The Micro-Sized Microwave Atmospheric Satellite (MicroMAS-2) is a 12-channel passive microwave radiometer on a CubeSat developed by Massachusetts Institute of Technology Lincoln Laboratory. MicroMAS-2 observations (1) enhance the current observing system capabilities and (2) mitigate the potential loss of some existing observations. Observing System Simulation Experiments (OSSEs) quantitatively estimate the expected impact of adding the MicroMAS-2 to the current global operational analysis and forecast systems or to a data gap scenario. First, MicroMAS-2 data on one low Earth-orbiting platform were simulated by the Community Radiative Transfer Model from the NASA GEOS-5 Nature Run, which serves as the truth in the OSSE. The assimilation of the MicroMAS-2 observations into the research version of the January 2015 NOAA Global Data Assimilation System in addition to the current operational observation system and in addition to a data gap scenario shows improvement on both analysis and forecast performance skills.