The survey committee recommends the following augmentation priorities to aid in implementing a program under a more favorable budgetary environment:
Augmentation Priority 1. If even modest additional financial resources can be made available early in the decade, the implementation of the DRIVE initiative should be accelerated.
Augmentation Priority 2. Given sufficient funds throughout the decade, the Explorer line should be further augmented so as to increase the cadence and amount of funding available for missions including Missions of Opportunity.
Augmentation Priority 3. Given further budget augmentation, the cadence of STP missions should increase to allow the recommended third-priority mid-size science target (MEDICI) to be initiated in this decade.
Augmentation Priority 4. The major-mission-line recommendation (GDC) should be implemented in the most cost-effective manner, if possible with a funding bump as shown in Figure 6.1.
Collaborations between NASA and foreign space agencies have historically achieved major science at a relatively low cost to the United States. Missions labeled with an asterisk in Figure 6.2 are examples of such international collaborations. These include SOHO, Ulysses, Yohkoh, CLUSTER, Hinode, and Solar Orbiter. Collaborations with the Japanese space agency have been particularly fruitful, with investments of Explorer-size funds having resulted in full U.S. participation in major missions (Yohkoh, Hinode). Such missions leverage U.S. investments while simultaneously sustaining a U.S. leadership role in science.3
Opportunities continue to arise for NASA to collaborate with other nations, and in so doing to obtain a high science return at a relatively low cost. The Solar-C mission, a follow-on to Yohkoh and Hinode that will study the magnetic coupling of the lower solar atmosphere and the corona, has been confirmed by Japan and would greatly benefit from contributions of instrumentation from the United States. A mission concept has also been developed in Japan, Canada, and Europe that involves a fleet of spacecraft performing simultaneous in situ measurements of fields and plasmas at key locations in the magnetosphere. Finally, NASA support for the U.S.-Taiwanese FORMOSAT-3/COSMIC microsatellite science mission for weather, climate, space weather, and geodetic research illustrates the range of possible collaborative opportunities that might arise. The augmented Explorer line is the recommended source of funding for participation in most such international collaborations.
3 At the same time, collaborations with international partners add complexity and risk that must be actively managed. See, for example, National Research Council, U.S.-European Collaboration in Space Science, National Academy Press, Washington, D.C., 1998.