0 Assigned ID: 992 ----- Attempting Submission 1 (Fri Apr 10 22:54:18 GMT 2015) ----- The luminosity function of the Kuiper Belt is a powerful tracer of planetesimal formation and evolution in the outer solar system. Its faint-end behavior has been difficult to determine accurately, due to the paucity of surveys sufficiently sensitive to objects in the relevant luminosity regime. The 194-orbit HST Large Program GO 13633 has nearly tripled the number of known low-inclination Kuiper Belt Objects fainter than H~10; however, this Large Program received no support for calibration, and has not been calibrated sufficiently to use these new KBOs to accurately measure the faint-end behavior of the luminosity function. Here we propose to perform this calibration, and re-analyze the data in order to search for high-inclination KBOs as well. With the proposed calibration and re-analysis, this archival HST data is capable of ruling out a state of collisional equilibrium for small Kuiper Belt objects, a substantial step forward for understanding the history of planetesimal formation and evolution in the outer solar system. SOLAR SYSTEM 0 Regular false false false false false SUPPORTED