The satellite-borne instrument is based on a low-cost, modular CubeSat platform. This platform was developed initially by the California Polytechnic State University and has been adopted by several institutions and companies since its debut in 1999. These are included European SMEs that are currently developing off-the-shelf components to be easily combined and integrated into low-cost nano-satellites. Cubesats currently provide an affordable solution for R&D and test-bedding activities at academia and industry. The satellite payload will be a GNSS-R instrument designed and manufactured by UPC, PiCARO, and mostly inherited from past projects. The inclusion of the space-borne receiver in the E-GEM project provides an invaluable contribution towards the development of future space missions based on GNSS-R technology. Also it will obtain an unprecedented extensive testing dataset on which algorithms can be further developed and tested at a moderate cost. This instrument will target the acquisition of land- and cryosphere-reflected signals, in addition to ocean-reflected ones.