The US space shuttle Endeavour has soared into orbit carrying an observation deck for the International Space Station, a seven-windowed dome offering breathtaking views.
The picture-perfect launch lit up the night sky at 4.14am on Monday (2014 AEDT), after a first attempt was scrubbed on Sunday due to heavy clouds over the launchpad in Cape Canaveral, Florida.
The spacecraft and its crew of six astronauts reached orbit about eight-and-a-half minutes later.
It was likely the last night time launch as the shuttle program nears retirement, with just four scheduled flights left.
"We wish you good luck and Godspeed, and see you in about two weeks," launch director Mike Leinbach told the crew shortly before lift-off.
The Endeavour mission's main goal is to deliver the massive Tranquility module, also known as Node 3, which comes with a multi-window cupola attached.
Built for NASA by the European group Thales Alenia Space in their Turin factory, the cupola will provide unparalleled panoramic views of earth and space.
Six windows arrayed along its sides and another on top - all protected against the impact of tiny meteorites - will provide an unprecedented, wide-ranging view for those onboard and help crew members monitor spacewalks and docking operations.
The cupola can accommodate two crew members at a time, and is equipped with portable workstations that can control station and robotic activities.
Installing the Tranquility module amounts to a major construction job, requiring a team of two astronauts to undertake three spacewalks lasting six-and-a-half hours each, the National Aeronautics and Space Administration (NASA) said.
Once the room is in place, the space station will be 90 per cent complete.
The module, named after the lunar sea where Apollo 11 landed, has the most sophisticated life support system ever flown into space - air revitalisation, oxygen generation and water recycling systems, as well as a waste and hygiene compartment for the crew.
The blast-off was "an important event", said Jean-Jacques Dordain, European Space Agency director-general.
"Even more important for us because the shuttle was full of European hardware," he said.
The mission, one of five scheduled for NASA's three shuttles before the program 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 its plan to send astronauts back to the moon by 2020.
The Constellation program was intended to develop a successor spacecraft to the shuttle, which could carry astronauts to the moon. They could then use a lunar base to launch manned missions to Mars.
Constrained by soaring deficits, 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 program ends.
Tranquility is seven metres long and has a pressurised cylindrical hull 4.5 metres in diameter, with a shallow conical section enclosing each end. Together with the cupola, it weighed more than 15 tonnes at launch.
The ISS, a joint project involving 16 countries, has cost around $US100 billion ($A114.9 billion), mostly funded by the United States.
Under Obama's new budget, the floating research station could see its life extended by five years until 2020.