Nine months after a SpaceX rocket exploded on the way to the International Space Station, the California-based company is counting down to the launch Friday of another flight to resupply astronauts in orbit.

The unmanned Dragon capsule is poised to blast off from Cape Canaveral, Florida at 4:43 pm (2043 GMT) atop a Falcon 9 rocket.

The spaceship will carry some 7,000 pounds (3,100 kilograms) of gear for the six astronauts living at the research outpost, including an inflatable space room astronauts will test in microgravity.

Known as the Bigelow Expandable Activity Module, the inflatable chamber will be temporarily attached to the space station.

Although SpaceX has successfully flown its newly upgraded Falcon 9 rocket twice since last year's accident, Friday will mark the first return flight to the ISS, the eighth in a series of resupply trips NASA has commissioned from SpaceX.

The company blamed the blast in June 2015 on a faulty strut in the Falcon 9's upper booster, which allowed a helium bottle to snap loose, causing the explosion of the rocket, cargo ship and all its contents just over two minutes into the flight.

After Friday's launch, SpaceX will make another attempt at landing Falcon 9's first stage on a floating platform in the Atlantic Ocean.

Although the company has managed to land stages upright on solid ground, multiple attempts at a water touchdown have failed.

"We certainly hope we are going to nail the landing this time," SpaceX Vice President Hans Koenigsmann said.

The effort is part of CEO Elon Musk's ongoing bid to lower the cost of launching to space by making rocket components reusable.

Expensive rocket parts are currently jettisoned into the ocean after launch.

- Crowded space station -

If all goes well, the Dragon will become the fourth vehicle to visit the ISS in four weeks.

Set to dock at the space station on Sunday, the capsule would join its competitor, Orbital ATK's Cygnus cargo craft, which launched to the station last month and remains attached to the orbiting space laboratory.

Dragon's arrival will mark the "first time that the two vehicles, contracted by NASA and developed by private industry to resupply the station, are connected to the space station at the same time," the US space agency said.

In addition to the Cygnus, four Russian spacecraft -- two Soyuz crew capsules and two Progress cargo vehicles -- are docked at the ISS.

Six capsules parked at the station would tie a record for most vehicles there at once. That last happened in 2011.

The weather forecast was 90 percent favorable for liftoff, with clear skies and light winds expected on Friday.

"It will be a great day to launch a rocket," NASA weather officer Kathy Winters said.

The agency plans to broadcast the Dragon's arrival at the ISS early Sunday, beginning at 5:30 am (0930 GMT).