In situ planetary instruments face challenges that greatly exceed even the challenges of developing in-space Earth-orbiting instruments. Because of restricted payload masses for these ambitious missions, planetary in situ instruments must be very small (a few kg, at most), consume low power (20W or less), take up low volume (a few liters, at most), and be highly automated from instrument turn-on to data transmission. To address this need, a compact improvement on time-resolved streak-tube and intensified photodiode (IPD) technology will be developed that is better at achieving the sensitivity, resolution, and count rates. The proposed hybrid intensified solid-state pixelated anode detector (ISPAD) senses and timestamps microchannel-plate (MCP) -multiplied electron clouds at picosecond time scales, allowing photon detection with subpixel spatial resolution, at rates ranging from a few counts per second to billions of counts per second. In Phase I, a solid-state multi-anode readout circuit, optimized for operation in an MCP image tube, will be designed and simulated. After updating the engineering requirements control document, a complete layout, extraction, and simulation of the pixel elements will be performed. A vacuum header will be designed, and the process of integrating the tube body with the photocathode will be established. A preliminary design review (PDR) with NASA technical monitors, instrument designers, scientists, and other stakeholders will then be conducted.