Elon Musk is rebranding SpaceX's Mars-colonizing spaceflight system yet again.

The huge, reusable rocket-spaceship duo that SpaceX is building to ferry people to the Red Planet and other celestial destinations will no longer be called the BFR ("Big Falcon Rocket") and BFS ("Big Falcon Spaceship"), respectively.

"Renaming BFR to Starship," Musk announced via Twitter last night (Nov. 19). [The BFR in Images: SpaceX's Giant Spaceship for Mars & Beyond

"Technically, two parts: Starship is the spaceship/upper stage & Super Heavy is the rocket booster needed to escape Earth’s deep gravity well (not needed for other planets or moons)," the billionaire entrepreneur added in another tweet.

Musk has had a hard time settling on a name for his Mars spaceflight architecture. He called the initial concept the Mars Colonial Transporter, then changed the moniker to Interplanetary Transport System (ITS) in 2016. ITS became the BFR-BFS in September 2017, when Musk revealed an updated design for the combo.

If "Starship" strikes you as an ambitious moniker, you're not alone; one Twitter user noted that the vehicle will have to journey to another star system to truly earn the name. To which Musk responded: "Later versions will."

More than just the name of the Super Heavy-Starship system is in flux. In September of this year, Musk unveiled a significant new design for the architecture, which makes the spaceship look a lot like the vehicle used by the cartoon character Tintin. Then, just a few days ago, he announced that SpaceX is working on a new design iteration, which he described as a "radical change" and "delightfully counterintuitive," without providing details.

SpaceX's Mars rocket will be the most powerful launcher ever built, and the spaceship will be capable of carrying about 100 people per trip. Together, the vehicles will help get people to the moon, Mars, the Jupiter moon Europa, the Saturn satellite Enceladus and everywhere else they want to go in the solar system, according to Musk's plan.

If everything goes well, the first crewed Mars flight with the system could come in the mid-2020s, Musk has said.

SpaceX also plans to shift all of its business over to the Super Heavy-Starship system eventually. Together, the two vehicles can do everything the company will need to do for the foreseeable future, from launching satellites to cleaning up space junk to carrying passengers on superfast trips from city to city here on Earth.

Mike Wall's book about the search for alien life, "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate) is out now. Follow him on Twitter @michaeldwall. Follow us @Spacedotcom or Facebook. Originally published on Space.com