and perform other maintenance tasks.