Thank you for engaging with our analysis, @NASAAdmin Isaacman. As we stated in the report, this is an exercise worth pursuing. We share your desire to make sure that every decision and every dollar spent creates more wins for science. We agree plutonium shouldn't sit idle. That's why we keep arguing for more resources for NASA science to pursue high-priority missions to the outer solar system. But even if PROMISE comes in below our estimates, there are real opportunity costs in the use of NASA's spare MMRTG and its limited supply of plutonium-238. Using 4.8 kg now is equivalent to nearly 20 years of natural decay losses across NASA's supply. We want to make sure the scientific outcomes justify this cost, should NASA decide to pursue this effort. That's why we recommended incorporating the science goals of Endurance-A: sample collection across the South Pole–Aitken basin by a rover capable of long-distance drives. The science was recommended by the decadal survey and reaffirmed just this week by NASA's own SPARX Science Definition Team. PROMISE may be promising for that task. We look forward to the ongoing conversation about keeping the United States on the cutting edge of scientific discovery.