SpaceX has launched a load of supplies to the International Space Station following a pair of unusual power delays.

A Falcon rocket raced into the pre-dawn darkness today, carrying a Dragon capsule with about 2,500 kilograms of goods. This recycled Dragon -- which is making its second space voyage -- is due to arrive at the orbiting lab early Monday.

That's when Canadian astronaut David Saint-Jacques will be pressed into duty, manning the Canadarm 2 to perform his first-ever "cosmic catch" manoeuvre, backed up by NASA astronaut Nick Hague.

Part of the cargo aboard the Dragon vehicle is 1.2 million tomato seeds heading to space as part of the Tomatosphere educational project.

The Canadian Space Agency says in a release the seeds will return to Earth a month later, along with blood and breath samples for a Canadian health probe into the impact of living in space on astronauts' bone marrow.@

The delivery is a few days late because of electrical power shortages that cropped up first at the space station, then at SpaceX's rocket-landing platform in the Atlantic. Both problems were quickly resolved with equipment replacements: a power-switching unit in orbit and a generator at sea.