Buzz Aldrin, the American astronaut who was the second man to walk on the Moon, said Wednesday that the United States must lead the way toward building a permanent settlement on Mars.

Speaking at a conference of space experts in the US capital, the 83-year-old said the United States should apply what it learned decades ago by reaching the moon toward building a new colony on the Red Planet.

"The US needs to begin homesteading and settlement of Mars," Aldrin said at the Humans to Mars conference at George Washington University. "It is within reach."

His call for US leadership in the space race to Mars largely lines up with plans set forth by NASA and President Barack Obama's administration to send the first people to Mars in the 2030s.

But unlike NASA Administrator Charles Bolden, who acknowledged at the start of the three-day conference on Monday that significant technological gaps remain, Aldrin said the bulk of the research has already been done.

"There is really very little new research that is required," Aldrin said, calling for cash investment and political will to sustain the vision of a permanent dual-planetary society.

"The US needs to continue to be the human space transportation leader and I think we can capitalize on the dynamism of the commercial market to develop a landing system that can truly become the basis for a US highway to space."

Aldrin, who has authored a new book titled "Mission to Mars: My Vision for Space Exploration," said the title should have been "Missions to Mars" since the trips will be many and the human presence should be continuous.

"We are talking about multiple missions to eventually settle and colonize Mars," said Aldrin, who also plugged his plan to send spacecraft on cycling orbits that would engage in perpetual trajectories between Earth and Mars.

"We should focus our attention on establishing a permanent human presence on Mars by the 2030-2040 decade.

"The United States will be a beacon for the development of humanity."

Aldrin described how there could be different modular habitats on Mars, perhaps built by the world's various space agencies from China, Europe, India, Japan and Russia, with the United States in the leadership role.

He said a first step would be to send three people to the Martian moon Phobos "and use that year and a half to oversee the robotic deployment of the international Mars base."

He derided those who have suggested that people who make the trip to Mars may be able to come back to Earth afterward.

"There is no other choice than to commit to permanence on Mars," Aldrin said. "I just don't think you can have one-shot forays to the surface of Mars."

Aldrin appeared to support the Inspiration Mars idea, put forth by astronaut Dennis Tito, to send two humans on a flyby of Mars beginning in 2018, saying that "could make it very clear that our mid-century goal is permanence on Mars."

As to Mars One, the Dutch company that recently announced it was recruiting volunteers for a one-way trip to the Red Planet in 2023, Aldrin said the plan appeared to have good fundraising and public relations appeal but "not much technical basis behind it."

Aldrin was the lunar module pilot on Apollo 11. On July 20, 1969, he and Neil Armstrong became the first humans to set foot on the moon.