We propose continue the development of Ultra-high stability space qualified clock and clock synchronization system for science applications, that meets 1E-14 relative frequency stability over short time intervals of 0.1 to 20 seconds. With this year's successful performance demonstration, this development will focus on 1) Finishing performance validation of frequency down converted 100MHz clock performance from cavity locked LISA laser for 1E-14 relative frequency error. 2) Design an engineering clock module capable targeting TRL6 performance. The proposed implementation is

The near-term goal will serve the VLBI Event Horizon science and prove the timing precision and stability needed for PNT. The long-term goal of this effort will be: 1) pursue the space-based optical clock with ground to space time transfer to achieve 1E-18 relative frequency error to enable fundamental physics measurements; 2) enable improved NAV/Comm services required by the exploration and science communities; 3) ensure GSFC stands at the forefront of the ever-improving clock and frequency discipline.