Humans could stay on the Moon for lengthy periods during this decade, a Nasa official has told the BBC.
Howard Hu, who leads the Orion lunar spacecraft programme for the agency, said habitats would be needed to support scientific missions.
He told Sunday with Laura Kuenssberg that Wednesday's launch of the Artemis rocket, which carries Orion, was a "historic day for human space flight".
Orion is currently about 134,000km (83,300 miles) from the Moon.
The 100m-tall Artemis rocket blasted off from the Kennedy Space Center as part of Nasa's mission to take astronauts back to Earth's satellite.
Sitting atop the rocket is the Orion spacecraft which, for this first mission, is uncrewed but is equipped with a 'manikin' which will register the impacts of the flight on the human body.
Wednesday's flight followed two previous launch attempts in August and September that were aborted during the countdown because of technical woes.
Mr Hu told Laura Kuenssberg that watching Artemis lift off was "an unbelievable feeling" and "a dream".
"It's the first step we're taking to long-term deep space exploration, for not just the United States but for the world," he said.
"And I think this is an historic day for Nasa, but it's also an historic day for all the people who love human space flight and deep space exploration.
"I mean, we are going back to the Moon, we're working towards a sustainable programme and this is the vehicle that will carry the people that will land us back on the Moon again."
Mr Hu explained that if the current Artemis flight was successful then the next would be with a crew, followed by a third where astronauts would land on the Moon again for the first time since Apollo 17 50 years ago in December 1972.
The current mission was proceeding well, he told the BBC, with all systems working and the mission team preparing for the next firing of Orion's engines (what is known as a burn) at lunchtime on Monday to put the spacecraft into a distant orbit of the Moon.
Mr Hu admitted that watching the mission from Earth was not unlike being an anxious parent, but he said seeing the images and the videos coming back from Orion "really gives that excitement and feeling of, 'wow, we are headed back to the Moon'".
One of the most critical phases of the Artemis I mission is getting the Orion module safely back to Earth. It will re-enter the planet's atmosphere at 38,000km/h (24,000mph), or 32 times the speed of sound and the shield on its underside will be subjected to temperatures approaching 3,000C.
Once the safety of Artemis's components and systems has been tested and proven, Mr Hu said the plan was to have humans living on the Moon "in this decade".
A large part of the reason for going back to the Moon is to discover whether there is water at the satellite's south pole, he added, because that could be converted to provide a fuel for craft going deeper into space - to Mars, for example.
"We're going to be sending people down to the surface and they're going to be living on that surface and doing science," Mr Hu said.
"It's really going to be very important for us to learn a little bit beyond our Earth's orbit and then do a big step when we go to Mars.
"And the Artemis missions enable us to have a sustainable platform and transportation system that allows us to learn how to operate in that deep space environment."
The Orion capsule is due back on Earth on 11 December.