(The Telegraph) The launch of the Dragon space capsule atop the Falcon 9 rocket, which took off at 3.44am (8.44am BST) from Cape Canaveral, Florida, on a mission to carry supplies to the orbiting research lab.
The test flight – which should include a fly-by and berthing with the station in the coming days – aims to show that private industry can restore US access to the ISS after NASA retired its space shuttle fleet last year.
No humans are travelling aboard the Dragon, but six astronauts are already at the $100-billion space lab to help the capsule latch on, to unload supplies and then restock the capsule with cargo to take back to Earth.
The Saturday launch attempt was scrubbed at the last second when computers detected high pressure in the central engine of the Falcon 9.
SpaceX engineers discovered the root cause was a faulty check valve.
California-based SpaceX is the first of several US competitors to try sending its own spacecraft to the ISS with the goal of restoring US access to space for human travellers by 2015.