The TRUTHS satellite carries two main instruments: the Cryogenic Solar Absolute Radiometer (CSAR) and the Hyperspectral Imaging Spectrometer (HIS) as well as a novel onboard calibration system. Together, these instruments will make continuous measurements of both incoming solar radiation and Earth’s reflected radiation. These two observations will be used to evaluate the energy-in to energy-out ratio. The unprecedented quality of these measurements will be the standard reference against which all other imaging satellites can adjust and correct their own observations. The spatial and spectral resolution of the mission will also accelerate our understanding of the causes of change in energy balance and help assess progress stemming from climate action.