NASA astronaut Terry Virts Flight Engineer of Expedition 42 is seen working to complete a cable routing task while the sun begins to peak over the Earth's horizon on the International Space Station, in this handout photo taken February 21, 2015, provided by NASA.[Photo/Agencies]

WASHINGTON - A pair of US astronauts ventured outside the International Space Station on Wednesday for the second of three spacewalks to prepare the orbiting lab for future American crew spacecraft.

The nearly seven-hour spacewalk by astronauts Barry Wilmore and Terry Virts went smoothly with all the scheduled tasks completed, but back inside the station's airlock, Virts reported a small amount of water floating free in his helmet.

There was no report of water during the spacewalk itself and the crew was never in any danger, NASA said in a statement.

During their first spacewalk on Saturday, the two astronauts spent six hours and 41 minutes outside deploying eight bundles of cables. Wednesday's spacewalk featured more cable work.

Wilmore and Virts "completed rigging a series of power cables on Pressurized Mating Adapter-2, lubricated the Latching End Effecter of the space station's Canadarm2 robotic arm, and prepared the Tranquility module for the station's upcoming reconfiguration in preparation for the arrival of commercial crew vehicles later this decade," the US space agency said.

"They also were able to complete get-ahead work for the installation during Sunday's spacewalk of the Common Communications for Visiting Vehicles system by pre-staging wire- ties that will be used to secure some 400 feet (122 meters) of cable," it added.