SESAR (Space Exploration Synthetic Aperture Radar) is a next generation P-band beamforming radar instrument concept that will enable a new class of observations suitable to meet Decadal Survey science goals for planetary exploration. The radar operates at full polarimetry and fine (meter scale) resolution, and achieves beam agility through programmable transmit waveforms and digital beamforming on receive. The radar is based on a low power, lightweight design approach conceived to meet the stringent planetary instrument requirements. This instrument concept has the potential to provide unprecedented surface and nearsubsurface measurements of planetary bodies including the Moon, Mars, and asteroids.