The Scattered Disc as a Leaking Reservoir: A Lifetime and Source-Rate Budget

This study computes how fast the scattered disc leaks away and how large it must once have been, using published outer Solar System survey values as inputs and a fully deposited calculation. Headline computed quantities include: median_lifetime_Gyr = 0.3; mean_lifetime_Gyr = 0.8; adopted_population_Hlt8 = 20000; loss_rate_per_Gyr = 25000; loss_rate_per_Myr = 25.0. An unfed scattered disc decays almost completely over the age of the Solar System. Either the primordial scattering population was more than a hundred times the present one, or the disc is continuously fed from resonant and classical reservoirs — most likely both. The arithmetic leaves no third option. This study is simulated and computed from stated assumptions and published values; it is not a measurement, and it presents no new observations.