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Monitoring the Earth's radiation belt by Low-Earth-Orbit (LEO) satellites has a long history and complemented observations near the high-altitude equatorial plane. However, most of the previous LEO missions suffered from limitations in energy resolution, energy range, L-shell coverage, or the mission lifetime, which leave room for further improvement in this topic. Here we present multi-year (January 2019~February 2021) observations of energetic (0.03 MeV~1.8 MeV) electrons by the Korean NextSat-1 (altitude~575 km) with high energy resolution (0.006-0.4 MeV) and seamless L-shell coverage. For <80 keV electrons, the slot-region outer edge moves inward with increasing geomagnetic activity, which agrees with previous Van Allen Probes reports. The behavior is more conspicuous for lower-energy electrons. Latitudinal profiles of outer-belt electron flux are smoother equatorward of the geosynchronous footprint latitudes (|MLAT|~66 o ) than poleward. The NextSat-1 electron flux is positively correlated to geosynchronous observations, with the coefficient generally higher for higher electron energies. Also, both the geosynchronous and NextSat-1 data exhibit similar spectral indices close to -3 in the log-log space. All these results complement and expand previous knowledge on energetic electrons. The main findings are discussed in the context of existing literature.

&lt;p&gt;Dielectric constant describes the electrical properties of a material and is related to soil moisture. The latter is known as a critical parameter in hydrological and climate science; however, computing such dielectric constants is a challenging problem as many factors effect the constant values, e.g., soil type, texture and temperature. Global Navigation Satellite System-Reflectometry (GNSS-R) is a relatively new remote sensing technique being used to infer geophysical information by measuring not only the signals coming directly from the GNSS satellites, but also the reflected GNSS signals from the Earth&amp;#8217;s surface. This research presents a new, straightforward approach for computing relative dielectric constant by means of reflectivity, which is the ratio between the signal-to-noise ratio (SNR) of direct waves and SNR of reflected waves. With the well-known relationship between the reflectivity, Fresnel coefficient, and surface roughness, the dielectric constant can be expressed as the combination of horizontal and vertical Fresnel coefficients. Dual, circular-polarized antennas in the zenith and nadir directions were used to capture electromagnetic waves emitted from GNSS satellites and transform them into electrical signals. The zenith direction antenna senses the direct signals which have right-hand circular polarization, and the nadir direction antenna senses right and left-hand circular polarization of reflected GNSS signals created by electromagnetic reflections on the surfaces. An in-house Software Defined Radio (SDR) receiver, coupled with a commercial radio frequency frontend were used to collect, store and analyze both direct and reflected signals. Data collection experiments were carried in areas of smooth surface, and the observed SNR values were applied to the method of quantitative dielectric constant. The computation results demonstrate that derived dielectric constants have the values around 10 and are independent on the incident angle of waves coming to the specular point. Applying the additional data processing to the results, it is relevant to the dielectric constant measured by Time Domain Reflectometry techniques used commercial soil moisture probes at the same time. There have been few attempts to establish the dielectric constant model using forward scattered electromagnetic signals, especially GNSS signals. The proposed calculation method is able to solve the difficulties in analyzing with respect to the incident angle, as well as the polarization. Therefore, it is expected that the inversion approach of the retrieval algorithm makes the GNSS-R applicable to not only the scientific but also the industrial applications. In the future, the dielectric constant will be enhanced to include roughness information of the Earth&amp;#8217;s surface and to attempt to calibrate surface soil moisture measurements for various soil types.&lt;/p&gt;