Objective: In response to the EM-1 component of NASA solicitation NNH14ZDA001N: Heliophysics-Technology and Instrument Development for Science (H-TIDS), the Southwest Research Institute (SwRI), NASA/Goddard Space Flight Center (GSFC), and the Jet Propulsion Laboratory propose CuSPP Plus, an enhancement of the already-selected CubeSat mission to study Solar Particles over the Earth's Poles: CuSPP. CuSPP is a 4-year project selected in 2014 (NNH13ZDA001N) to design, develop, and integrate a 3U CubeSat with a novel miniaturized sensor to address the primary science objective: 1) study the sources and acceleration mechanisms of solar and interplanetary (IP) particles near-Earth orbit. CuSPP's technical objective is to increase the technological readiness level (TRL) of our novel in situ Suprathermal Ion Spectrograph (SIS) instrument concept so that it can be proposed and flown with significantly reduced risk and cost on future Heliophysics missions. The enhancement is to add back in the de-scoped Energetic Ion Spectrometer (EIS) instrument that measures ~1-50 MeV/nucleon H—Fe ions. In addition, a magnetometer (MAG) from JPL will be added, because particle intensities within the field-of-views of the two instruments depend upon the magnetic field direction and this cannot be determined a priori outside the Earth's magnetosphere. In addition, CuSPP Plus will need an improved telemetry system in order to handle the much larger Earth-spacecraft distances. The addition of the EIS and MAG instruments and enhanced telemetry will increase the size of CuSPP Plus to 6U, as compared to the 3U CuSPP. Scientific Rationale: Over the past two decades (~1992—2012), simultaneous measurements from NASA's Heliophysics System Observatory (HSO) missions like SoHO, ACE, STEREO, and Wind near 1 AU, and SAMPEX in a Low-Earth Orbit (LEO) have revolutionized our understanding of the origin and acceleration of suprathermal (ST) and energetic particles in the inner heliosphere and their impacts on the near-Earth radiation environment. Despite enormous advances, several questions regarding these energetic particle populations are unanswered, largely because high-cadence, precise measurements of the suprathermal populations are difficult. CuSPP fills this critical gap by measuring the temporal, spectral, and angular distributions of ~3-70 keV/q ST ions that form the seed particles of the energetic particles. CuSPP Plus also measures the energy spectra and composition of the ~1-50 MeV/nucleon H—Fe ions that evolve from the STs and the interplanetary magnetic field that is closely coupled to the particle distributions. This enhancement to the CuSPP mission provides an orbit that is much better suited to heliospheric science and the two additional instruments greatly increase the scientific return from CuSPP.