LEAGUE CITY, TX - China's space program is about three decades from landing astronauts on the Moon, but will make significant strides during that time, according to one expert following the nation's human spaceflight efforts.

"They're probably as close to the Moon as we are to Mars," space policy expert James Lewis said of China Wednesday during the annual meeting here of the American Astronautical Society (AAS). "They say that their goal is a lunar base...[but] it's not a near-term possibility."

Lewis, a senior fellow and director of technology policy at the Center for Strategic and International Studies, said China's lack of a sufficient heavy-lift launch vehicle will require the nation to wait until the development of its Long March 6 rocket - which will follow the yet-to-be completed Long March 5 booster - before a manned lunar flight can take place.

At least three more missions are expected to follow China's successful Shenzhou 6 spaceflight - the country's second flight to carry astronauts and its first to launch a two-person crew - which flew in October. Shenzhou 7 is slated to launch three astronauts in 2007, with two more to flights expected before the country's Shenzhou 10 mission delivers astronauts to a pair of linked orbital modules from Shenzhou 8 and 9 by 2012, Lewis said.

"These capsules, if they do link up, will form a space lab," Lewis said. "[China's] goal is to build a permanent space station."

China's Shenzhou spacecraft are based on the Russian Soyuz vehicle and consist of a propulsion module, a crew compartment and an orbital module. But the Shenzhou version is larger and can leave its orbital module - which carries its own solar arrays and maneuvering jets - in space for extended periods.

The fact that China selected a Soyuz model - which Russia routinely uses to ferry new crews to the International Space Station (ISS) -for its Shenzhou spacecraft could indicate some foresight of future international cooperation, though near-term partnerships with the U.S. would be difficult due to current political climate, Lewis said.

"China is interested in its independent program and not in being a junior partner," Lewis said, adding that there are also security concerns due to the military component of China's space program.

Shenzhou spacecraft launch atop a Long March 2F rocket, though China space officials have said that future Long March 5 boosters could launch up to 28 tons into orbit with a lifting power comparable to Europe's Ariane 5 vehicle, he added.

But China's manned expeditions are only part of its spaceflight ambitions to win national prestige and demonstrate technological prowess.

The China National Space Administration plans to launch its first Moon probe - dubbed Chang'e 1 - in 2006, with landers and sample return spacecraft to follow by 2020. The initial Chang'e lunar orbiter will fly on a modified version of a Chinese commercial communications satellite, indicating a smooth flow of technology between commercial and research space industry, Lewis added.

While Chinese space officials have said the Shenzhou 6 mission cost about $110 million - relatively cheap when compared to other national space programs - Lewis said it's possible the flight cost up to three times that based on past understatements of the nation's spaceflight costs.

However, China does spend about one-half of 1 percent of its gross domestic product (GDP) on its space program, and since the nation's GDP has risen 30 percent since 2002 due to a booming economy, more funding is expected

"They will have a lot more money and are willing to spend it," Lewis said. "It's going to be a well-funded program."