HOUSTON - The United States welcomes other nations that wish to join the endeavor of the peaceful exploration of space, a NASA spokesperson said Friday while commenting on China's imminent launch of its Shenzhou IX?manned spacecraft.

"The United States has been engaged in the peaceful exploration of space for more than 50 years, and we welcome those other nations that wish to join this endeavor," NASA spokesperson Allard Beutel told Xinhua in an email interview.

Beutel's remarks came on the eve of China's planned launch of its Shenzhou IX?manned spacecraft on Saturday to perform the country's first manned space docking mission and send its first female astronaut Liu Yang into space.

Beutel said female astronauts can play an equally important role in space as their male counterparts.

"NASA astronaut corps includes both female and male astronauts who train side-by-side and have identical opportunities to fly and work in space," Beutel said. "In fact, the current head of our astronaut corps is a woman, Dr Peggy Whitson."

Whitson, Beutel said, is a veteran astronaut who holds the American record for the longest duration in space.

"For more than two decades, female astronauts have been an integral part of the NASA human space flight program," Beutel said.