This paper presents an orbit-to-ground model for the atmospheric entry of ChipSats. gram-scale spacecraft that offer unique advantages over their conventionally larger counterparts. ChipSats may prove particularly useful for in-situ measurements in the upper atmosphere. where spatially and temporally varying phenomena are especially difficult to characterize. https://www.roneverhart.com/2-1-2-x-1-4-x-36-Smooth-Saddle-Threshold-NGP-410-36/