It was the first of two supply runs to the lab complex in just 31 hours, with SpaceX gearing up for a Florida launching overnight Sunday.

In pre-dawn darkness, a workhorse Soyuz U booster carrying the Progress MS-03/64P cargo ship roared to life and climbed away from the Baikonur Cosmodrome in Kazakhstan at 5:41 p.m. EDT (3:41 a.m. Sunday local time). A little less than nine minutes later, the Progress was released to fly on its own, kicking off a 34-orbit rendezvous.

At the moment of launch, the space station was flying 252 miles above Chad in western Africa and if all goes well, the upgraded MS-series cargo ship, featuring improved avionics and navigation systems, will reach the station around 8:22 p.m. Monday, docking at the Earth-facing Pirs module.

On board the supply ship: 1,940 pounds of propellant, 110 pounds of oxygen, 926 pounds of water and 2,833 pounds of equipment, crew supplies and spare parts.

Several hours before the Progress took off, at 8:30 a.m. Saturday, SpaceX engineers at the Cape Canaveral Air Force Station in Florida test fired the nine Merlin 1D first-stage engines in a Falcon 9 rocket, a short "burn" to verify engine operation before committing the rocket to flight.