The aim of the FlyRadar project (H2020-MSCA-RISE-2020 project of European Commission) is to develop a multimode (GPR and SAR) multi-frequency radar installed on board a UAV dimensioned for Martian exploration and tested on Earth. A GPR is an active remote sensing probe that emits electromagnetic waves and receives the waves reflected by discontinuities that can be the surface of the planet or permittivity contrasts in the interior. Echo analysis provides geometrical and geological information on the surface features to a depth about 100 m that depends on the permittivity of material. Mars is particularly suitable for exploration with such an instrument. The upper crust of Mars is composed of rocks of various origins (volcanic, sedimentary, impact, etc.) clearly visible at the surface of the planet. Mars also presents two permanent polar caps and a range of shallow subsurface buried ice masses in the middle latitude region. The shallow 3D subsurface geometry of these geological features is generally poorly known, but will be accessible using a GPR-SAR instrument. The efficiency of GPR has already been demonstrated on Mars (figure 1). Two orbital radar sounders that work as GPR (MARSIS on Mars Express and SHARAD on MRO) have successfully operated in the last 20 years [1, 2]. These two instruments provided the first images of the subsurface of Mars. The RimFax instrument [3] on board the Perseverance rover is currently in operation to provide high resolution sections of the underground of the Jezero impact crater on Mars. The FlyRadar system will operate several tenth of meters above ground on board a UAV, providing precise and high resolution data, which will be critically needed for example, for future Mars sample return initiatives and human missions. The FlyRadar project is organized around technical, scientific and qualification work packages.