a potential hiatus in U.S. capability to launch RPS-powered spacecraft. Continued inaction will force NASA to make additional, difficult decisions to reduce the science return of some missions and to postpone or eliminate other missions until a source of 238Pu is available.
It has long been recognized that the United States would need to restart domestic production of 238Pu in order to continue producing RPSs. The problem is that the United States has delayed taking action to the point where the situation has become critical, and the dwindling inventory of 238Pu—and uncertainty about the future supply of 238Pu—is now a major constraint on planning the future of the U.S. space program. In recent years, each time a proposal has been made to restore production of 238Pu, action has been deferred. However, the day of reckoning has arrived, and continued delays in taking action to reestablish domestic production of 238Pu will exacerbate the effect of current shortfalls, as detailed in Figure 3.1.
The top part of Figure 3.1 shows three options for future 238Pu supply: (1) funding for 238Pu production is included in