Space, he said, "is a high-risk investment" and China "as a developing country is limited and constrained by its funding for more ambitious programs."

Luo said that China spent about 500 million dollars per year on its space program, a mere pittance compared to the 16.8 billion NASA has requested from the US Congress for fiscal 2007, beginning in October.

Luo also said China was planning several unmanned lunar missions, beginning with an orbital mission next year, a landing in 2012, and bringing samples of lunar material back to Earth by 2017.

With two manned missions orbiting Earth so far, China is third behind the United States and Russia in sending men into space.

Luo said China was planning to have a low-cost, non-polluting, 25-ton capacity launch vehicle ready by 2011.

The Chinese space agency was also planning to place seven observation satellites in orbit to monitor the environment, the first of which will study the Earth's magnetic field as an indicator of seismic activity.

Luo and his delegation have visited NASA's Goddard Space Flight Center, in a Maryland suburb outside Washington, and will take part in the Space Symposium in Colorado Springs later this week.

Their tour comes only two weeks ahead of Chinese President Hu Jintao's April 20 visit to Washington.