NASA had to end a spacewalk earlier than expected because of the astronaut's helmet was leaking water, Florida Today reported.
The excursion was supposed to take place outside the International Space Station (ISS) Tuesday, but was called off for safety precautions.
"The team down here in Mission Control is taking the cautious path and ending the spacewalk early," NASA mission commentator Dan Huot said.
About half a liter of water had leaked into European Space Agency astronaut Luca Parmitano just before he and Chris Cassidy started their second spacewalk in seven days.
Huot said neither was in any danger but that they would head back to the U.S. Quest airlock just to be safe. The cause of the leak has not yet been revealed, although the astronauts speculated it was water from Parmitano's drinking-water bag.
Parmitano, a former test pilot, became the first Italian spacewalker last week on the pair's July 9 mission. He and Cassidy, a former Navy SEAL and veteran spacewalker, ventured out to perform numerous maintenance repairs and to collect scientific data.
Among their tasks for the cancelled spacewalk were laying electrical and Ethernet cables between the U.S. and Russian sections of the station. The cabling is ultimately meant for the launch of a multipurpose module from Kazakhstan later this year. It will triple as an airlock, a laboratory and an docking department.
The rest of their objectives for the mission were installing jumper cables inside the station in the event of a power generator or cooling system failure, replacing a Japanese Kibo research facility camera and relocating wireless television camera equipment.
Cassidy and Parmitano did not perform the ISS' shortest spacewalk. That record belongs to Russian cosmonaut Gennady Padalka and U.S. astronaut Mike Fincke when they cut their venture to 14 minutes in 2004 after an issue with the pressure in Fincke's suit.
The ISS began construction in 1998 and the most recent spacewalk was the 171st in the station's history.
