BEIJING, April 2 (Xinhuanet) -- NASA officials and U.S. policymakers are worried America's space program will suffer because of a four-year gap in manned space flight beginning near the end of 2010 when the space shuttle program winds down.

    The next-generation spacecraft, the Orion capsule, won't be ready for manned flight until March 2015 for the next phase of space exploration to the moon and Mars.

    During those four years the United States will have to rely on other nations if it wants to send astronauts and cargo to the international space station.

    "Who knows what the geopolitics is going to be like in 2015?" asks U.S. Sen. Bill Nelson, the Florida Democrat who chairs the Space, Aeronautics and Related Sciences subcommittee. "Is Russia still going to be allied with us? Would they possibly be allied with China at that point?"

    The space agency has been in this position before. There was a six-year gap between the last Apollo flight in 1975 and the first shuttle flight in 1981.

    "It is not a very desirable situation," said John Logsdon, director of the Space Policy Institute at George Washington University. "We will have an orbiting destination that we have spent multiple billions of dollars of U.S. taxpayer money to develop. To not be able to get there except for the good will of others is a little ironic."

    NASA fears the United States will lose its edge as the leading spacefaring nation as Russia, Europe, Japan, China and India improve their ability to send humans and cargo into space. Right now the only three nations with vehicles able to fly people to space are China, Russia and the United States.

    NASA Administrator Michael Griffin recently told lawmakers China's ambitious space program could feasibly beat the United States in the race back to the moon, although he and outside experts say there's no indication yet China is on that path.

    The gap also could contribute to a loss of interest in space exploration by the U.S. public and Congress, and that could diminish the resources allotted to the space agency, said W. Henry Lambright, a political science professor at Syracuse University.

    "It's really important for NASA to have activity, to keep going, to constantly have a face in Washington based on its successes," Lambright said.

    U.S. Sens. Barbara Mikulski, D-Maryland, and Kay Bailey Hutchison, R-Texas, this month proposed increasing NASA's funding by 1 billion dollars. Mikulski also called for a space summit between Congress and the White House to raise the profile of NASA's budget needs.

    Nelson said the space exploration gap could be narrowed to three years if NASA were to get an extra 400 million dollars above the 2008 budget request and an extra 800 million dollars each in 2009 and 2010. NASA's budget request for 2008 is 17.3 billion dollars.

    During the last gap in space flight, which ended in 1981, the agency had a brain drain in which experienced engineers and technicians left for other opportunities and "essentially, the manned space program went off the radar screen," Lambright said.

    "When you don't fly for four or more years, people become stale," Griffin said recently. "Very good people often move into other enterprises where there is more action. Facilities degrade. It's not a good thing."

    (Agencies)