they foster merit-based scientific exploitation of the facilities, while minimizing the cost and administrative overheads that are inherent in a fully shared and managed project. The principle of open skies is compatible with the guiding principle of maximizing future scientific progress. In an increasingly international arena, flexibility will be a key to optimizing the science return from U.S. investments in new facilities.
A prerequisite for a successful partnership is that all parties view the arrangements as being fair and equitable, at least when considered across the sum of shared facilities. For example, under NSF’s open skies policy, access to the U.S. national centimeter-wavelength telescopes (EVLA, GBT, VLBA, and Arecibo), which are the premier facilities in the world at these wavelengths, is allocated without regard to nationality. As a result, overseas investigators make substantial use of those facilities, accounting for typically one-third (for the NRAO telescopes; less for Arecibo) of the allocated observing time. At present, it can be said that U.S. researchers have enjoyed open access to many, though not all, premier international facilities. In addition, private U.S. telescopes do not, as a matter of course, allow open access to the full U.S. community, let alone foreign astronomers. However, the astronomical community does get access to ground-based optical infrared facilities through the Telescope System Instrument Program scheme.
Such imbalances are likely to arise, and when they do, it is incumbent on the agencies and observatory directors to take corrective action. For example, when the fraction of foreign users of a U.S. facility becomes very large, then this can be taken as a sign that the science from that facility is less aligned with U.S. national priorities or that the balance between support of U.S. facilities and the U.S. user community has gotten out of line. Likewise, if a serious asymmetry develops between the United States and foreign facilities, then that is the time to propose reciprocal arrangements that will preserve the principle of open skies. There are two caveats to this approach. For “open skies” and similar arrangements to work, they need to be seen to be symmetrical and fair in terms of scientific opportunity and cost recovery over the long run and averaged over many facilities.
An important goal for the U.S. agencies is to place appropriate value on reciprocity arrangements in providing access to foreign astronomical facilities and data sets for U.S. researchers. To encourage reciprocal arrangements for broad merit-based access to telescopes worldwide, the observing rights and access to survey data, e.g., during validation periods, could be restricted for U.S.-funded facilities to scientists at U.S. institutions, any foreign partners, and other parties with such reciprocity agreements. In any restriction of access to U.S. facilities, care must be taken to address the needs of scientists from countries whose ability to participate in the construction and support of expensive international facilities is limited.