The US space shuttle Endeavour launched from its base in Florida last night.
It is due to deliver and install an outdoor platform for science experiments on the International Space Station.
Endeavour blasted off from the Kennedy Space Center at 6:03pm (11.03pm Irish time), carrying a crew of seven astronauts on a 16-day mission to the $100bn orbiting research outpost.
The six US citizens and one Canadian on board are scheduled to reach the ISS tomorrow.
They will install a platform for astronauts to conduct experiments 350km above the Earth's surface.
Eight minutes after launch the shuttle entered orbit 225km above Earth, and a few moments later the shuttle could be seen successfully separating from the external fuel tank.
A US space agency official played down the potential damage caused by debris that peeled off from Endeavour's external fuel tank during liftoff and could be seen hitting the shuttle about two minutes into the flight in images broadcast on NASA TV.
The debris could be ice or foam that broke off from the external fuel tank, said Bill Gerstenmaier, NASA associate administrator for space operations.
NASA has been cautious about conditions for the space shuttle's exit and return since the shuttle Columbia blew apart some 20,000m above the Earth in 2003 as it was returning from a 16-day space mission to land in Florida.
Endeavour's launch had been scrubbed three times since Saturday due to inclement weather.
Two earlier attempts in June were aborted after potentially hazardous leaks to the shuttle's external fuel tank were discovered.
The aborted attempts left the US space agency footing $4.5m in extra costs.
Coincidentally, today marks the 40th anniversary of NASA's first Moon landing mission, Apollo 11.
Read more about the 1969 Apollo 11 mission
