NASA lacks the money to support vigorous science research while building the international space station and returning astronauts to the moon, according to a report released Thursday by the National Research Council.

The end result, the scientists warned, will be further erosion of the nation's leadership in scientific research.

"NASA is being asked to accomplish too much with too little," said the document, prepared by a panel of scientists at the request of Congress.

The proposed 2007 budget for the space agency could weaken programs for space and earth science, jeopardize national research goals and stunt the development of the nation's next generation of scientists, according to the report.

"The cuts fell disproportionately on the small missions and the research and analysis part of the program," said Lennard Fisk, a space science professor at the University of Michigan and former associate NASA administrator who chaired the committee. "These are the foundation programs ... If you disproportionately cut there, you disproportionately cut the pipeline."

The budget constraints will cause many science missions to be delayed or dropped, the report said.

Already, 240 grants affecting 500 postdoctoral fellows, graduate and undergraduate students have been terminated.

"The net result of these actions will be that ... our nation's leadership in Earth and space research and exploration will erode relative to the efforts of other nations," said the report, which was to be presented Thursday at a meeting of a NASA advisory committee in Washington.

NASA spokesman Dwayne Brown said the space agency is in an ongoing discussion with the science community on the budget challenges at meetings this week.

"I think folks are confident that there's going to be a robust and executable science program," said Brown, who hadn't had a chance to read the report. "There has been a very good and open dialogue and discussion."

President Bush's proposed 2007 budget calls for a 3.2 percent increase in NASA spending over last year. Just under a third of the space agency's proposed $16.8 billion budget for 2007 would be devoted to science, but science funding is only expected to grow 1.5 percent next year and 1 percent each year through the end of the decade.

NASA Administrator Michael Griffin said earlier this year that he had to take money from science and exploration programs to make up for an almost $4 billion shortfall over the next four years to pay for finishing the space station and flying the shuttles through 2010.

The report asked the space agency to reverse funding cuts for small missions, research and analysis programs at universities and NASA centers and astrobiology — the study of the origin of life and its existence elsewhere in the cosmos. These areas need an increase of just over 1 percent of NASA's total budget, the report said.

It also asked that money be restored for space station science studying the effects of long duration spaceflight and countermeasures to radiation, saying knowledge in those areas will be needed for missions to the moon and Mars. That funding could also be restored with less than 1 percent of NASA's total budget, the report said.

"These are real programs. They involve real people and real scientists and planning that had taken place for decades," Fisk said.