BROWNSVILLE, Texas — SpaceX Chief Executive Elon Musk said the company would start test flights of its next-generation Starship vehicle in as soon as one to two months and reach orbit in as little as six months, even as some complain the company is devoting too many resources to this project.

Musk provided an update on SpaceX’s work on the Starship vehicle in a Sept. 28 presentation at the company’s South Texas site, where the first Starship prototype, called Mark 1, is being assembled. The Mark 1 vehicle, 50 meters tall, served as the backdrop for Musk’s talk to media, employees and other guests at the site east of Brownsville.

That vehicle, he said, would make a high-altitude suborbital flight in the near future from the Texas site, known as Boca Chica. “This thing is going to take off, fly to 65,000 feet, about 20 kilometers, and come back and land, in about one or two months,” he said.

The overall test program, he said in a later question-and-answer session with media, would move “very fast.” After the 20-kilometer test flight, he said the company might move ahead directly to an orbital flight using a Starship prototype and a Super Heavy booster. That orbital flight, he said, would be done with a new Mark 3 prototype, construction of which he said would start in about a month at Boca Chica.

“We are going to be building ships and boosters at Boca and the Cape as fast as we can,” Musk said. “We’re improving both the design and the manufacturing method exponentially.”

The company is also building a Starship prototype, known as Mark 2, in Cocoa, Florida, near Cape Canaveral. That Mark 2 vehicle, he said, should be done within a couple months, with the Mark 3 vehicle in “maybe three months.”

While Musk said in a response he described as “stream of consciousness” that the orbital flight would be done with the Mark 3 prototype, he said a few minutes later that first orbital flight would be done with a Mark 4 or Mark 5 prototype, construction of which would closely follow Mark 3. “This is going to sound totally nuts, but I think we want to try to reach orbit in less than six months,” he said, a schedule he estimates to be “accurate to within a few months.”

Those initial test flights will all be uncrewed. However, he said the first flights with people on board could take place as soon as next year, a schedule that is remarkably fast given that SpaceX has yet to fly people on its Crew Dragon spacecraft it has been developing for many years for NASA.

Beyond the schedule for test flights, Musk made few major announcements at the event. His talk was largely a technical discussion of the Starship architecture, including an explanation for why the company switched less than a year ago to using a version of stainless steel called type 301 for the structure of the vehicle. That steel, he said, is a better choice than lightweight carbon composites since it handles high temperatures better, limiting the need for thermal protection systems to lightweight ceramic tiles on the “windward” side of the vehicle that faces the atmosphere during reentry.

“A 301 stainless steel rocket is actually the lightest possible reusable architecture,” he said. He added that steel cost only about two percent that of carbon composite materials. “It’s a good thing we changed from carbon fiber to steel, by far.”

The ambitious test schedule that Musk proposed at the event, though, faces challenges that go beyond the building of Starship prototypes. SpaceX spent much of the summer working with the Federal Aviation Administration, which licenses commercial launches, to amend an experimental permit to ultimately allow a single test flight to 150 meters of the smaller Starhopper vehicle, which took place successfully at Boca Chica Aug. 27. That delay was caused by work on a hazard analysis for the vehicle.

The company does not yet have a new experimental permit or launch license for Starship, a much larger vehicle that will fly much higher. Musk praised the head of the FAA’s Office of Commercial Space Transportation, Wayne Monteith, as “very forward leaning” in the licensing process.

“The FAA asks good questions and wants to make sure things are safe, as do we,” he said. “I feel pretty optimistic about things. I don’t see any fundamental obstacles.” He didn’t specify, though, how far along the company is in the process to get a permit or license for Starship.

Increased launch activity at the Texas site will pose challenges for the residents of Boca Chica Village, a small subdivision of a few dozen homes a couple kilometers from the launch pad. During the Starhopper test in August, residents were advised by local law enforcement to stand outside in the event an explosion broke windows in the houses.

Musk acknowledged that SpaceX had offered to buy the homes of residents in the subdivision recently, as first reported Sept. 18 by Business Insider. “Over time, it’s going to be quite disruptive to living in Boca Chica Village, because it’ll end up needing to get cleared for safety a lot of times,” he said. “Probably over time it would be better to buy out the villagers, and we’ve made an offer to that effect.”

SpaceX also faces criticism from some that the company appears to be focusing more attention on Starship than on projects like Crew Dragon, the NASA-funded project to restore American orbital human spaceflight that is well behind schedule.

Those critics include NASA Administrator Jim Bridenstine, who issued a brief statement Sept. 27. “I am looking forward to the SpaceX announcement tomorrow,” he said. “In the meantime, Commercial Crew is years behind schedule. NASA expects to see the same level of enthusiasm focused on the investments of the American taxpayer. It’s time to deliver.”

Asked about Bridenstine’s comment, Musk said that SpaceX is spending only a small fraction of its overall resources on Starship. “Our resources are overwhelmingly on Falcon and Dragon,” he said, with less than five percent of the company working on Starship. He didn’t state if moving those resources onto Crew Dragon would speed up its development.

Musk also used his speech to reiterate his long-term vision of sending humans to the moon and Mars to make humanity “multiplanetary,” but didn’t give firm timetables for such flights in his talk.

“I think we should really do our very best to become a multiplanet species and to extend consciousness beyond Earth,” he said at the conclusion of his 40-minute talk, “and we should do it now.”