university observatory support from NSF remained flat; thus, the fraction of research grant funding supported by NSF continued to decrease during the 1990s. In a span of about 15 years, support for the field of astronomy made a major (and largely unplanned) transition from one federal agency to another.
Figure 2.5 details the portion of NASA funding going to various components of the astronomy program. For 1981 to 1985, the data are taken from the 1991 Decadal Report and show the breakdown of astronomy funding into two components: (1) large and medium missions and (2) small programs and grants. For the period beginning in 1986, more detailed and uniform information is available. The large-and medium-mission component is roughly replaced by two components: (1) flight programs and (2) mission operations and data analysis (MO&DA). The small programs and grants component is roughly replaced by two other components: (1) the research and analysis (R&A) program and (2) the suborbital program (primarily support for SOFIA). In both cases, the replacement is approximate, primarily because MO&DA includes support of programs that would fall under the category of small projects and grants in the classification used in the 2000 decadal survey. Note that the increase in MO&DA funding in 1990 is due to the HST program.
Lastly, it is important to point out some real and perceived changes in astronomical research. Three major changes are (1) the increase in international projects both in space (see the NRC report U.S.-European Collaboration in Space Science, National Academy Press, Washington, D.C., 1998) and on the