WASHINGTON - SpaceX CEO Elon Musk said that the private space company’s next-generation heavy-lift rocket Starship is expected to be launched into orbit in six months.

Musk spoke in front of a 50-meter, 200-ton Starship prototype at the SpaceX launch facility in Texas Saturday night, revealing more details about the spacecraft designed for full “rapid reusability,” according to the SpaceX website.

SpaceX has already completed two, low-altitude “hop” flights with the Starhopper, a stub-top, prototype cylinder with one of the Raptor engines to be used in Starship. In the coming one or two months, Starship Mk1 will have its first test flight to a sub-orbital altitude of about 65,000 feet (19,812 meters), and then Starship Mk2 will have a similar test, according to Musk.

Starship Mk3 or Mk5, covered with full sheets of stainless steel and welded with a single weld, might be an orbital launch with the full Super Heavy booster in the coming six months, according to Musk.

Musk also said he was optimistic that SpaceX could be flying people on test flights of Starship as early as next year.

The 118-meter-tall, completely reusable Starship will provide affordable delivery of significant quantities of cargo and people, essential for building moon bases and Mars cities. It will ultimately carry as many as 100 people on long-duration, interplanetary flights, according to SpaceX.

As Elon Musk, the founder and chief executive of SpaceX, had repeatedly said that he created a rocket company because he wanted to colonize Mars. His fervent argument is that humanity must spread to a second planet as insurance for long-term survival.

“Which future do you want?” he asked near the start of a presentation on Saturday night at a launch site near the southern tip of Texas, during which he said the options were being “confined to Earth” or become a spacefaring species.

Mr. Musk said, “I hope the audience agreed that humans should prepare for life elsewhere in the solar system.” 

Standing before the prototype and an older rocket built early in the company’s history, he pledged that Starship would first take off to an altitude of 65,000 feet and then land, “in about one to two months.”

“This is going to sound totally nuts,” he said later, “but I think we want to try to reach orbit in less than 6 months,” adding that this timeline relied on continued improvements in manufacturing the rockets.

Starship is the latest name for the upper stage of what Mr. Musk had been calling B.F.R. The “B” stood for Big, the “R” stood for Rocket, and Mr. Musk never publicly stated the meaning of “F.”