The U.S. ground-based observational solar program led the world for most of the 20th century. This leadership role is now being challenged by the decline in funding in the US, and by other countries that are developing strong observational programs, most notably various European countries and Japan. The existing U.S. telescopes were built for the most part before 1970 and are equipped with focal plane instrumentation that has been upgraded but frequently dates to the 1970s or earlier. Nonetheless, these telescopes are important resources; with more modern focal plane instrumentation, many of the ground-based frontier projects for solar physics in the 1990s could be carried out with existing telescope facilities.
To keep the United States at the forefront of international solar research, the ground-based U.S. solar program for the 1990s must:
focus clearly on the most important scientific problems which can be attacked with available technology, and the technology now under development;
be able to translate the specific plans developed by the community into ongoing projects with some assurance of funding continuity;
provide for a balance between the large-scale, community-based programs and smaller-scale research programs led by individual investigators;
assure a balance between innovative new projects and the fulfillment of commitments to ongoing projects, including those which by their very nature are carried out over long spans of time, based on scientific merit;
assure the training of solar scientists at a level commensurate with the anticipated program beyond the year 2000;
encourage a symbiotic relationship between ground-based and space-based observers, and theoreticians;
provide for the infrastructure needed to support the anticipated program, including an effective capability for reducing and analyzing the extremely large data sets which new generations of solar instruments (and numerical simulations) will provide.
With specific regard to our priorities for the U.S. solar research program in the 1990s, several factors must be kept in mind in addition to the primary constraint, namely that of merit:
the priorities of ground and space-based research are interdependent;
the priorities of the U.S. program depend on international programs and programs of other nations;
the program is motivated by a mixture of long term and short term needs;
the program balances major, moderate, small, and interdisciplinary initiatives;
"major solar initiatives", as defined by the AASC, require multi-year commitments at the NSF division level, not just at the program level;
"moderate solar initiatives", as defined by the AASC, require commitments at the NSF program level, typically for 2-3 years;
"interdisciplinary initiatives", often very large projects, may be of interest to organizational units of NSF other than the usual solar funding sources;
operational systems, such as the U.S. Air Force Solar Observing Optical Network (SOON), must be recognized as programs whose principal responsibilities are to monitor and report solar activity, rather than to support solar physics research. Nevertheless, in the past, solar research has benefited significantly from USAF willingness to provide, for example, SOON Ha images for research purposes (e.g., Solar Maximum Year).
A major scientific goal for ground-based solar research in the 1990s is to understand the physics of solar magnetic fields in the regions of the Sun that are observable from the ground. This is an ambitious and critical goal, and we propose that the major step be taken to reach it by building, together with international partners, a Large Earth-based Solar Telescope -- the LEST.
Research in solar magnetohydrodynamics has the potential to revolutionize our understanding of solar and stellar activity, the outer solar atmosphere, and how the Sun affects Earth. The Sun is the only star