• The SpaceX flight represents the ninth crew rotation mission to the station under NASA's commercial crew program.
• Originally scheduled for an Aug. 18 launch, the Crew-9 mission was waylaid when NASA and Boeing encountered a slew of obstacles that delayed the return of the Starliner craft.
• Once aboard the space station, NASA astronaut Nick Hague and Roscosmos cosmonaut Aleksandr Gorbunov will become members of Expedition 72, as will the Starliner crew..

The SpaceX vehicle that next year will ferry the Starliner astronauts back to Earth is preparing to finally depart for the International Space Station as early as this weekend.

Aboard the company's Dragon capsule will be two Crew-9 astronauts embarking to the orbital outpost for a six-month rotation to perform a slew of research and experiments. Originally scheduled for an August launch, the mission had been delayed while NASA and Boeing officials worked to figure out what to do about the troubled Starliner spacecraft taking up the Dragon's docking port.

Now that the Boeing Starliner capsule has returned to Earth intact – albeit, without its crew – the Dragon has been cleared for takeoff in the days ahead as mission operators wait out Hurricane Helene brewing on the state's panhandle.

And when the Crew-9 astronauts return from their voyage on the Dragon in February, they won't be alone. Joining them will be Suni Williams and Butch Wilmore, the NASA astronauts who in June flew to the station aboard the Starliner for what was supposed to be a 10-day stay.

Here's everything to know about the Crew-9 mission, including the launch and the plans for a return to Earth:

When does the SpaceX Crew-9 mission launch?

In August, NASA had delayed the Crew-9 launch to no earlier than Tuesday amid the scramble to figure out what to do about the Starliner, which encountered multiple problems during its trip to orbit.

Now that the week of the scheduled launch has arrived, it still remains unclear just when the Dragon will be able to takeoff from Florida on top of a Falcon 9 rocket. NASA and SpaceX have postponed the launch three times so far in recent days as a storm with hurricane potential brews off the Florida Gulf Coast.

As of now, the earliest possible launch opportunity is 1:17 p.m. EDT Saturday, the U.S. space agency said in a Tuesday blog post. The rocket rolled out Tuesday to Space Launch Complex 40 the Space Force Station in Cape Canaveral after the crew arrived Saturday to quarantine.

After integrating the rocket and capsule for a launch rehearsal Tuesday night, the vehicle was to move back to the hangar ahead of any potential storm activity, NASA said.

What is Crew-9?

The SpaceX flight represents the ninth crew rotation mission to the station under NASA's commercial crew program as the agency shifts to paying private companies for missions it once would carry out itself.

The Crew-9 astronauts are to relieve Crew-8, whose team have been at the space station since March.

While aboard the orbital laboratory, the Crew-9 astronauts will spend six months conducting experiments, research demonstrations and spacewalks to perform maintenance on the space station. Much of it will be to prepare for human exploration deep into the cosmos.

Why was the Crew-9 mission delayed?

Originally scheduled for an Aug. 18 launch, the Crew-9 mission was waylaid when NASA and Boeing encountered a slew of obstacles that delayed the return of the Starliner craft.

Boeing had spent years developing and testing the vehicle ahead of the inaugural crewed test flight, which managed to launch June 5 after a few delays of its own. Hopes were high that the demonstration would pave the way for Starliner to compete with SpaceX carrying cargo and crews to the space station for NASA.

But when Williams and Wilmore arrived on June 6 at the space station, engineers discovered that the Starliner craft had experienced multiple helium leaks and had issues with its propulsion system. The troubles were concerning enough for NASA to first delay Starliner's return flight, and then the SpaceX Crew-9 launch as officials figured out a plan for how the rest of the mission would unfold.

That decision was made official in late August when NASA Administrator Bill Nelson announced that the agency had determined that the vehicle wasn't up to the task of reliably transporting Wilmore and Williams home. Instead, the Starliner capsule undocked Sept. 6 from the space station to make its journey back to the ground without its crew.

Now, Wilmore and Williams are scheduled to remain at the space station for another five months and return in February, hitching a ride on the Dragon when the Crew-9 astronauts complete their six-month shift.

Meet the astronauts of Crew-9

Before the Starliner woes, the Crew-9 mission was slated to include a full contingent of four astronauts.

But now that the Starliner astronauts are in need of a ride home, just two Crew-9 astronauts will head to the space station aboard the Dragon to leave room for Wilmore and Williams, NASA said.

The two astronauts of Crew-9 are:

◾ NASA astronaut Nick Hague, of  Belleville, Kansas, will serve as crew commander, making this his third launch and second mission to the space station. Selected as a NASA astronaut in 2013, Hague, also an active-duty colonel in the U.S. Space Force, has spent 203 days in space and conducted three spacewalks.

◾ Roscosmos cosmonaut Aleksandr Gorbunov will embark on his first trip to the space station as a mission specialist. The Russian studied engineering at the Moscow Aviation Institute, graduating with a specialty in operating and repairing aircraft before his selection as a cosmonaut in 2018.

NASA astronauts Zena Cardman and Stephanie Wilson, previously announced as crewmates for the mission, are eligible for reassignment on a future mission, NASA said.

Crew-9, Starliner astronauts to be part of Expedition 72

Once aboard the space station, Hague and Gorbunov will become members of Expedition 72, as will the Starliner crew.

NASA officials have insisted that Wilmore and Williams, both veteran astronauts, who have each been to space twice, were trained and prepared for the possibility of an extended mission. Until they return next year with Crew-9, the astronauts will continue to help with scientific research and routine maintenance.

"We always miss our families. I miss my two dogs. I miss my friends," Williams said recently in a media briefing from the space station. "There's so many people on Earth that are sending us messages, and it makes you feel just right at home ... everybody understands, and everybody's cheering for us to get back with Crew-9."

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [email protected]