FIGURE 2.5.1 Artist’s impression of the debris surrounding Earth. The number of objects in Earth orbit has increased steadily (by 200 per year on average) as more nations develop space programs. NOTE: Size of debris is greatly exaggerated as compared to the size of Earth. SOURCE: Courtesy of the European Space Agency.

FIGURE 2.5.1 Artist’s impression of the debris surrounding Earth. The number of objects in Earth orbit has increased steadily (by 200 per year on average) as more nations develop space programs. NOTE: Size of debris is greatly exaggerated as compared to the size of Earth. SOURCE: Courtesy of the European Space Agency.

programmatic goals. The committee identified three criteria for assessing balance in efforts to address the first four goals.

  1. Capacity to make steady progress. Each major program area needs to be maintained at a level such that the highest-priority intermediate goals can be achieved at a reasonable pace and the next generation of technologies and technical expertise can be developed to sustain long-term progress.

  2. Stability. Rapid downsizing or abrupt redirection of a space activity are disruptive. Reconstituting a lost science or engineering capability or recovering from a major change in program direction can take a long time. A major gap in



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