In the last decade of the twentieth century U.S. space policy entered an extended period of transition. This was true for several reasons. For one thing, U.S. preeminence in space technology was coming to an end as the European Space Agency developed and made operational its superb Ariane launcher, and the agency's ancillary space capabilities made it increasingly possible for Europe to "go it alone." At the same time, U.S. commitment to sustained leadership in space activities overall waned, and significantly less public monies went into NASA missions. U.S. political commitment to cooperative projects seemingly lessened as well: for example, the United States refrained from developing a probe for the international armada of spacecraft that was launched toward Comet Halley in 1984–1985 and withdrew part of its support from the controversial International Solar Polar Mission to view the Sun from a high altitude, renamed Ulysses and launched in 1990. Of those cooperative projects that remained, NASA increasingly acceded to the demands of international collaborators to develop critical systems and technologies. This overturned the policy of not allowing partners into the critical path—something that had not been accepted in earlier development projects—and was in large measure a pragmatic decision on the part of American officials. Because of the increasing size and complexity of projects, according to Kenneth Pedersen, more recent projects had produced "numerous critical paths whose upkeep costs alone will defeat U.S. efforts to control and supply them." He added, "It seems unrealistic today to believe that other nations possessing advanced technical capabilities and harboring their own economic competitiveness objectives will be amenable to funding and developing only ancillary systems."
In addition to these important developments, in the 1990s the rise of competitive economic activities in space mitigated the prospects for future activities. The brutal competition for launch business, the cutthroat nature of space applications, and the rich possibilities for future space-based economic activities such as asteroid mining were rapidly creating a climate in which international ventures might once again become the exception rather than the rule. John Krige astutely commented in 1997 that "collaboration has worked most smoothly when the science or technology concerned is not of direct strategic (used here to mean commercial or military) importance. As soon as a government feels that its national interests are directly involved in a field of R&D, it would prefer to go it alone." He also noted that the success of cooperative projects may take as their central characteristic that they have "no practical application in at least the short to medium term."
The sole exception to this perspective might be when nations decide that for prestige or diplomatic purposes it is appropriate to cooperate in space. A concern existed that in the United States, where economic competitiveness in space was such a powerful motivation for "going it alone," and where prestige and diplomacy seemed to have taken a backseat to nationalistic hyperbole, that with every passing year there would be less tolerance for large-scale cooperative, and by extension difficult, projects in space. Indeed, there was a constant reduction under way in government spending for space exploration and open discussions of strategies on how to shift the thrust of space flight to the private sector. That would, of necessity, curtail international space exploration activities, with less funding available for scientific space missions, the very missions that are natural candidates for cooperative work. Corporations, that may well provide the greatest share of investment for space flight in the United States in the twenty-first century would be loathe to engage in partnerships in which their technological advantages might be compromised. The proliferation of space technology throughout the world, especially to those nations perceived as rogue states, may well prompt U.S. leaders to clamp down on anything that smacks of technology transfer. (This has already been seen in relation to the supposed satellite technology transferred inadvertently to the People's Republic of China through Hughes Aerospace Corp.) Finally, the disagreeable experiences of such cooperative projects as the International Space Station might sour both national and NASA officials on future endeavors. It is certain, for example, that it will be a long time before anyone in authority in the United States will sign on to an international project of similar complexity.