Endeavour shuttle astronauts wrapped-up a near six-hour spacewalk early yesterday, installing fluid tubes to the landmark observation deck on the International Space Station.
US astronaut Bob Behnken and British-born Nicholas Patrick used their second spacewalk of the mission - which Nasa said had been extended by a day - to connect two ammonia loops to the new Tranquility node, hooking it to the International Space Station's cooling system.
Mr Behnken, Mr Patrick and others aboard the ISS have so far been denied the out-of-this-world view that the observation cupola attached to Tranquility promises to deliver, however.
Nasa said shutters on the cupola's seven windows would be opened tomorrow, finally providing a panoramic view of space, Earth and visiting spacecraft, but also vital access for monitoring space walks and docking operations.
The spacewalkers also installed thermal covers on Tranquility to prevent condensation inside the module, outfitted a docking port and installed handrails.
Meanwhile, ISS Commander Jeff Williams and other crew members continued to outfit Tranquility's interior, including setting up the ventilation system.
The National Aeronautics and Space Administration also said mission managers had approved the addition of an extra day to the Endeavour's flight.
"That day, which will be a new Flight Day 11 beginning Wednesday afternoon, will be used to relocate two Water Recovery System racks, the Waste Hygiene Compartment and the Oxygen Generation System into Tranquility," the space agency said on its website.
"Those relocations were on hold pending the repairs conducted earlier in the flight, and enough run time on the system to generate needed samples for return to Earth for analysis."
The addition brings the length of the mission to 14 days, and moves the shuttle's expected landing date to February 21.
The cupola can accommodate two crew members at a time and is equipped with portable workstations that can control station and robotic activities.
Six windows are arrayed along its sides and another on top, all protected against the impact of tiny meteorites.
Once the installation of the new node is finished, the space station will be 90 per cent complete.
The Endeavour mission, one of five scheduled for Nasa's three shuttles before the programme ends later this year after a 29-year run, comes as the US space agency re-evaluates its future, after President Barack Obama effectively abandoned a US plan to send astronauts back to the moon by 2020.
Constrained by soaring deficits, Mr Obama submitted a budget to Congress that encourages Nasa to focus instead on developing commercial transport alternatives to ferry astronauts to the ISS after the shuttle programme ends.