The presented research aims at refining the "Space Balls" mission concept, which is in its infancy of formulation and aims to obtain high-accuracy estimates of Earth's Energy Imbalance (EEI), the globally and annually integrated net radiative flux at the top-of-the-atmosphere (TOA). The measurement of net radiative flux is facilitated through sensing radiation pressure accelerations acting on a (or multiple) near-spherical low-Earth orbiting spacecraft(s). While an accelerometer at the center of the spacecraft senses the non-gravitational orbit perturbations, the absorbing-reflecting spacecraft skin represents the detector itself, translating the impact of radiation pressure force into sensible accelerations. As with any observing system, this idea faces a multitude of technological and scientific challenges, such as related to the spacecraft characteristics themselves. The shape and thermo-optical properties are crucial for establishing a proportional relationship between impinging photons and the induced acceleration. Another difficulty arises from confounding forces and effects that may impede on radiation pressure acceleration, such as drag. To simulate and assess associated uncertainty, we develop a simulation environment based on Monte, a high-fidelity orbit navigation and mission design software. EEI represents the rate of planetary heat uptake in response to anthropogenic and natural radiative forcings and feedbacks and drives climate change as we see and feel it. Existing radiometers measure the incoming and outgoing radiative fluxes at TOA, but their uncertainties are too large to derive the residual net radiative flux with sufficient accuracy. This direct EEI measurement would be unprecedented and a vital piece in quantifying and better understanding global climate change. The overall feasibility of this approach has been demonstrated in the late 1970's (Cactus accelerometer on Castor satellite), but a dedicated EEI mission does not exist to this day. The capabilities of accelerometers are now at a stage where this measurement might become feasible at the required accuracy and precision. [ABSTRACT FROM AUTHOR]