US astronauts Barry Wilmore and Terry Virts have made speedy work of their third spacewalk in eight days to ready the International Space Station for the arrival of more commercial spacecraft, despite a small malfunction.

Flight engineer Mr Virts found a small amount of water building up in his helmet after he re-entered the space station.

A similar problem occurred after Wednesday’s spacewalk, when about three inches of water collected in Mr Virts’ headpiece, but NASA said the problem did not put the astronauts in danger.

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The duo completed their tasks in five hours and 38 minutes, about an hour earlier than planned.

Flight engineer Terry Virts honours the deceased Mr Spock actor Leonard Nimoy. Photo: Twitter

“You guys have done an outstanding job, even for two shuttle pilots,” said Suni Williams, herself a veteran shuttle astronaut and spacewalker who, working from mission control in Houston, led the men through their tasks in orbit.

The astronauts each installed a boom with two antennas for a communications system so that future crews launching from Florida on US commercial spacecraft will be able to park at the space station, NASA said.

Then they routed 122 metres of cable, securing it with copper wire ties as they manoeuvred across handrails on the space station.
Sunday’s spacewalk was one of many planned for the coming year to prepare the space station for a new era in human spaceflight, when more commercial vehicles will be arriving at the research outpost carrying astronauts.

Mr Virts honoured his childhood hero, Star Trek actor Leonard Nimoy, on Twitter last week, throwing the ‘Live long and prosper’ hand gesture made popular by the Mr Spock character.

– with AAP.