Miami: Two US astronauts on Sunday made speedy work of their third spacewalk to get the International Space Station ready for the arrival of more commercial spacecraft in the coming years.

Tethered to the outside of the orbiting outpost, space station commander Barry Wilmore and flight engineer Terry Virts reported no problems with their spacesuits during the outing, but Mr Virts discovered 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.

Still, the US space agency has expressed concern about repeated technical failures in the American spacesuits, all linked to the same cooling system and a 2013 emergency water leak that nearly drowned Italian spacewalker, Luca Parmitano.