Radar, thermal infrared, and high-energy radiation sensors represent key non-optical approaches to Martian remote sensing, each exploiting different regions of the electromagnetic spectrum to reveal surface and subsurface properties. Radar systems, including synthetic aperture radar and ground-penetrating instruments, actively transmit long-wavelength energy to probe beneath the surface, enabling detection of subsurface ice, layering, and dielectric contrasts despite interference from ionospheric effects and surface clutter. Thermal infrared sensors passively measure emitted radiation to derive temperature, mineralogy, and thermal inertia, providing insight into regolith composition and physical properties to shallow depths influenced by diurnal heating cycles. High-energy radiation sensors (UV, X-ray, gamma ray) characterise atmospheric processes, surface chemistry, and elemental composition, supporting investigations into atmospheric loss, oxidation, and habitability. Together, these complementary sensor types demonstrate the value of multi-spectral integration in advancing understanding of Martian geology, climate evolution, and potential past environments suitable for life.