Nasa has launched the US shuttle Discovery for a mission to the International Space Station (ISS), with seven astronauts on board.
It lifted off from the Kennedy Space Center in Florida at 2359 EDT Friday (0359 GMT Saturday).
Two previous attempts to launch the orbiter had been postponed by a mix of bad weather and a technical glitch affecting its main propulsion system.
Discovery's mission will be the 30th flight dedicated to ISS maintenance.
Science equipment and a freezer to store research samples are among the items on board.
It also carries a new sleeping compartment, an air purification system and a treadmill to help maintain astronauts' health.
The shuttle entered orbit eight-and-a-half minutes after launch, and is due to arrive at the ISS on Sunday night.
Nasa plans an additional six sorties to the orbiting platform before retiring its re-useable spaceship fleet at the end of next year or early in 2011.
Managers had been discussing an early Friday flight but decided to give their engineers an extra 23 hours to study the hydrogen stop-drain fuel-valve problem that thwarted the second launch effort on Wednesday.
Engineers now believe the unexpected signals they were getting from the propulsion system while filling the orbiter's giant external tank on Tuesday were related to a errant sensor.
Engineers needed more time to tackle a technical glitch
Heavy rain and lightning had intervened at the first launch attempt on Tuesday morning.
Discovery's 13-day mission is scheduled to include three spacewalks to replace exterior science experiments, prepare the platform for the arrival of a new module next year, and to install a new ammonia storage tank and return the used one.
Ammonia is used to move excess heat from inside the station to the radiators outside.
Discovery will also drop off US astronaut Nicole Stott for a three-month stay on the ISS, and pick up colleague Tim Kopra for the ride home. Kopra has been living on the platform for the past six weeks.
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