From RainCube to INCUS: Using Miniaturized Microwave Instruments to Analyze the Dynamics of Tropical Convection

This narrative tells the story of how NASA's INCUS (INvestigation of Convective UpdraftS) mission was conceived and designed, to identify and flesh out a scientific investigation that would be conducted using newly developed miniaturized weather radars and radiometers. Different considerations led to the conception of a new observation strategy, consisting of deploying identical replicas of the latest-technology instruments in a tight convoy in low Earth orbit. The scientific goal of this concept is to observe systematically and globally the main thermo-dynamical process in convective storms: the vertical transport of air and moisture from the surface up to the upper troposphere. How the different elements of the concept were fleshed out is recounted with specific attention to the top-level requirements placed on the microwave instruments and to their scientific justification. One of the main “morals” of the story is to highlight the need to pay close attention to the sufficiency of top-level requirements in addition to their necessity, and not to hesitate to add explicit requirements when expanding the capabilities of a heritage instrument in order to ensure that the top-level requirements are indeed sufficient as well as necessary.