Preliminary Design of a Space System Operating a Ground-Penetrating Radar

Ground Penetrating Radars are currently used only in ground campaigns or in few airborne installations. A feasibility analysis of a space mission operating a Ground Penetrating Radar is presented in this work. The sensor parametric design, at two selected heights (250 km and 500 km), starts from the user requirements (minimum skin depth of 3 m, 1-m vertical resolution, 10-30 m horizontal resolution). A 500km-altitude, 6am-6pm sun-synchronous orbit is an adequate compromise between atmospheric drag and payload transmitted power (12kW) to achieve a 3-m penetration depth. Thanks to the 6am-6pm orbit selection, the payload average power requirement is kept within feasible limits (1kW) by using NiH2 batteries to supply the radar transmitter and with a strong reduction of the payload duty cycle (40km1100km are observed per orbit). As for the electric power subsystem, a dual-voltage strategy is adopted, with the battery charge regulator supplied at 126V and the bus loads at 50V. The overall average power (1.9kW), accounting for both payload and bus needs, can be supplied by a 20m2 GaAs solar panel for a three-year lifetime. Finally, the satellite mass is kept within reasonable limits (1.6 tons) using inflatable-rigidizable structure for both the payload antenna and solar panel.